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sx1239 www.semtech.com page 1 advanced communica tions & sensing datasheet sx1239 receiver low power integrated uhf receiver rev 3 - jan 2011 the sx1239 is a highly integrated rf receiver capable of operation over a wide frequency range, including the 433, 868 and 915 mhz license-free ism (industry scientific and medical) frequency bands. its hi ghly integrated architecture allows for a minimum of external components whilst maintaining maximum design flexibility. all major rf communication parameters are programmable and most of them can be dynamically set. the sx1239 offers the unique advantage of programmable narrow-band and wide-band communication modes without the need to modify external components. the sx1239 is optimized for low power consumption while offering high sensitivity and channelized operation. truerf? technology enables a lowcost external component count (elimination of the saw filter) whilst still satisfying etsi and fcc regulations. ? automated meter reading ? wireless sensor networks ? home and building automation ? wireless alarm and security systems ? industrial monitoring and control ? europe: en 300-220-1 ? north america: fcc part 15.247, 15.249, 15.231 ? narrow korean and japanese bands ? high sensitivity: down to -120 dbm at 1.2 kbps ? high selectivity: 16-tap fir channel filter ? bullet-proof front end: iip3 = -18 dbm, iip2 = +35 dbm, 80 db blocking immunity, no image frequency response ? low current: rx = 16 ma, 100na register retention ? constant rf performance over voltage range of chip ? fsk bit rates up to 300 kb/s ? fully integrated synthesizer with a resolution of 61 hz ? fsk, gfsk, msk, gm sk and ook demodulation ? built-in bit synchronizer performing clock recovery ? incoming sync word recognition ? 115 db+ dynamic range rssi ? automatic rf sense with ultra-fast afc ? packet engine with crc, aes- 128 encrypti on and 66- byte fifo ? built-in temperature sensor and low battery indicator ? qfn 24 package - operating range [-40;+85c] ? pb-free, halogen free, ro hs/weee compliant product general description applications markets key product features ordering information part number delivery moq / multiple sx1239imltrt tape & reel 3000 pieces lna single to differential mixers / modulators decimation and & filtering demodulator & bit synchronizer packet engine & 66 bytes fifo control registers - shift registers - spi interface spi dio0 rssi afc division by 2, 4 or 6 frac-n pll synthesizer xo 32 mhz xtal tank inductor loop filter rfin nc reset power distribution system vbat1&2 vr_ana vr_dig nc rc oscillator gnd gnd nc dio1 dio2 dio3 dio4 dio5
www.semtech.com page 2 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 table of contents page 1. general description ........................................................................................................ ........................................ 8 1.1. simplified block diagram ................................................................................................. ............................... 8 1.2. pin and marking diagram.................................................................................................. .............................. 9 1.3. pin description .......................................................................................................... .................................... 10 2. electrical characteristics....................... .......................................................................... ...................................... 11 2.1. esd notice............................................................................................................... ..................................... 11 2.2. absolute maximum rating s ................................................................................................. ......................... 11 2.3. operating range.......................................................................................................... ................................. 11 2.4. chip specification ....................................................................................................... .................................. 12 2.4.1. power consumption ...................................................................................................... ........................... 12 2.4.2. frequency synthesis .................................................................................................... ............................ 12 2.4.3. receiver ............................................................................................................... .................................... 13 2.4.4. digital specification .................................................................................................. ................................ 14 3. chip description........................................................................................................... ......................................... 15 3.1. power supply strategy.................................................................................................... .............................. 15 3.2. low battery detector..................................................................................................... ................................ 15 3.3. frequency synthesis...................................................................................................... ............................... 15 3.3.1. reference oscillator ................................................................................................... .............................. 15 3.3.2. clkout output ......................................................................................................... ...............................16 3.3.3. pll architecture ....................................................................................................... ................................ 16 3.3.4. lock time ............................................................................................................. .....................................17 3.3.5. lock detect indicator.................................................................................................. .............................. 17 3.4. receiver description ..................................................................................................... ................................ 17 3.4.1. block diagram .......................................................................................................... ................................ 17 3.4.2. lna - single to differe ntial buffer ................................................................................... ..........................18 3.4.3. automatic gain control ................................................................................................. ........................... 18 3.4.4. continuous-time dagc................................................................................................... ........................ 20 3.4.5. quadrature mixer - adcs - decimators................................................................................... ................. 20 3.4.6. channel filter ......................................................................................................... .................................. 20 3.4.7. dc cancellation ........................................................................................................ ............................... 21 3.4.8. complex filter - ook ................................................................................................... ............................ 22 3.4.9. rssi ................................................................................................................... ...................................... 22 3.4.10. cordic ................................................................................................................ ..................................... 22 3.4.11. bit rate setting ...................................................................................................... ................................ 22 3.4.12. fsk demodulator ....................................................................................................... ............................ 23 3.4.13. ook demodulator ...................................................................................................... .............................24 3.4.14. bit synchronizer ..................................................................................................... .................................26 3.4.15. frequency error indicator.................... ......................................................................... .......................... 26 3.4.16. automatic frequency correction ............ ............................................................................ .................... 27 3.4.17. optimized setup for low mo dulation index systems ...................................................................... ....... 28
www.semtech.com page 3 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 3.4.18. temperature sensor ... ................................................................................................ ............................29 3.4.19. timeout function...................................................................................................... .............................. 29 4. operating modes ............................................................................................................ ...................................... 30 4.1. basic modes.............................................................................................................. .................................... 30 4.2. automatic se quencer and wake-up times ..................... ............................................................... .............. 30 4.2.1. receiver startup time.................................................................................................. ............................ 30 4.2.2. rx start procedure ..................................................................................................... .............................. 32 4.2.3. optimized frequency hopping sequences .... .............................................................................. ............ 32 4.3. listen mode ............................................................................................................. ...................................... 33 4.3.1. timings ................................................................................................................ ..................................... 33 4.3.2. criteria ............................................................................................................... ....................................... 34 4.3.3. end of cycle actions ................................................................................................... ............................. 34 4.3.4. rc timer accuracy ...................................................................................................... ............................ 35 4.4. automodes ............................................................................................................... ..................................... 36 5. data processing............................................................................................................ ........................................ 37 5.1. overview ................................................................................................................. ...................................... 37 5.1.1. block diagram .......................................................................................................... ................................ 37 5.1.2. data operation modes ................................................................................................... .......................... 37 5.2. control block description ................................................................................................ .............................. 38 5.2.1. spi interface.......................................................................................................... ................................... 38 5.2.2. fifo ................................................................................................................... ...................................... 39 5.2.3. sync word recognition .................................................................................................. .......................... 40 5.2.4. packet handler ......................................................................................................... ................................ 41 5.2.5. control ................................................................................................................ ...................................... 41 5.3. digital io pins mapping ...................... ........................................................................... ................................ 42 5.3.1. dio pins mapping in continuous mode ...... .............................................................................. ............... 42 5.3.2. dio pins mapping in packet mode ........................................................................................ .................. 42 5.4. continuous mode ......................................................................................................... ................................. 43 5.4.1. general description.................................................................................................... .............................. 43 5.4.2. rx processing .......................................................................................................... ................................ 43 5.5. packet mode .............................................................................................................. ................................... 44 5.5.1. general description.................................................................................................... .............................. 44 5.5.2. packet format .......................................................................................................... ................................ 44 5.5.3. processing (without aes)............... ................ ................ ................. ................ ............... .......................... 47 5.5.4. aes .................................................................................................................... ...................................... 47 5.5.5. handling large packets ................................................................................................. .......................... 48 5.5.6. packet filtering....................................................................................................... .................................. 48 5.5.7. dc-free data mechanis ms ................................................................................................ ...................... 50 6. configuration and status registers ......................................................................................... ............................. 52 6.1. general description ...................................................................................................... ................................ 52 6.2. common configuration registers ........................................................................................... ...................... 55 6.3. receiver registers ...................................................................................................... .................................. 58
www.semtech.com page 4 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 6.4. irq and pin mapping registers ........................................................................................... ......................... 60 6.5. packet engine registers.................................................................................................. ............................. 62 6.6. temperature sensor regi sters ............................................................................................. ........................ 65 6.7. test registers ........................................................................................................... .................................... 65 7. application information ............................ ........................................................................ ..................................... 66 7.1. crystal resonator specification .......................................................................................... .......................... 66 7.2. reset of the chip ........................................................................................................ .................................. 66 7.2.1. por.................................................................................................................... ...................................... 66 7.2.2. manual reset .......................................................................................................... ..................................67 7.3. reference design .................................. ....................................................................... ................................ 67 8. packaging information ...... ................................................................................................ .................................... 68 8.1. package outline drawing....................... ........................................................................... ............................ 68 8.2. recommended land patter n ................................................................................................. ....................... 68 8.3. thermal impedance ....................................................................................................... ............................... 69 8.4. tape & reel specification................................................................................................ ............................. 69 9. chip revisions ............................................................................................................. ......................................... 70 9.1. rc oscillator calibration................................................................................................ ............................... 70 9.2. listen mode.............................................................................................................. ..................................... 70 9.2.1. resolutions............................................................................................................ ................................... 70 9.2.2. exiting listen mode .................................................................................................... .............................. 71 9.3. ook floor threshold default setting ........... ........................................................................... ..................... 71 9.4. afc control .............................................................................................................. .................................... 71 9.4.1. afcautoclearon ......................................................................................................... .............................. 71 9.4.2. afclowbetaon and lowbetaafcoffset...................................................................................... ............... 71 9.5. continuousdagc........................................................................................................... ................................. 71 10. revision history .......................................................................................................... .......................................... 72
