Semtech LR1121 User manual

LR1121 Transceiver
User Manual
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LR1121
User Manual Rev 1.1
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Disclaimer
Long Range-Frequency Hopping Spread Spectrum (LR-FHSS) is a high link-budget, high-performance
technology combining the benefits of a modulation employing low energy per bit and advanced frequency
hopping schemes to achieve improved coexistence, spectral efficiency and sensitivity. Semtech Corp. holds
patents directed to aspects of the LR-FHSS technology.
Your use of LR-FHSS software made available by Semtech Corp. or its affiliates does not grant any rights to
their patents for LR-FHSS technology. Rights under Semtech patents may be available via various
mechanisms, including by purchasing Semtech SX1261, SX1262, SX1268, LR1110, LR1120 or LR1121
semiconductor devices, or their authorized counterparts from Semtech or its affiliates, or their respective
licensees.

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Table of Contents
1. Introduction.................................................................................................................................................... 12
1.1 Scope ................................................................................................................................................... 12
1.2 Overview ............................................................................................................................................. 12
2. System Processes.......................................................................................................................................... 13
2.1 System Modes ................................................................................................................................... 13
2.1.1 Boot.......................................................................................................................................... 14
2.1.2 Standby................................................................................................................................... 14
2.1.3 Calibrations............................................................................................................................ 15
2.1.4 Power Down.......................................................................................................................... 16
2.1.5 Sleep......................................................................................................................................... 17
2.1.6 Reset ........................................................................................................................................ 18
2.1.7 RX Mode.................................................................................................................................. 19
2.1.8 TX Mode.................................................................................................................................. 19
2.1.9 FS Mode .................................................................................................................................. 20
2.2 Startup Sequence ............................................................................................................................ 20
2.3 Firmware Upgrade .......................................................................................................................... 21
2.3.1 GetVersion ............................................................................................................................. 21
2.3.2 EraseFlash............................................................................................................................... 21
2.3.3 WriteFlashEncrypted.......................................................................................................... 22
2.4 Mode Transitions & Timings ........................................................................................................ 22
2.5 Info Page ............................................................................................................................................. 23
2.5.1 EraseInfoPage ....................................................................................................................... 23
2.5.2 WriteInfoPage....................................................................................................................... 23
2.5.3 ReadInfoPage........................................................................................................................ 24
3. Host-Controller Interface ........................................................................................................................... 25
3.1 Write Commands ............................................................................................................................. 25
3.2 Read Commands .............................................................................................................................. 25
3.3 Command Endianness ................................................................................................................... 26
3.4 Status Registers ................................................................................................................................ 27
3.4.1 GetStatus................................................................................................................................ 27
3.4.2 Stat1 ......................................................................................................................................... 27
3.4.3 Stat2 ........................................................................................................................................ 28
3.5 BUSY ..................................................................................................................................................... 29
3.6 Errors .................................................................................................................................................... 30
3.6.1 GetErrors................................................................................................................................. 30
3.6.2 ClearErrors.............................................................................................................................. 30
3.7 Memory Access ................................................................................................................................ 31
3.7.1 WriteRegMem32.................................................................................................................. 31
3.7.2 ReadRegMem32................................................................................................................... 31
3.7.3 WriteRegMemMask32 ....................................................................................................... 32
3.7.4 WriteBuffer8 .......................................................................................................................... 32
3.7.5 ReadBuffer8........................................................................................................................... 33
3.7.6 ClearRxBuffer ........................................................................................................................ 33
3.7.7 GetRandomNumber........................................................................................................... 33