www.semtech.com page 5 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 index of figures page figure 1. block diagram ..................................................................................................... ........................................... 8 figure 2. pin diagram ....................................................................................................... ............................................. 9 figure 3. marking diagram ................................................................................................... ......................................... 9 figure 4. tcxo connection ................................................................................................... ..................................... 15 figure 5. receiver block diagr am ............................................................................................ ................................... 17 figure 6. agc thresholds settings ........................................................................................... .................................. 19 figure 7. cordic extraction ................................................................................................. ......................................... 22 figure 8. ook peak demodulator description .................................................................................. .......................... 24 figure 9. floor threshold optimization ......... ............................................................................. ................................. 25 figure 10. bit synchronizer description ..................................................................................... ................................. 26 figure 11. fei process ...................................................................................................... .......................................... 27 figure 12. optimized afc (afclowbetaon=1) ................................................................................... ........................... 28 figure 13. temperature sensor response ...................................................................................... ........................... 29 figure 14. rx startup - no agc, no afc ...................................................................................... .............................. 31 figure 15. rx startup - agc, no afc ......................................................................................... ................................ 31 figure 16. rx startup - agc and afc ......................................................................................... ............................... 31 figure 17. listen mode sequence (no wanted signal is received) .............................................................. ................ 33 figure 18. listen mode sequence (wanted signal is received) ................................................................. .................. 35 figure 19. auto modes of packet handler ........ ............................................................................. .............................. 36 figure 20. sx1239 data processing conceptual vi ew ........................................................................... .................... 37 figure 21. spi timing diagram (single access) ............................................................................... ........................... 38 figure 22. fifo and shift register (sr) ..................................................................................... ................................ 39 figure 23. fifolevel irq source behavior .... ................................................................................ .............................. 40 figure 24. sync word recognition ............................................................................................ .................................. 41 figure 25. continuous mode conceptual view .................................................................................. ......................... 43 figure 26. rx processing in continuous mode ................................................................................. .......................... 43 figure 27. packet mode conceptual view ...................................................................................... ............................. 44 figure 28. fixed length packet format ....................................................................................... ............................... 45 figure 29. variable length packet format .................................................................................... .............................. 46 figure 30. unlimited length packet format ................................................................................... ............................. 46 figure 31. crc implementation ....................... ........................................................................ ................................... 50 figure 32. manchester decoding ..................... ......................................................................... .................................. 50 figure 33. data de-whitening ................................................................................................ ..................................... 51 figure 34. por timing diagram ............................................................................................... .................................. 66 figure 35. manual reset timing diagram ........ .............................................................................. ............................. 67 figure 36. application schematic ............................................................................................ .................................... 67 figure 37. package outline drawing .......................................................................................... ................................. 68 figure 38. recommended land pattern ......................................................................................... ............................ 68 figure 39. tape & reel specification ........................................................................................ .................................. 69 figure 40. listen mode resolutions, v2a .................................................................................... ............................... 70 figure 41. listen mode resolution, v2b .......... ............................................................................ ............................... 71
www.semtech.com page 6 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 figure 42. exiting listen mode in sx1239 v2a ................................................................................ ........................... 71 figure 43. regtestook description ........................................................................................... ................................. 71 index of tables page table 1. sx1239 pinouts ...................................................................................................... ........................................ 10 table 2. absolute maximum ratings ................. ........................................................................... ................................ 11 table 3. operating range ..................................................................................................... ....................................... 11 table 4. power consumption specification ....... .............................................................................. ............................. 12 table 5. frequency synthesizer specification ................................................................................. ............................. 12 table 6. receiver specification .............................................................................................. ...................................... 13 table 7. digital specification ............................................................................................... ......................................... 14 table 8. lna gain settings ................................................................................................... ....................................... 18 table 9. receiver performance summary ........................................................................................ ............................ 19 table 10. available rxbw settings ............................................................................................ ................................... 21 table 11. bit rate examples .................................................................................................. ...................................... 23 table 12. basic receiver modes ............................................................................................... ................................... 30 table 13. range of durations in listen mode ... ............................................................................... ............................ 33 table 14. signal acceptance criteria in listen mode .......................................................................... ......................... 34 table 15. end of listen cycle actions ........................................................................................ .................................. 34 table 16. status of fifo when switching between diffe rent modes of the chip .................................................. ....... 40 table 17. dio mapping, continuous mode ....................................................................................... ........................... 42 table 18. dio mapping, packet mode ........................................................................................... .............................. 42 table 19. registers summary .................................................................................................. .................................... 52 table 20. common configuration registers ......... ............................................................................ ............................ 55 table 21. receiver registers ................................................................................................. ...................................... 58 table 22. irq and pin mapping registers ........ .............................................................................. ............................. 60 table 23. packet engine registers ............................................................................................ .................................. 62 table 24. temperature sensor registers ....................................................................................... .............................. 65 table 25. test registers ..................................................................................................... ......................................... 65 table 26. crystal specification .............................................................................................. ....................................... 66 table 27. chip identification ................................................................................................ ......................................... 70 table 28. revision history ................................................................................................... ......................................... 72
www.semtech.com page 7 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 acronyms bom bill of materials lsb least significant bit br bit rate msb most significant bit bw bandwidth nrz non return to zero ccitt comit consultatif international tlphonique et tlgraphique - itu ook on off keying crc cyclic redundancy check pa power amplifier dac digital to analog converter pcb printed circuit board etsi european telecommunications standards institute pll phase-locked loop fcc federal communications commission por power on reset fdev frequency deviation rbw resolution bandwidth fifo first in first out rf radio frequency fir finite impulse response rssi received signal strength indicator fs frequency synthesizer rx receiver fsk frequency shift keying saw surface acoustic wave gui graphical user interface spi serial peripheral interface ic integrated circuit sr shift register id identificator stby standby if intermediate frequency tx transmitter irq interrupt request uc microcontroller itu international telecommunication union vco voltage controlled oscillator lfsr linear feedback shift register xo crystal oscillator lna low noise amplifier xor exclusive or lo local oscillator
www.semtech.com page 8 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 this product datasheet contains a detailed description of th e sx1239 performance and functionality. please consult the semtech website for the la test updates or errata. refer to section 9 of this docume nt to identify chip revisions. 1. general description the sx1239 is a single-chip integrated circuit ideally suited for today's high pe rformance ism band rf applications. the sx1239's advanced features set, including state of the art packet engine greatl y simplifies system design whilst the high level of integration reduces the external bom to a handful of passive decoupling and matching components. it is intended for use as high-performance, low-cost fsk and ook rf rece iver for robust frequency ag ile rf links, and where stable and constant rf performance is required over the full operating range of the device down to 1.8v. the sx1239 is intended for applications over a wide frequen cy range, including the 433 mhz and 868 mhz european and the 902-928 mhz north american ism bands. coupled with a very aggressive sensitivity, th e advanced system features of the sx1239 include a 66 byte rx fifo, configurable auto matic packet handler, listen mode, temperature sensor and configurable dios which gr eatly enhance system flexibility whilst at the same time significantly reducing mcu requirements. the sx1239 complies with both etsi and fcc regulatory requirements and is available in a 5 x 5 mm qfn 24 lead package 1.1. simplified block diagram figure 1. block diagram lna single to differential mixers / modulators decimation and & filtering demodulator & bit synchronizer packet engine & 66 bytes fifo control registers - shift registers - spi interface rssi afc division by 2, 4 or 6 frac-n pll synthesizer xo 32 mhz xtal tank inductor loop filter rfin reset nc power distribution system vbat1&2 vr_ana vr_dig rc oscillator frequency synthesis receiver blocks control blocks primarily analog primarily digital gnd spi dio0 gnd dio1 dio2 dio3 dio4 dio5 nc nc
www.semtech.com page 9 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 1.2. pin and marking diagram the following diagram shows the pin arrangement of the qfn package, top view. figure 2. pin diagram figure 3. marking diagram notes yyww refers to the date code xxxxxx refers to the lot number c b
www.semtech.com page 10 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 1.3. pin description table 1 sx1239 pinouts number name type description 0 ground - exposed ground pad 1 vbat1 - supply voltage 2vr_ana - regulated supply voltage for analogue circuitry 3 vr_dig - regulated supply voltage for digital blocks 4xta i/o xtal connection 5xtb i/o xtal connection 6 reset i/o reset trigger input 7dio0 i/o digital i/o, software configured 8 dio1/dclk o digital output, software configured 9dio2/data o digital output, software configured 10 dio3 i/o digital i/o, software configured 11 dio4 i/o digital i/o, software configured 12 dio5 i/o digital i/o, software configured 13 vbat2 - supply voltage 14 gnd - ground 15 sck i spi clock input 16 miso o spi data output 17 mosi i spi data input 18 nss i spi chip select input 19 nc - do not connect 20 gnd - ground 21 rfin i rf input 22 gnd - ground 23 nc - do not connect 24 nc - do not connect
www.semtech.com page 11 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 2. electrical characteristics 2.1. esd notice the sx1239 is a high performance radio frequency device. ? class 2 of the jedec standard jesd22-a114-b (human body model) on all pins. ? class b of the jedec standard jesd22-a115-a (machine model) on all pins. class iv of the jedec standard jesd22-c101c (charged device model) on pins 2-3-21-23-24, class iii on all other pins. it should thus be handled with all the necessary esd precautions to avoid any permanent damage. 2.2. absolute maximum ratings stresses above the values listed below may cause permanent device failure. exposure to absolute maximum ratings for extended periods may af fect device reliability. table 2 absolute maximum ratings 2.3. operating range table 3 operating range symbol description min max unit vddmr supply voltage -0.5 3.9 v tmr temperature -55 +115 c tj junction temperature - +125 c pmr rf input level - +6 dbm symbol description min max unit vddop supply voltage 1.8 3.6 v top operational temperature range -40 +85 c clop load capacitance on digital ports - 25 pf ml rf input level - 0 dbm
www.semtech.com page 12 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 2.4. chip specification the tables below give the electrical specifications of th e receiver under the following conditions: supply voltage vbat1= vbat2=vdd=3.3 v, temperature = 25 c, fxosc = 32 mhz, f rf = 915 mhz, 2-level fsk modulation without pre-filtering, bit rate = 4.8 kb/s and terminated in a matche d 50 ohm impedance, unl ess otherwise specified. note unless otherwise specified, the performances in the other frequency bands are similar or better. 2.4.1. power consumption table 4 power consumption specification 2.4.2. frequency synthesis table 5 frequency synthesizer specification symbol description conditions min typ max unit iddsl supply current in sleep mode - 0.1 1 ua iddidle supply current in idle mode rc oscillator enabled - 1.2 - ua iddst supply current in standby mode crystal oscillator enabled - 1.25 1.5 ma iddfs supply current in synthesizer mode -9-ma iddr supply current in receive mode - 16 - ma symbol description conditions min typ max unit fr synthesizer frequency range programmable 290 424 862 - - - 340 510 1020 mhz mhz mhz fxosc crystal oscillator frequency see section 7.1 - 32 - mhz ts_osc crystal oscillator wake-up time - 250 500 us ts_fs frequency synthesizer wake-up time to plllock signal from standby mode - 80 150 us ts_hop frequency synthesizer hop time at most 10 khz away from the target 200 khz step 1 mhz step 5 mhz step 7 mhz step 12 mhz step 20 mhz step 25 mhz step - - - - - - - 20 20 50 50 80 80 80 - - - - - - - us us us us us us us fstep frequency synthesizer step fstep = fxosc/2 19 -61.0 - hz frc rc oscillator frequency after calibration - 62.5 - khz brf bit rate, fsk programmable 1.2 - 300 kbps bro bit rate, ook programmable 1.2 - 32.768 kbps
www.semtech.com page 13 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 2.4.3. receiver all receiver tests are performed with rxbw = 10 khz (single side bandwidth) as programmed in regrxbw , receiving a pn15 sequence with a ber of 0.1% (bit synchronizer is e nabled), unless otherwise specified. the lna impedance is set to 200 ohms, by setting bit lnazin in reglna to 1. blocking tests are performed with an unmodulated interferer. the wanted signal power for the blocking immunity, acr, iip2, iip 3 and amr tests is set 3 db above the nominal sensitivity level. table 6 receiver specification symbol description conditions min typ max unit rfs_f fsk sensitivity, highest lna gain fda = 5 khz, br = 1.2 kb/s fda = 5 khz, br = 4.8 kb/s fda = 40 khz, br = 38.4 kb/s - - - -118 -114 -105 - - - dbm dbm dbm fda = 5 khz, br = 1.2 kb/s* --120-dbm rfs_o ook sensitivity, highest lna gain br = 4.8 kb/s - -112 -109 dbm ccr co-channel rejection -13 -10 - db acr adjacent channel rejection offset = +/- 25 khz offset = +/- 50 khz - 37 42 42 - - db db bi blocking immunity offset = +/- 1 mhz offset = +/- 2 mhz offset = +/- 10 mhz - - - -45 -40 -32 - - - dbm dbm dbm blocking immunity wanted signal at sensitivity +16db offset = +/- 1 mhz offset = +/- 2 mhz offset = +/- 10 mhz - - - -36 -33 -25 - - - dbm dbm dbm amr am rejection , am modulated interferer with 100% modulation depth, fm = 1 khz, square offset = +/- 1 mhz offset = +/- 2 mhz offset = +/- 10 mhz - - - -45 -40 -32 - - - dbm dbm dbm iip2 2nd order input intercept point unwanted tones are 20 mhz above the lo lowest lna gain highest lna gain - - +75 +35 - - dbm dbm iip3 3rd order input intercept point unwanted tones are 1mhz and 1.995 mhz above the lo lowest lna gain highest lna gain - -23 +20 -18 - - dbm dbm bw_ssb single side channel filter bw programmable 2.6 - 500 khz imr_ook image rejection in ook mode wanted signal level = -106 dbm 27 30 - db ts_re receiver wake-up time, from pll locked state to rxready rxbw = 10 khz, br = 4.8 kb/s rxbw = 200 khz, br = 100 kb/s - - 1.7 96 - - ms us ts_re_agc receiver wake-up time, from pll locked state, agc enabled rxbw = 10 khz, br = 4.8 kb/s rxbw = 200 khz, br = 100 kb/s -3.0 163 ms us ts_re_agc &afc receiver wake-up time, from pll lock state, agc and afc enabled rxbw = 10 khz, br = 4.8 kb/s rxbw = 200 khz, br = 100 kb/s 4.8 265 ms us
www.semtech.com page 14 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 * set sensitivityboost in regtestlna to 0x2d to reduce the noise floor in the receiver 2.4.4. digital specification conditions: temp = 25c, vdd = 3.3v, fxosc = 32 mhz, unless otherwise specified. table 7 digital specification ts_fei fei sampling time receiver is ready - 4.t bit -- ts_afc afc response time receiver is ready - 4.t bit -- ts_rssi rssi response time receiver is ready - 2.t bit -- dr_rssi rssi dynamic range agc enabled min max - - -115 0 - - dbm dbm symbol description conditions min typ max unit v ih digital input level high 0.8 - - vdd v il digital input level low - - 0.2 vdd v oh digital output level high imax = 1 ma 0.9 - - vdd v ol digital output level low imax = -1 ma - - 0.1 vdd f sck sck frequency - - 10 mhz t ch sck high time 50 - - ns t cl sck low time 50 - - ns t rise sck rise time - 5 - ns t fall sck fall time - 5 - ns t setup mosi setup time from mosi change to sck rising edge 30 - - ns t hold mosi hold time from sck rising edge to mosi change 60 - - ns t nsetup nss setup time from nss fa lling edge to sck rising edge 30 - - ns t nhold nss hold time from sck falling edge to nss rising edge, normal mode 30 - - ns t nhigh nss high time between spi accesses 20 - - ns t_data data hold and setup time 250 - - ns
www.semtech.com page 15 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 3. chip description this section describes in depth the architecture of the sx1239 low-power, highly integrated receiver. 3.1. power supply strategy the sx1239 employs an advanced power supply scheme, whic h provides stable operating characteristics over the full temperature and voltage range of operation. the sx1239 can be powered from any low-noise voltage source via pins vbat1 and vbat2. decoupling capacitors should be connected, as suggested in the reference design on vr_d ig and vr_ana pins to ensure a correct operation of the built-in voltage regulators. 3.2. low battery detector a low battery detector is also included allowing the ge neration of an interrupt signal in response to passing a programmable threshold adjust able through the register reglowbat . the interrupt signal can be mapped to any of the dio pins, through the programmation of regdiomapping . 3.3. frequency synthesis the lo generation on the sx1239 is based on a state-of-the-art fractional-n pll. the pll is fully integrated with automatic calibration. 3.3.1. reference oscillator the crystal oscillator is the main timing reference of the sx1239 . it is used as a reference for the frequency synthesizer and as a clock for the digital processing. the xo startup time, ts_osc, depends on the actual xtal be ing connected on pins xta and xtb. when using the built- in sequencer, the sx1239 optimizes the startup time and auto matically triggers the pll when the xo signal is stable. to manually control the startup time, the us er should either wait for ts_osc max, or monitor the signal clkout which will only be made available on the output buffer when a stable xo oscillation is achieved. an external clock can be used to replace the crystal oscillat or, for instance a tight tolerance tcxo. to do so, bit 4 at address 0x59 should be set to 1, and the external clock has to be provided on xta (pin 4). xtb (pin 5) should be left open. the peak-peak amplitude of the input signal must never exceed 1.8 v. please consult your tcxo supplier for an appropriate value of decoupling capacitor, c d . figure 4. tcxo connection xta xtb 32 mhz tcxo nc op vcc gnd c d vcc
www.semtech.com page 16 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 3.3.2. clkout output the reference frequency, or a fraction of it, can be provided on dio5 (pin 12) by modifying bits clkout in regdiomapping2 . two typical applications of the clkout output include: ? to provide a clock output for a companion processor, thus sa ving the cost of an addition al oscillator. clkout can be made available in any operation mode except sleep mode and is automatically enabled at power on reset. ? to provide an oscillator reference output . measurement of the clkout signal enab les simple software trimming of the initial crystal tolerance. note to minimize the current consumpti on of the sx1239, please ensure that t he clkout signal is disabled when not required. 3.3.3. pll architecture the frequency synthesizer generating the lo frequency for th e receiver is a fractional-n sigma-delta pll. the pll incorporates a third order loop capable of fast auto-calibration, and it has a fast switching-time. the vco and the loop filter are both fully integrated, removing the need for an external tight-tolerance, high-q inductor in the vco tank circuit. 3.3.3.1. vco the vco runs at 2, 4 or 6 times the rf frequency (respectively in the 915, 434 and 315 mhz bands) to reduce any lo leakage in receiver mode, to improve the quadrature precision of the receiver. the vco calibration is fully automated. a coarse adjustment is carried out at power on reset, and a fine tuning is performed each time the sx1239 pll is activated. automatic calib ration times are fully transparent to the end-user, as their processing time is included in the ts_re specifications. 3.3.3.2. pll bandwidth the bandwidth of the sx1239 fractional-n pll is wide enough to allow for very fast pll lock times, enabling both short startup and fast hop times required for frequency agile applications. 3.3.3.3. carrier frequency and resolution the sx1239 pll embeds a 19-bit sigma-delta modulator and it s frequency resolution, constant over the whole frequency range, and is given by: the carrier frequency is programmed through regfrf , split across addresses 0x07 to 0x09: note the frf setting is split across 3 bytes. a change in the center frequenc y will only be taken into account when the least significant byte frflsb in regfrflsb is written. f step f xosc 2 19 ---------------- = f rf f step frf 23 0 (,) =
www.semtech.com page 17 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 3.3.4. lock time pll lock time ts_fs is a function of a number of technical factors, such as synthesized frequency, frequency step, etc. when using the built-in sequencer, the sx1239 optimizes the star tup time and automatically st arts the receiver when the pll has locked. to manually control the star tup time, the user should either wait for ts_fs max given in the specification, or monitor the signal pll lock detect indicator, whic h is set when the pll has is within its locking range. when performing an afc, which usually corrects very small frequency errors, the pll response time is approximately: in a frequency hopping scheme, the timings ts_hop given in the table of specifications give an order of magnitude for the expected lock times. 3.3.5. lock detect indicator a lock indication signal can be made available on some of the dio pins, and is toggled high when the pll reaches its locking range. please refer to table 17 and table 18 to map this interrupt to the desired pins. 3.4. receiver description the sx1239 features a digital receiver wit h the analog to digital conversion proc ess being performed di rectly following the lna-mixers block. the zero-if receiver is able to handle (g)fsk and (g)msk modulation. ask and ook modulation is, however, demodulated by a low-if architecture. all the filter ing, demodulation, gain control, synchronization and packet handling is performed digitally, which allows a very wide range of bit rates and frequency deviations to be selected. the receiver is also capable of automa tic gain calibration in order to im prove precision on rssi measurements. 3.4.1. block diagram figure 5. receiver block diagram the following sections give a brief description of each of the receiver blocks. t pllafc 5 pllbw ------------------- - = lna single to differential mixers / modulators decimator rssi afc rfin fsk demodulator local oscillator channel filter dc cancellation rx calibration reference bypassed in fsk phase output module output complex filter cordic ook demodulator processing agc
www.semtech.com page 18 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 3.4.2. lna - single to differential buffer the lna uses a common-gate topology, which allows for a fl at characteristic over the whole frequency range. it is designed to have an input impedance of 50 oh ms or 200 ohms (as selected with bit lnazin in reglna) , and the parasitic capacitance at the lna input port is cance lled with the external rf choke. a single to differential buffer is implemented to improve the second order linearity of the receiver. the lna gain, including the single-to-differential buffer, is programmable over a 48 db dyna mic range, and control is either manual or automatic with th e embedded agc function. note in the specific case where the lna ga in is manually set by the user, the rece iver will not be able to properly handle fsk signals with a modulation index smaller than 2 at an input power greater than the 1db compression point, tabulated in section 3.4.3. table 8 lna gain settings 3.4.3. automatic gain control by default ( lnagainselect = 000 ), the lna gain is controlled by a digital agc loop in order to obtain the optimal sensitivity/ linearity trade-off. regardless of the data transfer mode (packet or continuous ), the following series of event s takes place when the receiver is enabled: ? the receiver stays in wait mode, until rssivalue exceeds rssithreshold for two consecutive samples. its power consumption is the receiver power consumption. ? when this condition is satisfied, the receiver automatically selects the most suitable lna gain, optimizing the sensitivity/ linearity trade-off. ? the programmed lna gain, read-accessible with lnacurrentgain in reglna , is carried on for the whole duration of the packet, until one of the followi ng conditions is fulfilled: ? packet mode: if autorxrestarton = 0, the lna gain will remain the same for th e reception of the following packet. if autorxrestarton = 1 , after the controller has emptie d the fifo the receiver will re- enter the wait mode described above, after a delay of interpacketrxdelay , allowing for the distant transmitter to ramp down, hence avoiding a false rssi detection. in both cases (autorxr estarton=0 or autorxrestarton=1), the receiver can also re-enter the wait mode by setting restartrx bit to 1. the user can decide to do so, to manually launch a new agc procedure. ? continuous mode: upon reception of valid data, the user can decide to either leave the receiver enabled with the same lna gain, or to restart the procedure, by setting restartrx bit to 1, resuming the wait mode of the receiver, described above. notes - the agc procedure must be performed while receiving preamble in fsk mode - in ook mode, the agc will give better results if performed while re ceiving a constant ?1? sequence lnagainselect lna gain gain setting 000 any of the below, set by the agc loop - 001 max gain g1 010 max gain - 6 db g2 011 max gain - 12 db g3 100 max gain - 24 db g4 101 max gain - 36 db g5 110 max gain - 48 db g6 111 reserved -
www.semtech.com page 19 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 the following figure illust rates the agc behavior: : figure 6. agc thresholds settings the following table summarizes the performance (typical figures) of the complete receiver: table 9 receiver performance summary 3.4.3.1. rssithreshold setting for correct operation of the agc, rssithreshold in regrssithresh must be set to the sensit ivity of the receiver. the receiver will remain in wait mode until rssithreshold is exceeded. note when afc is enabled and performed automatically at the receiver startup, the channel filter used by the receiver during the afc and the agc is rxbwafc instead of the stand ard rxbw setting. this may impact the sensitivity of the receiver, and the setting of rssithreshold accordingly 3.4.3.2. agc reference the agc reference level is automatically computed in the sx1239, according to: agc reference [dbm] = -174 + nf + demodsnr +10.log(2* rxbw ) + fadingmargin [dbm] input power pin gain setting receiver performance (typ) p -1db [dbm] nf [db] iip3 [dbm] iip2 [dbm] pin < agcthresh1 g1 -37 7 -18 +35 agcthresh1 < pin < agcthresh2 g2 -31 13 -15 +40 agcthresh2 < pin < agcthresh3 g3 -26 18 -8 +48 agcthresh3 < pin < agcthresh4 g4 -14 27 -1 +62 agcthresh4 < pin < agcthresh5 g5 >-6 36 +13 +68 agcthresh5 < pin g6 >0 44 +20 +75 towards -125 dbm ? a g c r e f e r e n c e ? a g c t h r e s h 1 ? a g c t h r e s h 2 ? a g c t h r e s h 3 ? a g c t h r e s h 4 pin [dbm] ? a g c t h r e s h 5 16db 7db 11db 9db 11db g1 g2 g3 g4 g5 g6 higher sensitivity lower linearity lower noise figure lower sensitivity higher linearity higher noise figure
www.semtech.com page 20 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 with: ? nf = 7db : lna?s noise figure at maximum gain ? demodsnr = 8 db : snr needed by the demodulator ? rxbw : single sideband channel filter bandwidth ? fadingmargin = 5 db : fading margin 3.4.4. continuous-time dagc in addition to the automatic gain control described in section 3.4.3, the sx1239 is capable of continuously adjusting its gain in the digital domain, after the analog to digital conversion ha s occured. this feature, name d dagc, is fully transparent to the end user. the digital gain adjustment is repea ted every 2 bits, and has the following benefits: ? fully transparent to the end user ? improves the fading margin of the receiver during the rece ption of a packet, even if the gain of the lna is frozen ? improves the receiver robustness in fast fading signal condit ions, by quickly adjusting the receiver gain (every 2 bits) ? works in continuous, packet, and unlimited length packet modes the dagc is enabled by setting regtestdagc to 0x10 for low modulation index systems (i.e. when afclowbetaon =1, refer to section 3.4.17), and 0x30 for other systems. see sect ion 9.5 for details. it is recommended to always enable the dagc. 3.4.5. quadrature mixer - adcs - decimators the mixer is inserted between output of the rf buffer stage and the input of the analog to digital converter (adc) of the receiver section. this block is designed to translate the spectr um of the input rf signal to base-band, and offer both high iip2 and iip3 responses. in the lower bands of operation (290 to 510 mhz), the multi- phase mixing architecture with weighted phases improves the rejection of the lo harmonics in receiver mode, hence incr easing the receiver immunity to out-of-band interferers. the i and q digitalization is made by two 5 th order continuous-time sigma-delta anal og to digital converters (adc). their gain is not constant over temperature, but the whole receiver is calibrated before reception, so that this inaccuracy has no impact on the rssi precision. the adc output is one bit per channel. it needs to be decimated and filtered afterwards. this adc can also be used for temperature measurement, please refer to section 3.4.18 for more details. the decimators decrease the sample rate of the incoming si gnal in order to optimize the area and power consumption of the following receiver blocks. 3.4.6. channel filter the role of the channel filter is to filt er out the noise and interferers outside of the channel. channel filtering on the sx12 39 is implemented with a 16-tap finite impulse response (fir) filter, providing an outstandi ng adjacent chan nel rejection performance, even for narrowband applications. note to respect oversampling rules in the decimation chain of the receiver, the bit rate cannot be set at a higher value than 2 times the single-side receiv er bandwidth (bit rate < 2 x rxbw) the single-side channel filter bandwidth rxbw is controlled by the parameters rxbwmant and rxbwexp in regrxbw:
www.semtech.com page 21 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 ? when fsk modulation is enabled: ? when ook modulation is enabled: the following channel filter b andwidths are accessible (oscilla tor is mandated at 32 mhz): table 10 available rxbw settings 3.4.7. dc cancellation dc cancellation is required in ze ro-if architecture receivers to remove any dc offset generated through self-reception. it is built-in the sx1239 and its adjustable cutoff frequency fc is controlled in regrxbw : rxbwmant (binary/value) rxbwexp (decimal) rxbw (khz) fsk modulationtype=00 ook modulationtype=01 10b / 24 7 2.6 1.3 01b / 20 7 3.1 1.6 00b / 16 7 3.9 2.0 10b / 24 6 5.2 2.6 01b / 20 6 6.3 3.1 00b / 16 6 7.8 3.9 10b / 24 5 10.4 5.2 01b / 20 5 12.5 6.3 00b / 16 5 15.6 7.8 10b / 24 4 20.8 10.4 01b / 20 4 25.0 12.5 00b / 16 4 31.3 15.6 10b / 24 3 41.7 20.8 01b / 20 3 50.0 25.0 00b / 16 3 62.5 31.3 10b / 24 2 83.3 41.7 01b / 20 2 100.0 50.0 00b / 16 2 125.0 62.5 10b / 24 1 166.7 83.3 01b / 20 1 200.0 100.0 00b / 16 1 250.0 125.0 10b / 24 0 333.3 166.7 01b / 20 0 400.0 200.0 00b / 16 0 500.0 250.0 rxbw fxosc rxbwmant 2 rxbwexp 2 + ----------------------------------------------------------------- - = rxbw fxosc rxbwmant 2 rxbwexp 3 + ----------------------------------------------------------------- - =
www.semtech.com page 22 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 the default value of dccfreq cutoff frequency is typically 4% of the rxbw (channel filter bw). the cutoff frequency of the dcc can however be increased to slightly im prove the sensitivity, under wider modulation condit ions. it is advised to adjust the dcc setting while monitori ng the receiver sensitivity. 3.4.8. complex filter - ook in ook mode the sx1239 is modified to a lo w-if architecture. the if frequency is automatically set to half the single side bandwidth of the channel filter (f if = 0.5 x rxbw ). the local oscillator is automatically offset by the if in the ook receiver. a complex filter is implemented on the chip to attenu ate the resulting image frequency by typically 30 db. note this filter is au tomatically bypassed when receivin g fsk signals (modulationtype = 00 in regdatamodul). 3.4.9. rssi the rssi block evaluates the amount of en ergy available within the receiver channel bandwidth. its resolution is 0.5 db, and it has a wide dynamic range to accommodate both small an d large signal levels that may be present. its acquisition time is very short, taking only 2 bit periods. the rssi sampli ng must occur during the reception of preamble in fsk, and constant ?1? reception in ook. note - the receiver is capable of automati c gain calibration, in order to improve the precision of its rssi measurements. this function injects a known rf signal at the lna in put, and calibrates the receiver gain accordingly. this calibration is automatically performed during the pll star t-up, making it a transparent process to the end-user. - rssivalue can only be read when it exceeds rssithreshold 3.4.10. cordic the cordic task is to extract the phase and the amplitude of the modulation vect or (i+j.q). this information, still in the digital domain is used: ? phase output: used by the fsk demodulator and the afc blocks. ? amplitude output: used by the rssi block, for fsk demo dulation, agc and automatic gain calibration purposes. figure 7. cordic extraction 3.4.11. bit rate setting fc 4 rxbw 2 2 dccfreq 2 + ----------------------------------------- - = i(t) q(t) real-time phase real-time magnitude