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3.7.8 EnableSpiCrc ......................................................................................................................... 34
4. GPIOs................................................................................................................................................................. 35
4.1 Interrupts ............................................................................................................................................ 35
4.1.1 SetDioIrqParams.................................................................................................................. 37
4.1.2 ClearIrq.................................................................................................................................... 37
4.2 RF Switch Control ............................................................................................................................ 38
4.2.1 SetDioAsRfSwitch................................................................................................................ 38
4.2.2 DriveDiosInSleepMode ..................................................................................................... 39
4.3 Temperature Sensor ....................................................................................................................... 40
4.3.1 GetTemp................................................................................................................................. 40
5. Power Distribution....................................................................................................................................... 41
5.1 Power Modes .................................................................................................................................... 41
5.1.1 SetRegMode.......................................................................................................................... 41
5.2 VBAT Measurement ........................................................................................................................ 42
5.2.1 GetVbat ................................................................................................................................... 42
5.3 Power-On-Reset and Brown-Out-Reset ................................................................................... 43
5.4 Low Battery Detector ..................................................................................................................... 43
5.5 Over Current Protection ................................................................................................................ 43
6. Clock Sources ................................................................................................................................................. 44
6.1 RC Oscillators Clock References ................................................................................................. 44
6.2 High-Precision Clock References ............................................................................................... 44
6.2.1 32.768kHz Crystal ............................................................................................................... 44
6.2.2 32MHz Crystal....................................................................................................................... 44
6.2.3 32MHz TCXO ......................................................................................................................... 45
6.3 Commands ......................................................................................................................................... 46
6.3.1 ConfigLfClock........................................................................................................................ 46
6.3.2 SetTcxoMode........................................................................................................................ 47
7. Radio.................................................................................................................................................................. 48
7.1 Overview ............................................................................................................................................. 48
7.2 Commands ......................................................................................................................................... 49
7.2.1 SetRfFrequency.................................................................................................................... 49
7.2.2 SetRx ........................................................................................................................................ 49
7.2.3 SetTx......................................................................................................................................... 50
7.2.4 AutoTxRx ................................................................................................................................ 51
7.2.5 SetRxTxFallbackMode ....................................................................................................... 52
7.2.6 SetRxDutyCycle.................................................................................................................... 53
7.2.7 StopTimeoutOnPreamble ............................................................................................... 55
7.2.8 GetRssiInst.............................................................................................................................. 55
7.2.9 GetStats................................................................................................................................... 56
7.2.10 ResetStats ............................................................................................................................ 56
7.2.11 GetRxBufferStatus............................................................................................................. 57
7.2.12 SetRxBoosted ..................................................................................................................... 57
7.2.13 SetLoRaSyncWord ............................................................................................................ 58
7.2.14 GetLoRaRxHeaderInfos................................................................................................... 58
7.2.15 SetRssiCalibration............................................................................................................. 59
8. Modems ........................................................................................................................................................... 62

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8.1 Modem Configuration ................................................................................................................... 62
8.1.1 SetPacketType ..................................................................................................................... 63
8.1.2 GetPacketType ..................................................................................................................... 63
8.2 LoRa® Modem ................................................................................................................................... 64
8.2.1 LoRa Modulation Principle............................................................................................... 64
8.2.2 LoRa Packet Format............................................................................................................ 65
8.2.3 Channel Activity Detection (CAD)................................................................................. 66
8.3 LoRa® Commands ............................................................................................................................ 67
8.3.1 SetModulationParams....................................................................................................... 67
8.3.2 SetPacketParams ................................................................................................................. 68
8.3.3 SetCad ..................................................................................................................................... 68
8.3.4 SetCadParams....................................................................................................................... 69
8.3.5 SetLoRaSynchTimeout ...................................................................................................... 69
8.3.6 SetLoRaPublicNetwork...................................................................................................... 70
8.3.7 GetPacketStatus................................................................................................................... 70
8.4 (G)FSK Modem .................................................................................................................................. 71
8.4.1 (G)FSK Modulation Principle ........................................................................................... 71
8.4.2 (G)FSK Packet Engine ......................................................................................................... 71
8.4.3 (G)FSK Packet Format......................................................................................................... 72
8.4.4 SX128x Compatibility......................................................................................................... 73
8.5 (G)FSK Commands .......................................................................................................................... 74
8.5.1 SetModulationParams....................................................................................................... 74
8.5.2 SetPacketParams ................................................................................................................. 75
8.5.3 SetGfskSyncWord................................................................................................................ 76
8.5.4 SetPacketAdrs....................................................................................................................... 76
8.5.5 SetGfskCrcParams ............................................................................................................... 77
8.5.6 SetGfskWhitParams ............................................................................................................ 77
8.5.7 GetPacketStatus................................................................................................................... 78
8.6 LR-FHSS Modulation ....................................................................................................................... 79
8.6.1 LR-FHSS Modulation Principle........................................................................................ 79
8.7 LR-FHSS Commands ....................................................................................................................... 80
8.7.1 SetModulationParams....................................................................................................... 80
8.7.2 LrFhssBuildFrame................................................................................................................ 80
8.7.3 LrFhssSetSyncWord............................................................................................................ 82
8.7.4 Circuit Configuration for Long Range FHSS Transmission................................... 82
8.8 Data Buffer ......................................................................................................................................... 83
8.9 RSSI Functionality ............................................................................................................................ 83
9. Power Amplifiers........................................................................................................................................... 84
9.1 PA Supply Scheme .......................................................................................................................... 85
9.1.1 Low Power PA....................................................................................................................... 86
9.1.2 High Power PA...................................................................................................................... 87
9.2 PA Output Power ............................................................................................................................. 88
9.2.1 Low Power PA....................................................................................................................... 88
9.2.2 High Power PA...................................................................................................................... 89
9.2.3 High Frequency PA ............................................................................................................. 90
9.3 PA Current Consumption ............................................................................................................. 91