www.semtech.com page 23 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 the bit rate (br) is controlled by bits bitrate in regbitrate : amongst others, the following bit rates are accessible: table 11 bit rate examples 3.4.12. fsk demodulator the fsk demodulator of the sx1239 is designed to demodulate fsk, gfsk, msk and gmsk modulated signals. it is most efficient when the modulation index of the signal is greater than 0.5 and below 10: the output of the fsk demodulator can be fed to the bit sync hronizer (described in section 3.4.14), to provide the companion processor with a synchronous data stream in continuous mode. type bitrate (15:8) bitrate (7:0) (g)fsk (g)msk ook actual br (b/s) classical modem baud rates (multiples of 1.2 kbps) 0x68 0x2b 1.2 kbps 1.2 kbps 1200.015 0x34 0x15 2.4 kbps 2.4 kbps 2400.060 0x1a 0x0b 4.8 kbps 4.8 kbps 4799.760 0x0d 0x05 9.6 kbps 9.6 kbps 9600.960 0x06 0x83 19.2 kbps 19.2 kbps 19196.16 0x03 0x41 38.4 kbps 38415.36 0x01 0xa1 76.8 kbps 76738.60 0x00 0xd0 153.6 kbps 153846.1 classical modem baud rates (multiples of 0.9 kbps) 0x02 0x2c 57.6 kbps 57553.95 0x01 0x16 115.2 kbps 115107.9 round bit rates (multiples of 12.5, 25 and 50 kbps) 0x0a 0x00 12.5 kbps 12.5 kbps 12500.00 0x05 0x00 25 kbps 25 kbps 25000.00 0x02 0x80 50 kbps 50000.00 0x01 0x40 100 kbps 100000.0 0x00 0xd5 150 kbps 150234.7 0x00 0xa0 200 kbps 200000.0 0x00 0x80 250 kbps 250000.0 0x00 0x6b 300 kbps 299065.4 watch xtal frequency 0x03 0xd1 32.768 kbps 32.768 kbps 32753.32 br f xosc bitrate ------------------- - = 0.5 2 f dev br ---------------------- 10 =
www.semtech.com page 24 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 3.4.13. ook demodulator the ook demodulator performs a comparison of the rssi outpu t and a threshold value. three different threshold modes are available, configured through bits ookthreshtype in regookpeak . the recommended mo de of operation is th e "peak" threshold mode, illustrated in figure 8: figure 8. ook peak demodulator description in peak threshold mode the comparison threshold level is the peak value of the rssi, reduced by 6db. in the absence of an input signal, or during the reception of a logical "0", the acquired peak value is decremented by one ookpeakthreshstep every ookpeakthreshdec period. when the rssi output is null for a long time (for instance after a long string of "0" received, or if no transmitter is present ), the peak threshold level will continue falling until it reaches the "f loor threshold", programmed in ookfixedthresh . the default settings of the ook demodulator lead to the perfor mance stated in the electrical specification. however, in applications in which sudden signal drops are awaited duri ng a reception, the three parameters should be optimized accordingly. 3.4.13.1. optimizing the floor threshold ookfixedthresh determines the sensitivity of the ook receiver, as it sets the comparison threshold for weak input signals (i.e. those close to the noise floor). significant sensitiv ity improvements can be gener ated if configured correctly. zoom period as defined in ookpeakthreshdec decay in db as defined in ookpeakthreshstep fixed 6db difference rssi [dbm] noise floor of receiver ??floor?? threshold defined by ookfixedthresh time ??peak -6db?? threshold zoom
www.semtech.com page 25 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 note that the noise floor of the receiver at the demodulator input depends on: ? the noise figure of the receiver. ? the gain of the receive chain from antenna to base band. ? the matching - including saw filter if any. ? the bandwidth of the channel filters. it is therefore important to note that the setting of ookfixedthresh will be application dependa nt. the following procedure is recommended to optimize ookfixedthresh . figure 9. floor threshold optimization the new floor threshold value found during this test should be used for ook reception wi th those receiver settings. 3.4.13.2. optimizing ook demodul ator for fast fading signals a sudden drop in signal strength can cause the bit error rate to increase. for applications where the expected signal drop can be estimated, the following ook demodulator parameters ookpeakthreshstep and ookpeakthreshdec can be optimized as described below for a given number of threshold decrements per bit. refer to regookpeak to access those settings. 3.4.13.3. alternative ook demodulator threshold modes in addition to the peak ook threshold mode, the user can alternatively select two other types of threshold detectors: ? fixed threshold: the value is selected through ookfixedthresh ? average threshold: data supplied by the rssi block is av eraged, and this operation mode should only be used with dc-free encoded data. set sx1239 in ook rx mode adjust bit rate, channel filter bw default ookfixedthresh setting no input signal continuous mode optimization complete glitch activity on data ? monitor dio2/data pin increment ookfixedthresh
www.semtech.com page 26 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 3.4.14. bit synchronizer the bit synchronizer is a block that provi des a clean and synchronized digital output, free of glitches. its output is made available on pin dio1/dclk in continuous mode and can be di sabled through register settings. however, for optimum receiver performance its use when running continuous mode is strongly advised. the bit synchronizer is automatically activated in packet mode. its bit rate is controlled by bitratemsb and bitratelsb in regbitrate. figure 10. bit synchronizer description to ensure correct operation of the bit synchronizer , the following conditions have to be satisfied: ? a preamble (0x55 or 0xaa) of 12 bits is required for synchronization (from the rxready interrupt) ? the subsequent payload bit stream must have at least one tran sition form '0' to '1' or '1' to '0 every 16 bits during data transmission ? the bit rate matching between the transmitter and the receiver must be better than 6.5 %. notes - if the bit rates of transmitter and receiver are known to be the same , the sx1239 will be able to receive an infinite unbalanced sequence (all ?0s? or all ?1s?) with no restriction. - if there is a difference in bit rate between tx and rx, the amount of adjacent bits at the same level that the bitsync can withstand can be estimated as follows: - this implies approximately 6 consecut ive unbalanced bytes when the bit rate precision is 1%, which is easily achievable (crystal tolerance is in the range of 50 to 100 ppm). 3.4.15. frequency error indicator this function provides information about the frequ ency error of the local oscillator (lo) compared with the carrier frequency of a modulated signal at the input of the receiver. when the fe i block is launched, the frequency error is measured and the raw demodulator output (fsk or ook) dclk data bitsync output to pin data and dclk in continuous mode
www.semtech.com page 27 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 signed result is loaded in feivalue in regfei , in 2?s complement format. the time required for an fei evaluation is 4 times the bit period. to ensure a proper behavior of the fei: ? the operation must be done during the reception of preamble ? the sum of the frequency offset and the 20 db signal b andwidth must be lower than the base band filter bandwidth the 20 db bandwidth of the signal can be evaluated as follows (double-side bandwidth): the frequency error, in hz, can be calculated with the following formula: figure 11. fei process 3.4.16. automatic frequency correction the afc is based on the fei block, and therefore the same input signal and receiver setting conditions apply. when the afc procedure is done, afcvalue is directly subtracted to the register that defines the frequency of operation of the chip, f rf . the afc can be launched: ? each time the receiver is enabled, if afcautoon = 1 ? upon user request, by setting bit afcstart in regafcfei , if afcautoon = 0 bw 20 db 2 f dev br 2 ------- + ?? ?? = fei f step feivalue = sx1239 in rx mode preamble-modulated input signal signal level > sensitivity set feistart = 1 feidone = 1 no yes read feivalue
www.semtech.com page 28 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 when the afc is automatically triggered ( afcautoon = 1), the user has the option to: ? clear the former afc correction value, if afcautoclearon = 1 ? start the afc evaluation from the previously corrected frequen cy. this may be useful in sys tems in which the lo keeps on drifting in the ?same direction?. ageing compensation is a good example. the sx1239 offers an alternate receiver bandwidth setting during the afc phase, to accommodate large lo drifts. if the user considers that the received signal may be out of th e receiver bandwidth, a higher channel filter bandwidth can be programmed in regafcbw , at the expense of the receiver noise floor, whic h will impact upon sensitivity. 3.4.17. optimized setup for low modulation index systems ? for wide band systems, where afc is usually not required (xtal inaccuracies do not typically impact the sensitivity), it is recommended to offset the lo frequency of the receiver to avoid desensitization. th is can be simply done by modifying frf in regfrflsb . a good rule of thumb is to offset the rece iver?s lo by 10% of the expected transmitter frequency deviation. ? for narrow band systems, it is recommended to perf orm afc. the sx1239 has a dedicated afc, enabled when afclowbetaon in regafcctrl is set to 1. a frequency offset, programmable through lowbetaafcoffset in regtestafc , is added and is calculated as follows: offset = lowbetaafcoffset x 488 hz the user should ensure that the progr ammed offset exceeds the dc canceller?s cutoff frequency, set through dccfreqafc in regafcbw. figure 12. optimized afc (afclowbetaon=1) as shown on figure 12, a standard afc sequence uses the re sult of the fei to correct t he lo frequency and align both local oscillators. when the optimized afc is enabled ( afclowbetaon=1 ), the receiver?s lo is corrected by ? feivalue + lowbetaafcoffset ?. when the optimized afc routine is enabled, the receiver startu p time can be computed as follows (refer to section 4.2.1): ts_re_agc&afc (optimized afc) = tana + 4.tcf + 4.tdcc + 3.trssi + 2.tafc + 2.tpllafc f tx rx f rx & tx standard afc afclowbetaon = 0 f tx rx tx rx lowbetaafcoffset f afcvalue afcvalue feivalue feivalue optimized afc afclowbetaon = 1 before afc after afc
www.semtech.com page 29 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 3.4.18. temperature sensor when temperature is measured, the receiv er adc is used to digitize the sens or response. most receiver blocks are disabled, and temperature measurement can only be triggered in standby or frequency synthesizer modes. the response of the temperature sensor is -1c / lsb. a cmos temperature sensor is not ac curate by nature, therefore it should be calibrated at ambient temperature for precise temperature readings. figure 13. temperature sensor response it takes less than 100 microseconds for the sx1239 to evaluate the temperature (from setting tempmeasstart to 1 to tempmeasrunning reset). 3.4.19. timeout function the sx1239 includes a timeout function, whic h allows it to automatica lly shut-down the receiver after a receive sequence and therefore save energy. ? timeout interrupt is generated timeoutrxstart x 8 x tbit after switching to rx mode if rssithreshold flag does not raise within this time frame ? timeout interrupt is generated timeoutrssithresh x 8 x tbit after rssithreshold flag has been raised. this timeout interrupt can be used to warn the companion processor to shut down the receiver and return to a lower power mode. -40 c +85 c tempvalue ambient returns 150d (typ.) needs calibration tt+1 tempvalue(t) tempvalue(t)-1 -1 c/lsb
www.semtech.com page 30 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 4. operating modes 4.1. basic modes the circuit can be set in 4 different basic modes which are described in table 12. by default, when switching from a mode to another one, the sub-blocks are woken up according to a pre-defined and optimized sequence. alternatively, these operating modes can be selected directly by disabling the automatic sequencer ( sequenceroff in regopmode = 1 ). table 12 basic receiver modes 4.2. automatic sequencer and wake-up times by default, when switching from one operat ing mode to another, the circuit takes care of the sequence of events in such a way that the transition timing is optimized. for example, when switching from sleep mode to receive mode, the sx1239 goes first to standby mode (xo started), then to frequency synthesizer mode, and finally, when the pll has locked, to receive mode. ? the crystal oscillator wake-up time, ts_osc , is directly related to the time for th e crystal oscillator to reach its steady state. it depends notably on the crystal characteristics. ? the frequency synthesizer wake-up time, ts _fs, is directly related to the time needed by the pll to reach its steady state. the signal pll_lock, provided on an external pin, give s an indication of the lock status. it goes high when the pll reaches its locking range. three specific cases can be highlighted: ? receiver wake up time from sleep mode = ts_osc + ts_fs + ts_re ? receiver wake up time from sleep mode, agc enabled = ts_osc + ts_fs + ts_re_agc ? receiver wake up time from sleep mode, agc and afc enabled = ts_osc + ts_fs + ts_re_agc&afc these timings are detailed in section 4.2.1. in applications where the target average power consumption, or the target startup time, do not require setting the sx1239 in the lowest power modes (sleep or standby), the respective timings ts_osc and ts_fs in the former equations can be omitted. 4.2.1. receiver startup time it is highly recommended to use the built -in sequencer of the sx1239, to optimi ze the delays when setting the chip in receive mode. it guarantees the shortest startup times, he nce the lowest possible energy usage, for battery operated systems. the startup times of the receiver can be calculated from the following: listenon in regopmode mode in regopmode selected mode enabled blocks 0 0 0 0 sleep mode none 0 0 0 1 stand-by mode top regulator and crystal oscillator 0 0 1 0 fs mode frequency synthesizer 0 1 0 0 receive mode frequency synthesizer and receiver 1 x listen mode see listen mode, section 4.3
www.semtech.com page 31 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 figure 14. rx startup - no agc, no afc figure 15. rx startup - agc, no afc figure 16. rx startup - agc and afc the different timings shown above are as follows: ? group delay of the analog front en d: tana = 20 us ? channel filter?s group delay in fsk mode: tcf = 21 / (4.rxbw) ? channel filter?s group delay in ook mode: tcf = 34 / (4.rxbw) ? dc cutoff?s group delay: tdcc = max(8 , 2^(round(log2(8.rxbw.tbit)+1)) / (4.rxbw) ? pll lock time after afc adjustment: tpllafc = 5 / pllbw (pllbw = 300 khz) ? afc sample time: tafc = 4 x tbit (also denoted ts _afc in the general specification) ? rssi sample time: trssi = 2 x int(4.rxbw.tbit)/(4.rxbw) (aka ts_rssi) note the above timings represent maximum settling times, an d shorter settling times may be observed in real cases analog fe?s group delay channel filter?s group delay dc cutoff?s group delay rssi sampling xo started and pll is locked tana rssi sampling tcf tdcc trssi trssi reception of packet modeready rxready ts_re rx startup request (sequencer or user) analog fe?s group delay channel filter?s group delay dc cutoff?s group delay rssi sampling xo started and pll is locked tana rssi sampling tcf tdcc trssi trssi reception of packet modeready rxready channel filter?s group delay dc cutoff?s group delay rssi sampling tcf tdcc trssi the lna gain is adjusted by the agc, according to the rssi result ts_re_agc rx startup request (sequencer or user) analog fe?s group delay channel filter?s group delay dc cutoff?s group delay rssi sampling xo started and pll is locked tana rssi sampling tcf tdcc trssi trssi reception of packet modeready rxready channel filter?s group delay dc cutoff?s group delay rssi sampling tcf tdcc trssi afc tafc pll lock tpllafc channel filter?s group delay tcf dc cutoff?s group delay tdcc ts_re_agc&afc rx startup request (sequencer or user) the lna gain is adjusted by the agc, according to the rssi result carrier frequency is adjusted by the afc
www.semtech.com page 32 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 4.2.2. rx start procedure as described in the former sections, the rxready interrupt warns the uc that the receiver is ready. ? in continuous mode with bit synchronizer , the receiver will start locking its bit sync hronizer on a minimum or 12 bits of received preamble (see section 3.4.14 for details), before th e reception of correct data, or sync word (if enabled) can occur. ? in continuous mode without bit synchronizer , valid data will be available on dio2/data right after the rxready interrupt. ? in packet mode , the receiver will start locking its bit synchronizer on a minimum or 12 bits of received preamble (see section 3.4.14 for details), before the reception of correct data, or sync word (if enabled) can occur. 4.2.3. optimized frequency hopping sequences in a frequency hopping-like application, it is required to turn off the receiver when hopping from one channel to another, to optimize the hopping sequence: receiver hop from ch a to ch b: (0) sx1239 is in rx mode in ch a (1) change the carrier frequency in the regfrf registers (2) program the sx1239 in fs mode (3) turn the receiver back to rx mode (4) respect the rx start procedu re, described in section 4.2.4 note the above sequence assumes that the sequencer is turned on (sequenceroff=0 in regopmode).
www.semtech.com page 33 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 4.3. listen mode the circuit can be set to listen mode, by setting listenon in regopmode to 1 while in standby mode. in this mode, sx1239 spends most of the time in idle mode, during which only the rc oscillator runs. periodically the receiver is woken up and listens for an rf signal. if a wanted signal is dete cted, the receiver is kept on and the data is demodulated. otherwise, if a wanted signal hasn't been de tected after a pre-defined period of time , the receiver is disabled until the next time period. this periodical rx wake-up requirement is very common in low power applications. on sx1239 it is handled locally by the listen mode block without using uc resources or energy. the simplified timing diagram of this procedure is illustrated in figure 17. figure 17. listen mode sequence (no wanted signal is received) 4.3.1. timings the duration of the idle phase is given by t listenidle . the time during which the receiver is on and waits for a signal is given by t listenrx . t listenrx includes the wake-up time of the receiver, de scribed in section 4.2.1. this duration can be programmed in the configuration registers via the serial interface. both time periods t listenrx and t listenidle (denoted t listenx in the following text) are fixe d by two parameters from the configuration register and are calculated as follows: where listenresolx is the rx or idle resolution and is independ antly programmable on thr ee values (64us, 4.1ms or 262ms), whereas listencoefx is an integer between 1 and 255. all parameters are located in reglisten registers. the timing ranges are tabulated in table 13 below. table 13 range of durations in listen mode listenresolx min duration ( listencoef = 1 ) max duration ( listencoef = 255 ) 01 64 us 16 ms 10 4.1 ms 1.04 s 11 0.26 s 67 s time t listenidle t listenrx t listenrx idle rx rx solx listen x listencoef t listenx re ? =
www.semtech.com page 34 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 notes - the accuracy of the typical timings given in table 13 will depend in the rc oscillator calibration - rc oscillator calibration is require d, and must be performe d at power up. see section 4.3.4 for details 4.3.2. criteria the criteria taken for detecting a wanted signal and henc e deciding to maintain the receiver on is defined by listencriteria in reglisten1. table 14 signal acceptance criteria in listen mode 4.3.3. end of cycle actions the action taken after detection of a packet, is defined by listenend in reglisten3 , as described in the table below. table 15 end of listen cycle actions listencriteria input signal power >= rssithreshold syncaddressmatch 0 required not required 1 required required listenend description 00 chip stays in rx mode. listen mode stops and must be disabled. 01 chip stays in rx mode until payloadready or timeout interrupt occurs. it then goes to the mode defined by mode . listen mode stops and must be disabled. 10 chip stays in rx mode until payloadready or timeout interrupt occurs. listen mode then resumes in idle state. fifo cont ent is lost at next rx wakeup.
www.semtech.com page 35 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 upon detection of a valid packet, the sequencing is altered, as shown below: figure 18. listen mode sequence (wanted signal is received) listen mode can be disabled by writing listenon to 0 4.3.4. rc timer accuracy all timings of the listen mode rely on the accuracy of the internal low-power rc oscillator. this oscillator is automatically calibrated at the device power-up, and it is a user-transparent process. for applications enduring large temperature variations, and fo r which the power supply is never removed, rc calibration can be performed upon user request. rccalstart in regosc1 can be used to trigger this calibration, and the flag rccaldone will be set automatically when the calibration is over. payloadready listencriteria passed listen mode idle rx listen mode listen mode idle rx mode idle rx idle rx listenend = 00 listenend = 01 listenend = 10
www.semtech.com page 36 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 4.4. automodes automatic modes of packet handler can be enabled by configuring the related parameters in regautomodes . the intermediate mode of the chip is called intermediatemode and the enter and exit conditions to/from this intermediate mode can be configured through the parameters entercondition & exitcondition . the enter and exit conditions cannot be used independently of each other i.e. both should be enabled at the same time. the initial and the final state is the one configured in the mode in regopmode . the initial & final states can be different by configuring the modes register while the chip is in intermediat e mode. the pictorial description of the auto modes is shown below. figure 19. auto modes of packet handler some typical examples of automodes usage are described below : ? automatic reception (autorx) : mode = rx, intermediatemode = sleep, entercondition = crcok , exitcondition = falling edge of fifonotempty ? ... initial state defined by m ode in regopmode intermediate state defined by intermediatemode exitcondition entercondition final state defined by m ode in regopmode
www.semtech.com page 37 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 5. data processing 5.1. overview 5.1.1. block diagram figure below illustrates the sx1239 data processing circuit. its role is to interface the data from the demodulator and the uc access points (spi and dio pins). it also controls all the configuration registers. the circuit contains several control blocks wh ich are described in the following paragraphs. figure 20. sx1239 data processing conceptual view the sx1239 implements several data operation modes, each with their own data path through the data processing section. depending on the data operation mode selected, some cont rol blocks are active whilst others remain disabled. 5.1.2. data operation modes the sx1239 has two different data operation modes selectable by the user: ? continuous mode: each bit received is accessed in real time at th e dio2/data pin. this mode may be used if adequate external signal processing is available. ? packet mode (recommended): user only retrieves payload bytes from the fifo. the packet engine automatically removes the preamble, checks the sy nc word, performs aes decryption, ch ecks the crc, and decodes dc-free schemes if enabled. the uc processing overhead is henc e significantly reduced compared to continuous mode. depending on the optional feat ures activated (crc, aes, etc) the maximum payload length is limited to fifo size, 255 bytes or unlimited. each of these data operation modes is described fully in the following sections. control spi packet handler sync recog. dio1 miso mosi sck nss rx rx data fifo (+sr) potential datapaths (data operation mode dependant) dio2 dio0 dio3 dio4 dio5
www.semtech.com page 38 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 5.2. control block description 5.2.1. spi interface the spi interface gives access to the configuration register via a synchronous full-duplex pr otocol corresponding to cpol = 0 and cpha = 0 in motorola/freescale nome nclature. only the slave side is implemented. three access modes to the registers are provided: ? single access: an address byte followed by a data byte is sent for a write access whereas an address byte is sent and a read byte is received for the read access. the nss pin goes low at the begin of the frame and goes high after the data byte. ? burst access: the address byte is followed by several data bytes. the address is automati cally incremented internally between each data byte. this mode is available for both read and write accesses. the nss pin goes low at the beginning of the frame and stay low between each byte . it goes high only afte r the last byte transfer. ? fifo access: if the address byte corr esponds to the address of the fifo, then succeeding data byte will address the fifo. the address is not automatically incremented but is me morized and does not need to be sent between each data byte. the nss pin goes low at the beginning of the frame and stay low between each byte. it goes high only after the last byte transfer. figure below shows a typical spi single access to a register. figure 21. spi timing diagram (single access) mosi is generated by th e master on the falling edge of sck and is sample d by the slave (i.e. this spi interface) on the rising edge of sck. miso is generated by the slav e on the falling edge of sck. a transfer always starts by the nss pin going lo w. miso is high impedance when nss is high. the first byte is the address byte. it is made of: ? wnr bit, which is 1 for write access and 0 for read access ? 7 bits of address, msb first the second byte is a data byte, either se nt on mosi by the master in case of a write access, or received by the master on miso in case of read access. the data byte is transmitted msb first. proceeding bytes may be sent on mosi (for write access) or received on miso (for read access) without rising nss and re-sending the address. in fifo mode, if the address was t he fifo address then the bytes will be read at the fifo address. in burst mode, if the address was not the fifo addr ess, then it is automatically incremented at each new byte received.
www.semtech.com page 39 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 the frame ends when nss goes high. the next frame must start with an address byte. the single access mode is actually a special case of fifo / burst mode with only 1 data byte transferred. during the write access, the byte transferred from the slave to the master on the miso line is the value of the written register before the write operation. 5.2.2. fifo 5.2.2.1. overview and shift register (sr) in packet mode of operation, data that has been received is stored in a configurable fifo (first in first out) device. it is accessed via the spi interface and provides several interrupts for transfer management. the fifo is 1 byte wide hence it only performs byte (paralle l) operations, whereas the demodulator functions serially. a shift register is therefore employed to interface the two device s. in rx the shift register gets bit by bit data from the demodulator and writes them byte by byte to the fifo. this is illustrated in figure 22. figure 22. fifo and shift register (sr) note when switching to sleep mode, the fifo can only be us ed once the modeready flag is set (quasi immediate from all modes) 5.2.2.2. size the fifo size is fixed to 66 bytes. 5.2.2.3. interrupt sources and flags ? fifonotempty : fifonotempty interrupt source is lo w when byte 0, i.e. wh ole fifo, is empty. otherwise it is high. note that when retrieving data from the fifo, fifonotempty is updated on nss fa lling edge, i.e. when fifonotempty is updated to low state the currently started read operation must be completed. in other words, fifonotempty state must be checked after each read operation for a decision on the next one ( fifonotempty = 1: more byte(s) to read; fifonotempty = 0: no more byte to read). ? fifofull : fifofull interrupt source is high when the last fifo byte, i.e. the w hole fifo, is full. ot herwise it is low. ? fifooverrunflag : fifooverrunflag is set when a new byte is written by the sr while the fifo is already full. data is lost and the flag should be cleare d by writing a 1, note that the fifo will also be cleared. ? fifolevel : threshold can be programmed by fifothreshold in regfifothresh . its behavior is illust rated in figure below. rx data 8 1 sr (8bits) byte0 byte1 fifo msb lsb
www.semtech.com page 40 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 figure 23. fifolevel irq source behavior 5.2.2.4. fifo clearing table below summarizes the status of the fi fo when switching between different modes table 16 status of fifo when switching between different modes of the chip 5.2.3. sync word recognition 5.2.3.1. overview sync word recognition (als o called pattern recognition) is activated by setting syncon in regsyncconfig . the bit synchronizer must also be activated in continuo us mode (automatically done in packet mode) . the block behaves like a shift register; it continuously co mpares the incoming data with its internally programmed sync word and sets syncaddressmatch when a match is detected. this is illustrated in figure 24 below. from to fifo status comments stdby sleep not cleared sleep stdby not cleared stdby/sleep rx cleared rx stdby/sleep not cleared to allow the user to read fifo in stdby/sleep mode after rx # of bytes in fifo fifolevel 0 1 b b+1
www.semtech.com page 41 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 figure 24. sync word recognition during the comparison of the demodulated data, the fi rst bit received is compared with bit 7 (msb) of regsyncvalue1 and the last bit received is compared with bit 0 (lsb) of the la st byte whose address is determ ined by the length of the sync word. when the programmed sync word is detected the user can assu me that this incoming packet is for the node and can be processed accordingly. syncaddressmatch is cleared when leaving rx or fifo is emptied. 5.2.3.2. configuration ? size: sync word size can be set from 1 to 8 bytes (i.e. 8 to 64 bits) via syncsize in regsyncconfig . ? error tolerance: the number of errors tolerated in the sync word recognition can be set from 0 to 7 bits to via synctol . ? value: the sync word va lue is configured in syncvalue(63:0) . note syncvalue choices containing 0x00 bytes are not allowed 5.2.4. packet handler the packet handler is the block used in packet mode. its functionality is fully described in section 5.5. 5.2.5. control the control block configures and controls the full chip's beha vior according to the settings programmed in the configuration registers. rx data (nrz) dclk bit n-x = sync_value[x] bit n-1 = sync_value[1] bit n = sync_value[0] syncaddressmatch
www.semtech.com page 42 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 5.3. digital io pins mapping six general purpose io pins are available on the sx1239, and their configuration in continuous or packet mode is controlled through regdiomapping1 and regdiomapping2. 5.3.1. dio pins mapping in continuous mode table 17 dio mapping, continuous mode 5.3.2. dio pins mapping in packet mode table 18 dio mapping, packet mode note received data is only shown on the data sign al between rxready and payloadready?s rising edges mode diox mapping dio5 dio4 dio3 dio2 dio1 dio0 00------ 01------ 10 lowbat lowbat automode - lowbat lowbat 11 modeready - - - - modeready 00 clkout - - - - - 01------ 10 lowbat lowbat automode - lowbat lowbat 11 modeready - - - - modeready 00 clkout - - - - plllock 01------ 10 lowbat lowbat automode - lowbat lowbat 11 modeready plllock - - plllock modeready 00 clkout timeout rssi data dclk syncaddress 01 rssi rxready rxready data rxready timeout 10 lowbat syncaddress automode data lowbat rssi 11 modeready plllock timeout data syncaddress modeready fs rx sleep stdby mode diox mapping dio5 dio4 dio3 dio2 dio1 dio0 00 - - fifofull fifonotempty fifolevel - 01 - - - - fifofull - 10 lowbat lowbat lowbat lowbat fifonotempty lowbat 11 modeready - - automode - - 00 clkout - fifofull fifonotempty fifolevel - 01 - - - - fifofull - 10 lowbat lowbat lowbat lowbat fifonotempty lowbat 11 modeready - - automode - - 00 clkout - fifofull fifonotempty fifolevel - 01 - - - - fifofull - 10 lowbat lowbat lowbat lowbat fifonotempty lowbat 11 modeready plllock plllock automode plllock plllock 00 clkout timeout fifofull fifonotempty fifolevel crcok 01 data rssi rssi data fifofull payloadready 10 lowbat rxready syncaddress lowbat fifonotempty syncaddress 11 modeready plllock plllock automode timeout rssi fs rx sleep stdby
www.semtech.com page 43 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 5.4. continuous mode 5.4.1. general description as illustrated in figure 25, in continuous mode the nrz data from the demodulator is directly accessed by the uc on the dio2/data pin. the fifo and pa cket handler are thus inactive. figure 25. continuous mode conceptual view 5.4.2. rx processing if the bit synchronizer is disabled, the raw demodulator output is made directly available on data pin and no dclk signal is provided. conversely, if the bit synchronizer is enabled, synchronous cleaned data and clock are made available respectively on dio2/data and dio1/dclk pins. data is sampled on the rising edge of dclk and updated on the falling edge as illustrated below. figure 26. rx processing in continuous mode note in continuous mode it is always recommended to enable the bit synchronizer to clean the data signal even if the dclk signal is not used by the uc (bit synchron izer is automatically enabled in packet mode). control spi sync recog. dio1/dclk miso mosi sck nss rx rx data dio2/data dio0 dio3 dio4 dio5 data (nrz) dclk
www.semtech.com page 44 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 5.5. packet mode 5.5.1. general description in packet mode the nrz data from the demodulator is not di rectly accessed by the uc but stored in the fifo and accessed via the spi interface. in addition, the sx1239 packet handler performs several packet oriented tasks such as preamble and sync word check, crc check, dewhitening of data, manchester decoding, ad dress filtering, aes decryption, et c. this simplifies software and reduces uc overhead by performing these repetitive tasks within the rf chip itself. another important feature is ability to empty the fifo in sleep/ stdby mode, ensuring optimum power consumption and adding more flexibility for the software. figure 27. packet mode conceptual view note the bit synchronizer is automa tically enabled in packet mode. 5.5.2. packet format 5.5.2.1. fixed length packet format fixed length packet format is selected when bit packetformat is set to 0 and payloadlength is set to any value greater than 0. in applications where the packet length is fixed in advance, this mode of operat ion may be of interest to minimize rf overhead (no length byte field is required). all nodes should be programmed with the same packet length value. control spi packet handler sync recog. dio1 miso mosi sck nss rx data fifo (+sr) dio2 dio0 dio3 dio4 dio5
www.semtech.com page 45 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 the length of the payload is limited to 25 5 bytes if aes is not enabled else the message is limit ed to 64 bytes (i.e. max 65 bytes payload if address byte is enabled). the length programmed in payloadlength relates only to the pa yload which includes the message and the optional address byte. in this mode, the payload must contai n at least one byte, i.e. address or message byte. an illustration of a fixed length packet is shown below. it contains the following fields: ? preamble (1010...) ? sync word (network id) ? optional address byte (node id) ? message data ? optional 2-bytes crc checksum figure 28. fixed length packet format 5.5.2.2. variable length packet format variable length packet format is selected when bit packetformat is set to 1. this mode is useful in applications where the length of the pa cket is not known in advance and can vary over time. it is then necessary for the transmitter to send the length information together with each packet in order for the receiver to operate properly. in this mode the length of the payload, indicated by the length byte, is given by the first by te of the fifo and is limited to 255 bytes if aes is not enabled else the message is limited to 64 bytes, i.e. max 66 bytes payload if address byte is enabled. note that the length by te itself is not included in its calculation. in this mode, the payload must contain at least 2 bytes, i.e. length + address or message byte. an illustration of a variable length packet is shown below. it contains the following fields: ? preamble (1010...) ? sync word (network id) ? length byte message up to 255 bytes address byte crc 2-bytes sync word 0 to 8 bytes preamble 0 to 65535 bytes payload (min 1 byte) crc checksum calculation dc free data decoding fields processed and removed in rx optional user provided fields which are part of the payload message part of the payload aes decryption
www.semtech.com page 46 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 ? optional address byte (node id) ? message data ? optional 2-bytes crc checksum figure 29. variable length packet format 5.5.2.3. unlimited length packet format unlimited length packet format is selected when bit packetformat is set to 0 and payloadlength is set to 0. the user can then receive packets of arbitrary length and payloadlength register is not used in rx modes for counting the length of the bytes received. this mode is a replacement for the legacy buffered mode in sx1211/sx1212 transceivers. the data processing features like address filtering, manches ter decoding and data dewhitening are not available if the sync pattern length is set to zero ( syncon = 0 ). the crc detection is also not supp orted in this mo de of the packet handler. the interrupts like crcok & payloadready are not available either. an unlimited length packet shown in is made up of the following fields: ? preamble (1010...). ? sync word (network id). ? optional address byte (node id). ? message data figure 30. unlimited length packet format message up to 255 bytes address byte length byte crc 2-bytes sync word 0 to 8 bytes preamble 0 to 65535 bytes payload (min 2 bytes) crc checksum calculation dc free data decoding fields processed and removed in rx optional user provided fields which are part of the payload message part of the payload aes decryption message unlimited length address byte sync word 0 to 8 bytes preamble 0 to 65535 bytes payload fields processed and removed in rx optional user provided fields which are part of the payload message part of the payload dc free data decoding
www.semtech.com page 47 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 5.5.3. processing (without aes) in rx mode the packet handler extracts the user payl oad to the fifo by performing the following operations: ? receiving the preamble and stripping it off ? detecting the sync word and stripping it off ? optional dc-free decoding of data ? optionally checking the address byte ? optionally checking crc and reflecting the result on crcok. only the payload (including optional address and length fields) is made available in the fifo. when the rx mode is enabled the demodulator receives the pr eamble followed by the detecti on of sync word. if fixed length packet format is enabled then the number of bytes received as the payload is given by the payloadlength parameter. in variable length mode the first byte receiv ed after the sync word is interpreted as the length of the received packet. the internal length counter is initializ ed to this received length. the payloadlength register is set to a value which is greater than the maximum expected length of the received packet. if th e received length is greater than the maximum length stored in payloadlength register the packet is discarded other wise the complete packet is received. if the address check is enabled then the second byte received in case of variable length and first byte in case of fixed length is the address byte. if the address matches to the one in the nodeaddress field, reception of the data continues otherwise it's stopped. the cr c check is performed if crcon = 1 and the result is available in crcok indicating that the crc was successful. an interrupt ( payloadready ) is also generated on dio0 as soon as the payload is available in the fifo. the payload available in the fifo can also be read in sleep/standby mode. if the crc fails the payloadready interrupt is not generated and the fifo is cleared. this function can be overridden by setting crcautoclearoff = 1, forcing the availability of payloadready interrupt and the payload in the fifo even if the crc fails. 5.5.4. aes aes is the symmetric-key bl ock cipher that provi des the cryptographic capabilities to the receiver. th e system proposed can work with 128-bit long fixed keys. the fixed key is stored in a 16-byte write only user configuration register, which retains its value in sleep mode. as shown in figure 28 and figure 29 above the message part of the packet can be decrypted with the cipher 128- cipher key stored in the configuration registers. 5.5.4.1. processing 1. the data received is stored in the fifo, the address , crc interrupts are generated as usual because these parameters were not encrypted. 2. once the complete packet has been received. the data is read from the fifo, decrypt ed and written back to fifo. the payloadready interrupt is issued once the decrypted data is re ady in the fifo for reading via the spi interface. the aes decryption cannot be us ed on the fly i.e. while receiving data. thus when aes decryption is enabled, the fifo acts as a simple buffer. the decryption is initiated only once the complete packet has been received in the buffer. the decryption process takes approximately 7.0 us per 16-byte bl ock. thus for a maximum of 4 blocks (i.e. 64 bytes) it can take up to 28 us for completing the cryptographic operations.