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9.3.1 Low Power PA....................................................................................................................... 91
9.3.2 High Power PA...................................................................................................................... 92
9.3.3 High Frequency PA ............................................................................................................. 94
9.4 Impedance Matching Networks ................................................................................................. 95
9.4.1 Multi-Band Operation........................................................................................................ 95
9.4.2 RF Switch Implementation............................................................................................... 97
9.4.3 Direct-Tie Implementation .............................................................................................. 98
9.5 Commands ......................................................................................................................................... 99
9.5.1 SetPaConfig........................................................................................................................... 99
9.5.2 SetTxParams........................................................................................................................100
10. Cryptographic Engine ............................................................................................................................101
10.1 Description ....................................................................................................................................101
10.2 Cryptographic Keys Definition ...............................................................................................101
10.3 Commands ....................................................................................................................................103
10.3.1 CEStatus..............................................................................................................................103
10.3.2 CryptoSetKey....................................................................................................................103
10.3.3 CryptoDeriveKey.............................................................................................................104
10.3.4 CryptoProcessJoinAccept............................................................................................105
10.3.5 CryptoComputeAesCmac............................................................................................106
10.3.6 CryptoVerifyAesCmac ...................................................................................................107
10.3.7 CryptoAesEncrypt01......................................................................................................108
10.3.8 CryptoAesEncrypt...........................................................................................................109
10.3.9 CryptoAesDecrypt ..........................................................................................................110
10.3.10 CryptoStoreToFlash.....................................................................................................111
10.3.11 CryptoRestoreFromFlash...........................................................................................111
10.3.12 CryptoSetParam............................................................................................................112
10.3.13 CryptoGetParam...........................................................................................................112
11. LR1121 Provisioning................................................................................................................................113
11.1 Description ....................................................................................................................................113
11.2 Provisioning Commands ..........................................................................................................113
11.2.1 GetChipEui.........................................................................................................................113
11.2.2 GetSemtechJoinEui........................................................................................................114
11.2.3 DeriveRootKeysAndGetPin .........................................................................................115
11.3 Crypto Engine Use With LoRaWAN V1.1.x ..........................................................................117
11.4 Crypto Engine Use with LoRaWAN V1.0.x ..........................................................................118
12. Test Commands........................................................................................................................................119
12.1 Regulatory Overview .................................................................................................................119
12.1.1 ETSI.......................................................................................................................................119
12.1.2 FCC .......................................................................................................................................119
12.2 Commands ....................................................................................................................................120
12.2.1 SetTxCw..............................................................................................................................120
12.2.2 SetTxInfinitePreamble...................................................................................................120
13. List Of Commands....................................................................................................................................121
13.1 Register / Memory Access Operations ................................................................................121
13.2 System Configuration / Status Operations ........................................................................122
13.3 Radio Configuration / Status Operations ...........................................................................123

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13.4 CryptoElement Configuration / Status Operations ........................................................125
13.5 Bootloader Commands .............................................................................................................126
14. Revision History ........................................................................................................................................127