www.semtech.com page 48 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 the receiver sees the aes decryption time as a sequential delay before the payloadready interrupt is available. in fixed length mode the message part of the payload that can be decrypted can be 64 bytes lo ng. if the address filtering is enabled, the length of the payload should be at max 65 bytes in this case. in variable length mode the max message size that can be decrypted is also 64 bytes whether address comparison is enabled or not. thus, including length byte, the length of th e payload is either 65 or 66 bytes (the latter when address comparison is enabled) at max. crc check being performed on encrypted data, crcok interrupt will occur "dec ryption time" before payloadready interrupt. 5.5.5. handling large packets when payload length exceeds fifo size (66 bytes) whether in fixe d, variable or unlimited length packet format, in addition to payloadready or crcok in rx, the fifo interrupts/flags can be used as described below: fifo must be unfilled "on-the-fly" during rx to prev ent fifo overrun. 1) start reading bytes from the fifo when fifonotempty or fifothreshold becomes set. 2) suspend reading from the fifo if fifonotempty clears before all bytes of the message have been read 3) continue to step 1 until payloadready or crcok fires 4) read all remaining bytes from the fifo either in rx or sleep/standby mode note aes decryption is not feasib le on large packets, since all payload bytes need to be in the fifo at the same time to perform decryption 5.5.6. packet filtering sx1239's packet handler offers several mechanisms for packe t filtering, ensuring that only useful packets are made available to the uc, reducing significantly system power consumption and software complexity. 5.5.6.1. sync word based sync word filtering/recognition is used for identifying the start of the paylo ad and also for network identification. as previously described, the sync word recognition block is configured (size, error tolerance, value) in regsyncvalue registers. this information is us ed to filter packets in rx. every received packet which does not st art with this locally config ured sync word is autom atically discarded and no interrupt is generated. when the sync word is detected, payloa d reception automatically starts and syncaddressmatch is asserted. note sync word values containing 0x00 byte(s) are forbidden
www.semtech.com page 49 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 5.5.6.2. address based address filtering can be enabled via the addressfiltering bits. it adds another level of filt ering, above sync word (i.e. sync must match first), typically useful in a multi-node networks where a network id is shared between all nodes (sync word) and each node has its own id (address). two address based filtering options are available: ? addressfiltering = 01 : received address field is compared with internal register nodeaddress . if they match then the packet is accepted and processed, otherwise it is discarded. ? addressfiltering = 10 : received address field is compared with internal registers nodeaddress and broadcastaddress . if either is a match, the received packet is accepted and proc essed, otherwise it is discar ded. this additional check with a constant is useful for implementing broadcast in a multi-node networks as address filtering requires a sync word match, both features share th e same interrupt flag syncaddressmatch . please note that the received address byte , as part of the payload, is not stripped off the packet and is made available in the fifo. 5.5.6.3. length based in variable length packet mode, payloadlength must be programmed with the maxi mum payload length permitted. if received length byte is smaller than this maximum then th e packet is accepted and processed, otherwise it is discarded. please note that the received le ngth byte, as part of the payload, is not stri pped off the packet and is made available in the fifo. to disable this function the user should set the value of the payloadlength to 255. 5.5.6.4. crc based the crc check is enabled by setting bit crcon in regpacketconfig1 . it is used for checking the integrity of the message. the checksum is calculated on the received payload and comp ared with the two checksum bytes received. the result of the comparison is stored in bit crcok. by default, if the crc check fails then the fifo is automatically cleared and no inte rrupt is generated. this filtering functio n can be disabled via crcautoclearoff bit and in this case, even if crc fa ils, the fifo is not cleared and only payloadready interrupt goes high. please note that in both cases, the two crc checksum bytes ar e stripped off by the packet handler and only the payload is made available in the fifo. the crc is based on the ccitt polynomial as shown below. this implementation also detects errors due to leading and trailing zeros.
www.semtech.com page 50 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 figure 31. crc implementation 5.5.7. dc-free data mechanisms the received payload can be de-whitened or manchester decoded automatically in the sx1239 packet handler. note only one of the two methods should be enabled at a time. 5.5.7.1. manc hester decoding manchester decoding is enabled if dcfree = 01 and can only be used in packet mode. the manchester data is decoded to nrz code by decoding "10" as '1' and "01" as '0'. in this case, the maximum chip rate is th e maximum bit rate given in the specificatio ns section and the actual bit rate is half the chip rate. manchester decoding is only applied to the payload and crc checksum while preamble and sync word are kept nrz. however, the chip rate from preamble to crc is the same and defined by bitrate in regbitrate (chip rate = bit rate nrz = 2 x bit rate manchester). manchester decoding is thus made transparent for the user, who still re trieves nrz data from the fifo. figure 32. manchester decoding 5.5.7.2. data de-whitening another technique called whitening or scrambling is widely us ed for randomizing the user data before radio transmission. the data is whitened using a random sequence on the tx side and de-whitened on the rx side using the same sequence. comparing to manchester technique it has the advantage of ke eping nrz data rate i.e. actual bit rate is not halved. x 14 x 13 x 12 x 11 x 5 x 0 x 15 crc polynomial =x 16 + x 12 + x 5 + 1 * * * x 4 * * * data input ...sync payload... rf chips @ br ... 1 1 1 0 1 0 0 1 0 0 1 0 1 1 0 1 0 ... user/nrz bits manchester off ... 1 1 1 0 1 0 0 1 0 0 1 0 1 1 0 1 0 ... user/nrz bits manchester on ... 1 1 1 0 1 0 0 1 0 0 1 1 ... t 1/br 1/br
www.semtech.com page 51 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 the de-whitening process is enabled if dcfree = 10 . the data, including payload and 2-byte crc checksum, is de- whitened by xoring it with a random sequence generated in a 9-bit lfsr, shown in figure 33. payload de-whitening is thus made transparent for the user, who still re trieves nrz data from the fifo. figure 33. data de-whitening received data de-whitened data
www.semtech.com page 52 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 6. configuration and status registers 6.1. general description table 19 registers summary address register name reset (built-in) default (recom mended) description 0x00 regfifo 0x00 fifo read/write access 0x01 regopmode 0x04 operating modes of the receiver 0x02 regdatamodul 0x00 data operation mode and modulation settings 0x03 regbitratemsb 0x1a bit rate setting, most significant bits 0x04 regbitratelsb 0x0b bit rate setting, least significant bits 0x05 reserved05 0x00 - 0x06 reserved06 0x52 - 0x07 regfrfmsb 0xe4 rf carrier frequency, most significant bits 0x08 regfrfmid 0xc0 rf carrier frequency, intermediate bits 0x09 regfrflsb 0x00 rf carrier frequency, least significant bits 0x0a regosc1 0x41 rc oscillators settings 0x0b regafcctrl 0x00 afc control in low modulation index situations 0x0c reglowbat 0x02 low battery indicator settings 0x0d reglisten1 0x92 listen mode settings 0x0e reglisten2 0xf5 listen mode idle duration 0x0f reglisten3 0x20 listen mode rx duration 0x10 regversion 0x23 semtech id relating the silicon revision 0x11 reserved11 0x9f - 0x12 reserved12 0x09 - 0x13 reserved13 0x1a - 0x14 reserved14 0x40 - 0x15 reserved15 0xb0 - 0x16 reserved16 0x7b - 0x17 reserved17 0x9b - 0x18 reglna 0x08 0x88 lna settings 0x19 regrxbw 0x86 0x55 channel filter bw control
www.semtech.com page 53 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 0x1a regafcbw 0x8a 0x8b channel filter bw control during the afc routine 0x1b regookpeak 0x40 ook demodulator selection and control in peak mode 0x1c regookavg 0x80 average threshold control of the ook demodulator 0x1d regookfix 0x06 fixed threshold control of the ook demodulator 0x1e regafcfei 0x10 afc and fei control and status 0x1f regafcmsb 0x00 msb of the frequency correction of the afc 0x20 regafclsb 0x00 lsb of the frequency correction of the afc 0x21 regfeimsb 0x00 msb of the calculated frequency error 0x22 regfeilsb 0x00 lsb of the calculated frequency error 0x23 regrssiconfig 0x02 rssi-related settings 0x24 regrssivalue 0xff rssi value in dbm 0x25 regdiomapping1 0x00 mapping of pins dio0 to dio3 0x26 regdiomapping2 0x05 0x07 mapping of pins dio4 and dio5, clkout frequency 0x27 regirqflags1 0x80 status register: pll lock state, timeout, rssi > threshold... 0x28 regirqflags2 0x00 status register: fifo handling flags, low battery detection... 0x29 regrssithresh 0xff 0xe4 rssi threshold control 0x2a regrxtimeout1 0x00 timeout duration between rx request and rssi detection 0x2b regrxtimeout2 0x00 timeout duration between rssi detection and payloadready 0x2c reserved2c 0x00 - 0x2d reserved2d 0x03 - 0x2e regsyncconfig 0x98 sync word recognition control 0x2f-0x36 regsyncvalue1-8 0x00 0x01 sync word bytes, 1 through 8 0x37 regpacketconfig1 0x10 packet mode settings 0x38 regpayloadlength 0x40 payload length setting 0x39 regnodeadrs 0x00 node address 0x3a regbroadcastadrs 0x00 broadcast address 0x3b regautomodes 0x00 auto modes settings 0x3c regfifothresh 0x0f 0x8f fifo threshold 0x3d regpacketconfig2 0x02 packet mode settings address register name reset (built-in) default (recom mended) description
www.semtech.com page 54 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 note - reset values are auto matically refreshed in the chip at power on reset - default values are the semtech recommended regi ster values, optimizing the device operation - registers for which the default value differs from the re set value are denoted by a * in the tables of section 6 0x3e-0x4d regaeskey1-16 0x00 16 bytes of the cypher key 0x4e regtemp1 0x01 temperature sensor control 0x4f regtemp2 0x00 temperature readout 0x58 regtestlna 0x1b sensitivity boost 0x6f regtestdagc 0x00 0x30 fading margin improvement 0x71 regtestafc 0x00 afc offset for low modulation index afc 0x50 + regtest - internal test registers address register name reset (built-in) default (recom mended) description
www.semtech.com page 55 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 6.2. common confi guration registers table 20 common configuration registers name (address) bits variable name mode default value description regfifo (0x00) 7-0 fifo rw 0x00 fifo data output regopmode (0x01) 7 sequenceroff rw 0 controls the automatic sequencer (see section 4.2 ): 0 ? operating mode as selected with mode bits in regopmode is automatically reached with the sequencer 1 ? mode is forced by the user 6 listenon rw 0 enables listen mode: 0 ? off (see section 4.3) 1 ? on 5 listenabort w 0 aborts listen mode when set together with listenon=0 and new mode selection in 1 spi access (see section 4.3) always reads 0. 4-2 mode rw 001 receiver?s operating modes: 000 ? sleep mode (sleep) 001 ? standby mode (stdby) 010 ? frequency synthesizer mode (fs) 100 ? receiver mode (rx) others ? reserved reads the value corresponding to the current chip mode 1-0 - r 00 unused regdatamodul (0x02) 7 - r 0 unused 6-5 datamode rw 00 data processing mode: 00 ? packet mode 01 ? reserved 10 ? continuous mode with bit synchronizer 11 ? continuous mode without bit synchronizer 4-3 modulationtype rw 00 modulation scheme: 00 ? fsk 01 ? ook 10 - 11 ? reserved 2-0 - r 000 unused regbitratemsb (0x03) 7-0 bitrate(15:8) rw 0x1a msb of bit rate (chip rate when manchester encoding is enabled) regbitratelsb (0x04) 7-0 bitrate(7:0) rw 0x0b lsb of bit rate (chip rate if manchester encoding is enabled) default value: 4.8 kb/s reserved05 (0x05) 7-0 - r 0x00 unused reserved06 (0x06) 7-0 - r 0x52 unused regfrfmsb (0x07) 7-0 frf(23:16) rw 0xe4 msb of the rf local oscillator regfrfmid (0x08) 7-0 frf(15:8) rw 0xc0 middle byte of the rf local oscillator bitrate fxosc bitrate 15 0 (,) ---------------------------------- - =
www.semtech.com page 56 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 regfrflsb (0x09) 7-0 frf(7:0) rw 0x00 lsb of the rf local oscillator default value: frf = 915 mhz (32 mhz xo) regosc1 (0x0a) 7 rccalstart w 0 triggers the calibration of the rc oscillator when set. always reads 0. rc calibration must be triggered in standby mode. 6 rccaldone r 1 0 ? rc calibration in progress 1 ? rc calibration is over 5-0 - r 000001 unused regafcctrl (0x0b) 7-6 - r 00 unused 5 afclowbetaon rw 0 improved afc routine for signals with modulation index lower than 2. refer to section 3.4.17 for details 0 ? standard afc routine 1 ? improved afc routine 4-0 - r 00000 unused reglowbat (0x0c) 7-5 - r 000 unused 4 lowbatmonitor rw - real-time (not latched) output of the low battery detector, when enabled. 3 lowbaton rw 0 low battery detector enable signal 0 ? lowbat off 1 ? lowbat on 2-0 lowbattrim rw 010 trimming of the lowbat threshold: 000 ? 1.695 v 001 ? 1.764 v 010 ? 1.835 v 011 ? 1.905 v 100 ? 1.976 v 101 ? 2.045 v 110 ? 2.116 v 111 ? 2.185 v reglisten1 (0x0d) 7-6 listenresolidle rw 10 resolution of listen modes timings (calibrated rc osc): 0101 ? 64 us 1010 ? 4.1 ms 1111 ? 262 ms others ? reserved 5-4 listenresolrx rw 01 resolution of listen mode rx time (calibrated rc osc): 00 ? reserved 01 ? 64 us 10 ? 4.1 ms 11 ? 262 ms 3 listencriteria rw 0 criteria for packet acceptance in listen mode: 0 ? signal strength is above rssithreshold 1 ? signal strength is above rssithreshold and syncaddress matched 2-1 listenend rw 01 action taken after acceptance of a packet in listen mode: 00 ? chip stays in rx mode. li sten mode stops and must be disabled (see section 4.3). 01 ? chip stays in rx mode until payloadready or timeout interrupt occurs. it then goes to the mode defined by mode . listen mode stops and must be disabled (see section 4.3). 10 ? chip stays in rx mode until payloadready or timeout interrupt occurs. listen mode then resumes in idle state. fifo content is lost at next rx wakeup. 11 ? reserved 0 - r 0 unused frf fstep frf 23 0 ; () =
www.semtech.com page 57 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 reglisten2 (0x0e) 7-0 listencoefidle rw 0xf5 duration of the idle phase in listen mode. reglisten3 (0x0f) 7-0 listencoefrx rw 0x20 duration of the rx phase in listen mode (startup time included, see section 4.2.1) regversion (0x10) 7-0 version r 0x23 version code of the chip. bits 7-4 give the full revision number; bits 3-0 give the metal mask revision number. solidle listen idle listencoef t listenidle re ? = solrx listen rx listencoef t listenrx re ? =
www.semtech.com page 58 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 6.3. receiver registers table 21 receiver registers name (address) bits variable name mode default value description reserved14 (0x14) 7-0 - r 0x40 unused reserved15 (0x15) 7-0 - r 0xb0 unused reserved16 (0x16) 7-0 - r 0x7b unused reserved17 (0x17) 7-0 - r 0x9b unused reglna (0x18) 7 lnazin rw 1 * lna?s input impedance 0 ? 50 ohms 1 ? 200 ohms 6 - r 0 unused 5-3 lnacurrentgain r 001 current lna gain, set either manually, or by the agc 2-0 lnagainselect rw 000 lna gain setting: 000 ? gain set by the internal agc loop 001 ? g1 = highest gain 010 ? g2 = highest gain ? 6 db 011 ? g3 = highest gain ? 12 db 100 ? g4 = highest gain ? 24 db 101 ? g5 = highest gain ? 36 db 110 ? g6 = highest gain ? 48 db 111 ? reserved regrxbw (0x19) 7-5 dccfreq rw 010 * cut-off frequency of the dc offset canceller (dcc): ~4% of the rxbw by default 4-3 rxbwmant rw 10 * channel filter bandwidth control: 00 ? rxbwmant = 16 10 ? rxbwmant = 24 01 ? rxbwmant = 20 11 ? reserved 2-0 rxbwexp rw 101 * channel filter bandwidth control: fsk mode: ook mode: see table 10 for tabulated values regafcbw (0x1a) 7-5 dccfreqafc rw 100 dccfreq parameter used during the afc 4-3 rxbwmantafc rw 01 rxbwmant parameter used during the afc 2-0 rxbwexpafc rw 011 * rxbwexp parameter used during the afc fc 4 rxbw 2 2 dccfreq 2 + ----------------------------------------- - = rxbw fxosc rxbwmant 2 rxbwexp 2 + ----------------------------------------------------------------- - = rxbw fxosc rxbwmant 2 rxbwexp 3 + ----------------------------------------------------------------- - =
www.semtech.com page 59 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 regookpeak (0x1b) 7-6 ookthreshtype rw 01 selects type of threshold in the ook data slicer: 00 ? fixed 10 ? average 01 ? peak 11 ? reserved 5-3 ookpeaktheshstep rw 000 size of each decrement of the rssi threshold in the ook demodulator: 000 ? 0.5 db 001 ? 1.0 db 010 ? 1.5 db 011 ? 2.0 db 100 ? 3.0 db 101 ? 4.0 db 110 ? 5.0 db 111 ? 6.0 db 2-0 ookpeakthreshdec rw 000 period of decrement of the rssi threshold in the ook demodulator: 000 ? once per chip 001 ? once every 2 chips 010 ? once every 4 chips 011 ? once every 8 chips 100 ? twice in each chip 101 ? 4 times in each chip 110 ? 8 times in each chip 111 ? 16 times in each chip regookavg (0x1c) 7-6 ookaveragethreshfilt rw 10 filter coeffi cients in average mode of the ook demodulator: 00 ? f c chip rate / 32. 01 ? f c chip rate / 8. 10 ? f c chip rate / 4. 11 ? f c chip rate / 2. 5-0 - r 000000 unused regookfix (0x1d) 7-0 ookfixedthresh rw 0110 (6db) fixed threshold value (in db) in the ook demodulator. used when ookthrestype = 00 regafcfei (0x1e) 7 - r 0 unused 6 feidone r 0 0 ? fei is on-going 1 ? fei finished 5 feistart w 0 triggers a fei measurement when set. always reads 0. 4 afcdone r 1 0 ? afc is on-going 1 ? afc has finished 3 afcautoclearon rw 0 only valid if afcautoon is set 0 ? afc register is not cleared before a new afc phase 1 ? afc register is cleared before a new afc phase 2 afcautoon rw 0 0 ? afc is performed each time afcstart is set 1 ? afc is performed each time rx mode is entered 1 afcclear w 0 clears the afcvalue if set in rx mode. always reads 0 0 afcstart w 0 triggers an afc when set. always reads 0. regafcmsb (0x1f) 7-0 afcvalue(15:8) r 0x00 msb of the afcvalue, 2?s complement format regafclsb (0x20) 7-0 afcvalue(7:0) r 0x00 lsb of the afcvalue, 2?s complement format frequency correction = afcvalue x fstep regfeimsb (0x21) 7-0 feivalue(15:8) r - msb of the measured frequency offset, 2?s complement regfeilsb (0x22) 7-0 feivalue(7:0) r - lsb of the measured frequency offset, 2?s complement frequency error = feivalue x fstep regrssiconfig (0x23) 7-2 - r 000000 unused 1 rssidone r 1 0 ? rssi is on-going 1 ? rssi sampling is finished, result available 0 rssistart w 0 trigger a rssi measurement when set. always reads 0. regrssivalue (0x24) 7-0 rssivalue r 0xff absolute value of the rssi in dbm, 0.5db steps. rssi = - rssivalue/2 [dbm]
www.semtech.com page 60 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 6.4. irq and pin mapping registers table 22 irq and pin mapping registers name (address) bits variable name mode default value description regdiomapping1 (0x25) 7-6 dio0mapping rw 00 mapping of pins dio0 to dio5 see table 17 for mapping in continuous mode see table 18 for mapping in packet mode 5-4 dio1mapping rw 00 3-2 dio2mapping rw 00 1-0 dio3mapping rw 00 regdiomapping2 (0x26) 7-6 dio4mapping rw 00 5-4 dio5mapping rw 00 3 - r 0 unused 2-0 clkout rw 111 * selects clkout frequency: 000 ? fxosc 001 ? fxosc / 2 010 ? fxosc / 4 011 ? fxosc / 8 100 ? fxosc / 16 101 ? fxosc / 32 110 ? rc (automatically enabled) 111 ? off regirqflags1 (0x27) 7 modeready r 1 set when the operation mode requested in mode , is ready - sleep: enteri ng sleep mode - standby: xo is running - fs: pll is locked - rx: rssi sampling starts cleared when changing operating mode. 6 rxready r 0 set in rx mode, after rssi, agc and afc. cleared when leaving rx. 5 - r 0 unused 4 plllock r 0 set (in fs and rx) when the pll is locked. cleared when it is not. 3 rssi rwc 0 set in rx when the rssivalue exceeds rssithreshold. cleared when leaving rx. 2 timeout r 0 set when a timeout occurs (see timeoutrxstart and timeoutrssithresh ) cleared when leaving rx or fifo is emptied. 1 automode r 0 set when entering intermediate mode. cleared when exiting intermediate mode. please note that in sleep mode a small delay can be observed between automode interrupt and the corresponding enter/exit condition. 0 syncaddressmatch r/rwc 0 set when sync and address (if enabled) are detected. cleared when leaving rx or fifo is emptied. this bit is read only in packet mode, rwc in continuous mode
www.semtech.com page 61 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 regirqflags2 (0x28) 7 fifofull r 0 set when fifo is full (i.e. contains 66 bytes), else cleared. 6 fifonotempty r 0 set when fifo contains at least one byte, else cleared 5 fifolevel r 0 set when the number of bytes in the fifo strictly exceeds fifothreshold , else cleared. 4 fifooverrun rwc 0 set when fifo overrun occurs. (except in sleep mode) flag(s) and fifo are cleared when this bit is set. the fifo then becomes immediately available for the next reception. 3 - r 0 unused 2 payloadready r 0 set in rx when the payload is ready (i.e. last byte received and crc, if enabled and crcautoclearoff is cleared , is ok). cleared when fifo is empty. 1 crcok r 0 set in rx when the crc of the payload is ok. cleared when fifo is empty. 0 lowbat rwc - set when the battery voltage drops below the low battery threshold. cleared only when set by the user. regrssithresh (0x29) 7-0 rssithreshold rw 0xe4 * rssi trigger level for rssi interrupt : - rssithreshold / 2 [dbm] regrxtimeout1 (0x2a) 7-0 timeoutrxstart rw 0x00 timeout interrupt is generated timeoutrxstart *16*t bit after switching to rx mode if rssi interrupt doesn?t occur (i.e. rssivalue > rssithreshold) 0x00: timeoutrxstart is disabled regrxtimeout2 (0x2b) 7-0 timeoutrssithresh rw 0x00 timeout interrupt is generated timeoutrssithresh *16*t bit after rssi interrupt if payloadready interrupt doesn?t occur. 0x00: timeoutrssithresh is disabled
www.semtech.com page 62 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 6.5. packet engine registers table 23 packet engine registers name (address) bits variable name mode default value description reserved2c (0x2c) 7-0 - rw 0x00 unused reserved2d (0x2d) 7-0 - rw 0x03 unused regsyncconfig (0x2e) 7 syncon rw 1 enables the sync word detection: 0 ? off 1 ? on 6 fifofillcondition rw 0 fifo filling condition: 0 ? if syncaddress interrupt occurs 1 ? as long as fifofillcondition is set 5-3 syncsize rw 011 size of the sync word: ( syncsize + 1) bytes 2-0 synctol rw 000 number of tolera ted bit errors in sync word regsyncvalue1 (0x2f) 7-0 syncvalue(63:56) rw 0x01 * 1 st byte of sync word. (msb byte) used if syncon is set. regsyncvalue2 (0x30) 7-0 syncvalue(55:48) rw 0x01 * 2 nd byte of sync word used if syncon is set and (syncsize +1) >= 2. regsyncvalue3 (0x31) 7-0 syncvalue(47:40) rw 0x01 * 3 rd byte of sync word. used if syncon is set and (syncsize +1) >= 3. regsyncvalue4 (0x32) 7-0 syncvalue(39:32) rw 0x01 * 4 th byte of sync word. used if syncon is set and (syncsize +1) >= 4. regsyncvalue5 (0x33) 7-0 syncvalue(31:24) rw 0x01 * 5 th byte of sync word. used if syncon is set and (syncsize +1) >= 5. regsyncvalue6 (0x34) 7-0 syncvalue(23:16) rw 0x01 * 6 th byte of sync word. used if syncon is set and (syncsize +1) >= 6. regsyncvalue7 (0x35) 7-0 syncvalue(15:8) rw 0x01 * 7 th byte of sync word. used if syncon is set and (syncsize +1) >= 7. regsyncvalue8 (0x36) 7-0 syncvalue(7:0) rw 0x01 * 8 th byte of sync word. used if syncon is set and (syncsize +1) = 8.
www.semtech.com page 63 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 regpacketconfig1 (0x37) 7 packetformat rw 0 defines the packet format used: 0 ? fixed length 1 ? variable length 6-5 dcfree rw 00 defines dc-free decoding performed: 00 ? none (off) 01 ? manchester 10 ? whitening 11 ? reserved 4 crcon rw 1 enables crc check: 0 ? off 1 ? on 3 crcautoclearoff rw 0 defines the behavior of the packet handler when crc check fails: 0 ? clear fifo and restart new packet reception. no payloadready interrupt issued. 1 ? do not clear fifo. payloadready interrupt issued. 2-1 addressfiltering rw 00 defines address based filtering in rx: 00 ? none (off) 01 ? address field must match nodeaddress 10 ? must match nodeaddress or broadcastaddress 11 ? reserved 0 - rw 0 unused regpayloadlength (0x38) 7-0 payloadlength rw 0x40 if packetformat = 0 (fixed), payload length. if packetformat = 1 (variable), max length in rx regnodeadrs (0x39) 7-0 nodeaddress rw 0x00 node address used in address filtering. regbroadcastadrs (0x3a) 7-0 broadcastaddress rw 0x00 broadcast address used in address filtering. regautomodes (0x3b) 7-5 entercondition rw 000 interrupt condition for entering the intermediate mode: 000 ? none (automodes off) 001 ? rising edge of fifonotempty 010 ? rising edge of fifolevel 011 ? rising edge of crcok 100 ? rising edge of payloadready 101 ? rising edge of syncaddress 110 ? reserved 111 ? falling edge of fifonotempty (i.e. fifo empty) 4-2 exitcondition rw 000 interrupt condition for exiting the intermediate mode: 000 ? none (automodes off) 001 ? falling edge of fifonotempty (i.e. fifo empty) 010 ? rising edge of fifolevel or timeout 011 ? rising edge of crcok or timeout 100 ? rising edge of payloadready or timeout 101 ? rising edge of syncaddress or timeout 110 ? reserved 111 ? rising edge of timeout 1-0 intermediatemode rw 00 intermediate mode: 00 ? sleep mode (sleep) 01 ? standby mode (stdby) 10 ? receiver mode (rx) 11 ? reserved regfifothresh (0x3c) 7 - rw 1 * unused 6-0 fifothreshold rw 0001111 used to trigger fifolevel interrupt.
www.semtech.com page 64 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 regpacketconfig2 (0x3d) 7-4 interpacketrxdelay rw 0000 after payloadready occurred, defines the delay between fifo empty and the start of a new rssi phase for next packet. must match the transmi tter?s pa ramp-down time. - tdelay = 0 if interpacketrxdelay >= 12 - tdelay = (2 interpacketrxdelay ) / bitrate otherwise 3 - rw 0 unused 2 restartrx w 0 forces the receiver in wait mode, in continuous rx mode. always reads 0. 1 autorxrestarton rw 1 enables automatic rx restart (rssi phase) after payloadready occurred and packet has been completely read from fifo: 0 ? off. restartrx can be used. 1 ? on. rx auto. restart after interpacketrxdelay . 0 aeson rw 0 enable the aes decryption: 0 ? off 1 ? on (payload limited to 66 bytes maximum) regaeskey1 (0x3e) 7-0 aeskey(127:120) w 0x00 1 st byte of cipher key (msb byte) regaeskey2 (0x3f) 7-0 aeskey(119:112) w 0x00 2 nd byte of cipher key regaeskey3 (0x40) 7-0 aeskey(111:104) w 0x00 3 rd byte of cipher key regaeskey4 (0x41) 7-0 aeskey(103:96) w 0x00 4 th byte of cipher key regaeskey5 (0x42) 7-0 aeskey(95:88) w 0x00 5 th byte of cipher key regaeskey6 (0x43) 7-0 aeskey(87:80) w 0x00 6 th byte of cipher key regaeskey7 (0x44) 7-0 aeskey(79:72) w 0x00 7 th byte of cipher key regaeskey8 (0x45) 7-0 aeskey(71:64) w 0x00 8 th byte of cipher key regaeskey9 (0x46) 7-0 aeskey(63:56) w 0x00 9 th byte of cipher key regaeskey10 (0x47) 7-0 aeskey(55:48) w 0x00 10 th byte of cipher key regaeskey11 (0x48) 7-0 aeskey(47:40) w 0x00 11 th byte of cipher key regaeskey12 (0x49) 7-0 aeskey(39:32) w 0x00 12 th byte of cipher key regaeskey13 (0x4a) 7-0 aeskey(31:24) w 0x00 13 th byte of cipher key regaeskey14 (0x4b) 7-0 aeskey(23:16) w 0x00 14 th byte of cipher key regaeskey15 (0x4c) 7-0 aeskey(15:8) w 0x00 15 th byte of cipher key regaeskey16 (0x4d) 7-0 aeskey(7:0) w 0x00 16 th byte of cipher key (lsb byte)
www.semtech.com page 65 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 6.6. temperature sensor registers table 24 temperature sensor registers 6.7. test registers table 25 test registers name (address) bits variable name mode default value description regtemp1 (0x4e) 7-4 - r 0000 unused 3 tempmeasstart w 0 triggers the temperature measurement when set. always reads 0. 2 tempmeasrunning r 0 set to 1 while the temperature measurement is running. toggles back to 0 when the measurement has completed. the receiver can not be used while measuring temperature 1-0 - r 01 unused regtemp2 (0x4f) 7-0 tempvalue r - measured temperature -1c per lsb needs calibration for accuracy name (address) bits variable name mode default value description regtestlna (0x58) 7-0 sensitivityboost rw 0x1b high sensit ivity or normal sensitivity mode: 0x1b ? normal mode 0x2d ? high sensitivity mode regtestdagc (0x6f) 7-0 continuousdagc rw 0x30 * fading margin improvement, refer to 3.4.4 0x00 ? normal mode 0x10 ? improved margin, use if afclowbetaon=1 0x30 ? improved margin, use if afclowbetaon=0 regtestafc (0x71) 7-0 lowbetaafcoffset rw 0x00 afc offset set for low modulation in dex systems, used if afclowbetaon=1 . offset = lowbetaafcoffset x 488 hz
www.semtech.com page 66 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 7. application information 7.1. crystal resonator specification table 26 shows the crystal resonator sp ecification for the crystal reference oscillator circuit of the sx1239. this specification covers the full range of operation of the sx1239 and is employed in the reference design. table 26 crystal specification notes - the initial frequency tolerance, temper ature stability and ageing performance should be chosen in accordance with the target operating temperature range and the receiver bandwidth selected. - the loading capacitance should be applied externally, and adapted to the actual cload specification of the xtal. - a minimum xtal frequency of 28 mhz is required to cover the 863-870 mhz band, 29 mhz for the 902-928 mhz band 7.2. reset of the chip a power-on reset of the sx1239 is trig gered at power up. additionally, a manual reset can be issued by controlling pin 6. 7.2.1. por if the application requires the disconnectio n of vdd from the sx1239, despite of th e extremely low sleep mode current, the user should wait for 10 ms from of the end of the por cycle before commencing communications over the spi bus. pin 6 (reset) should be left floating during the por sequence. figure 34. por timing diagram please note that any clkout activity can also be used to detect that the chip is ready. symbol description conditions min typ max unit fxosc xtal frequency 26 - 32 mhz rs xtal serial resistance - 30 140 ohms c0 xtal shunt capacitance - 2.8 7 pf cload external foot capacitance on each pin xta and xtb 8 16 22 pf wait for 10 ms vdd pin 6 (output) chip is ready from this point on undefined
www.semtech.com page 67 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 7.2.2. manual reset a manual reset of the sx1239 is possible even for applicat ions in which vdd cannot be physically disconnected. pin 6 should be pulled high for a hundred microseconds, and then releas ed. the user should then wait for 5 ms before using the chip. figure 35. manual reset timing diagram note whilst pin 6 is driven high, an ov er current consumption of up to ten milliamps can be seen on vdd. 7.3. reference design please contact your semtech representative for evaluation tool s, reference designs and design assistance. note that all schematics shown in this section are fu ll schematics, listing all re quired components, including decoupling capacitors. figure 36. application schematic note in very cost-sensitive and/or size-constrained applications where it is acceptable to degrade the receiver sensitivity by approximately 2 db, l1 and c1 can be omitted. vdd > 100 us chip is ready from this point on pin 6 ( in p ut ) high-z high-z ??1?? wait for 5 ms
www.semtech.com page 68 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 8. packaging information 8.1. package outline drawing the sx1239 is available in a 24-lead qfn package as show in figure 37. figure 37. package outline drawing 8.2. recommended land pattern figure 38. recommended land pattern millimeters 0.65 bsc 0.00 a1 e1 aaa bbb n e l a2 d1 d e b 0.35 4.90 4.90 3.20 - 0.25 dim a dimensions 0.80 min - 0.05 5.10 5.10 3.30 0.45 0.35 0.40 0.10 0.08 24 5.00 (0.20) 3.25 5.00 0.30 - 1.00 max - nom b aaa c 3.20 3.25 3.30 d e a a2 a1 e/2 e bxn lxn e/2 d/2 d1 e1 c seating plane 1 2 n bbb c a b coplanarity applies to the exposed pad as well as the terminals. controlling dimensions are in millimeters (angles in degrees). notes: 2. 1. a pin 1 indicator (laser mark) k h g z (c) y p x this land pattern is for reference purposes only. consult your manufacturing group to ensure your notes: 2. dim x y h k p c g millimeters (4.90) 0.35 0.80 3.30 0.65 3.30 4.10 dimensions company's manufacturing guidelines are met. 5.70 z failure to do so may compromise the thermal and/or functional performance of the device. shall be connected to a system ground plane. thermal vias in the land pattern of the exposed pad 3. 4. square package-dimensions apply in both x and y directions. controlling dimensions are in millimeters (angles in degrees). 1.
www.semtech.com page 69 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 8.3. thermal impedance the thermal impedance of this package is: theta ja = 23.8 c/w typ. , calculated from a package in still air, on a 4-layer fr4 pcb, as per the jedec standard. 8.4. tape & reel specification figure 39. tape & reel specification note single sprocket holes
www.semtech.com page 70 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 9. chip revisions three distinct chip populations exis t and can be identified as follows: table 27 chip identification this document describes the behavior and characteristics of the sx1239 v2c. minor differences can be observed between the three versions, and they are lis ted in the following sub sections. 9.1. rc oscill ator calibration on the sx1239 v2a, rc calibration at power-up needs to be performed according to the following routine: this is not required in the version v2b any more, where the calibration is fully automatic. 9.2. listen mode 9.2.1. resolutions on the sx1239 v2a, the listen mode resolutions were identi cal for the idle phase and the rx phase. they are now independently conf igurable, adding flexibility in the setup of th e listen mode. figure 40. listen mode resolutions, v2a figure 41. listen mode resolution, v2b chip version register value @ address 0x10 lot codes (see figure 3) comment v2a 0x21 w0k976.00 limited supply v2b 0x22 w6a114.0a | w0n382.00 w0n386.00 | w0p051.00 limited supply v2c 0x23 w0s934.01 and all others running production /////// rc calibration (once at por) /////// setrfmode(rf_standby); writeregister(0x57, 0x80); writeregister(reg_osc1, readregister(reg_osc1) | 0x80); while (readregister(reg_osc1) & 0x40 == 0x00); writeregister(reg_osc1, readregister(reg_osc1) | 0x80); while (readregister(reg_osc1) & 0x40 == 0x00); writeregister(0x57, 0x00); ////////////////////////////////////////////
www.semtech.com page 71 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 9.2.2. exiting listen mode in the sx1239 v2a, the following procedure was requested to exit listen mode: figure 42. exiting listen mode in sx1239 v2a listen mode can simply be exited on the sx1239 v2b by resetting bit listenon to 0 in reglisten . 9.3. ook floor thre shold default setting the following default va lue modification was requ ired on the v2a silicon: figure 43. regtestook description it is not required to modify this register any more on the sx1239 v2b. 9.4. afc control the following differences are observed between silic on revisions v2a and v2b: 9.4.1. afcautoclearon on the sx1239 v2a, it is required to manually clear afcvalue in regafcfei , when the device is in rx mode. afcautoclear function is fully func tional on the silicon version v2b. 9.4.2. afclowbetaon and lowbetaafcoffset those two bits enable a functionality that wa s not available on the silicon version v2a. 9.5. continuousdagc this register enables a functi onnality that is only availabl e in the silicon version v2c. for all three listenend settings (i.e. even for 00 and 01) disabling listen mode can be done anytime by writing all together in a single spi write command (same register) : ? listenon to 0 ? listenabort to 1 mode to the wanted operation mode
www.semtech.com page 72 sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011 10. revision history table 28 revision history revision date comment 1 feb 2010 first final datasheet version 2 april 2010 update diox mapping tables simplify and clarify the description of the agc add temperature sensor?s approximate measurement time optimize suggested frequency hopping sequences, section 4.2.5 modify listen mode resolution description list in section 9 the differences between chip versions v2a and v2b describe handling method for packets larger than the fifo size document afc for low modulation index, timing diagrams, adjust tana document regtestafc at address 0x71 add section describing setup for low modulation index systems add application schematics 3jan 2011 adjust thermal impedance value add description for the continuous-time dagc update section 9 to reflect improvements of the chip v2c
www.semtech.com page 73 semtech corporation advanced communication and sensing products division 200 flynn road, ca marillo, ca 93012 phone: (805) 498-2111 fax: (805) 498-3804 e-mail: sales@semtech.com acsupport@semtech.com internet: http://www.semtech.com contact information ? semtech 2010 a ll rights reserved. reproduction in whole or in part is prohib ited without the prior written consent of the copyright owner. th e information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. no liability will be accepted by the publisher for any consequence of its use. publication thereof does not convey nor imply any license under patent or ot her industrial or intellectual property rights. semtech assumes no responsibility or liability whatsoever for any failure or unexpected operation resulting from misuse, neglect improper installation, repair or improper handling or unusual physical or electrical stress including, but not limited to, exposure to parameters beyond the specified maximum ratings or operation outside the specified range. semtech products are not designed, intended, auth orized or warranted to be suitable for use in life-support applications, devices or systems or other critical applications. inclusion of semtech products in such applications is understood to be undertaken solely at the customer?s own risk. should a customer purchase or use semtech product s for any such unauthorized application, the customer shall indemnify and hold semtech and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs damages and attorney fees which could arise. sx1239 advanced communica tions & sensing datasheet rev 3 - jan 2011

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