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List of Figures
Figure 1-1: LR1121 Block Diagram ............................................................................................................. 12
Figure 2-1: LR1121 Modes and Transitions ............................................................................................. 13
Figure 2-2: Bootloader.................................................................................................................................... 14
Figure 3-1: Write Command Timing Diagram........................................................................................ 25
Figure 3-2: Read Command Timing Diagram ........................................................................................ 25
Figure 3-3: GetVersion Write Capture....................................................................................................... 26
Figure 3-4: GetVersion Read Capture........................................................................................................ 26
Figure 3-5: BUSY Timing Diagram.............................................................................................................. 29
Figure 5-1: LR1121 POR and BRN Functions........................................................................................... 43
Figure 6-1: LR1121 Thermal Insulation on PCB Top Layer................................................................. 45
Figure 6-2: TCXO Circuit Diagram .............................................................................................................. 45
Figure 7-1: Radio............................................................................................................................................... 48
Figure 7-2: LR1121 Current Profile During RX Duty Cycle Operation............................................ 54
Figure 7-3: RX Duty Cycle Upon Preamble Detection......................................................................... 54
Figure 8-1: LoRa /(G)FSK / LR-FHSS Command Order......................................................................... 62
Figure 8-2: LoRa Signal Bandwidth............................................................................................................ 64
Figure 8-3: LoRa Packet Format .................................................................................................................. 65
Figure 8-4: Fixed-Length Packet................................................................................................................. 72
Figure 8-5: Variable-Length Packet............................................................................................................ 72
Figure 8-6: LR-FHSS Spectral Plot Example............................................................................................. 79
Figure 9-1: LR1121 Power Amplifiers........................................................................................................ 84
Figure 9-2: PA Block Diagram ...................................................................................................................... 85
Figure 9-3: Low Power PA VR_PA Voltage vs. TxPower ............................................................. 86
Figure 9-4: High Power PA VR_PA Voltage vs. TxPower..................................................................... 87
Figure 9-5: Low Power PA Output Power vs. TxPower ....................................................................... 88
Figure 9-6: HP PA Output Power vs. TxPower........................................................................................ 89
Figure 9-7: High Frequency PA Output Power vs. TxPower.............................................................. 90
Figure 9-8: IDDTX vs TxPower, Low Power PA, DC-DC Configuration .......................................... 91
Figure 9-9: IDDTX vs TxPower, Low Power PA, LDO Configuration............................................... 92
Figure 9-10: IDDTX vs TxPower, High Power PA, DC-DC Configuration....................................... 93
Figure 9-11: IDDTX vs TxPower, High Power PA, LDO Configuration ........................................... 93
Figure 9-12: IDDTX vs TxPower, High Frequency PA, DC-DC Configuration.............................. 94
Figure 9-13: IDDTX vs TxPower, High Frequency PA, LDO Configuration................................... 94
Figure 9-14: RF Switch, Double PA Operation ....................................................................................... 97
Figure 9-15: RF Switch, Single PA Operation (High Power PA Example)...................................... 97
Figure 9-16: Single Tie implementation: Only one PA Used (High Power PA Example)......... 98
Figure 9-17: Single Tie implementation: Both PAs Used (High Power PA Example) ............... 98
Figure 11-1: Key Derivation Scheme For LoRaWAN 1.1.x ................................................................ 117
Figure 11-2: Key Derivation Scheme for LoRaWAN 1.0.x................................................................. 118

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List of Tables
Table 2-1: SetStandby Command............................................................................................................... 14
Table 2-2: CalibImage Command............................................................................................................... 15
Table 2-3: ISM Band Values........................................................................................................................... 15
Table 2-4: Calibrate Command.................................................................................................................... 16
Table 2-5: CalibParams Parameter ............................................................................................................. 16
Table 2-6: SetSleep Command .................................................................................................................... 17
Table 2-7: SleepConfig Parameter.............................................................................................................. 17
Table 2-8: Sleep Mode Summary................................................................................................................ 17
Table 2-9: Reboot Command....................................................................................................................... 18
Table 2-10: SetFsCommand.......................................................................................................................... 20
Table 2-11: GetVersion Command............................................................................................................. 21
Table 2-12: GetVersion Response............................................................................................................... 21
Table 2-13: EraseFlash Command.............................................................................................................. 21
Table 2-14: WriteFlashEncrypted Command ......................................................................................... 22
Table 2-15: Mode Transitions and Timings............................................................................................. 22
Table 2-16: EraseInfoPage Command....................................................................................................... 23
Table 2-17: WriteInfoPage Command ...................................................................................................... 23
Table 2-18: ReadInfoPage Command ....................................................................................................... 24
Table 2-19: ReadInfoPage Response......................................................................................................... 24
Table 3-1: GetStatus Command.................................................................................................................. 27
Table 3-2: Stat1 Values ................................................................................................................................... 27
Table 3-3: Stat2 Values ................................................................................................................................... 28
Table 3-4: GetErrors Command................................................................................................................... 30
Table 3-5: GetErrors Response..................................................................................................................... 30
Table 3-6: ClearErrors Command................................................................................................................ 30
Table 3-7: WriteRegMem32 Command.................................................................................................... 31
Table 3-8: ReadRegMem32 Command..................................................................................................... 31
Table 3-9: ReadRegMem32 Response ...................................................................................................... 31
Table 3-10: WriteRegMemMask32 Command ....................................................................................... 32
Table 3-11: WriteBuffer8 Command.......................................................................................................... 32
Table 3-12: ReadBuffer8 Command........................................................................................................... 33
Table 3-13: ReadBuffer8 Response ............................................................................................................ 33
Table 3-14: ClearRxBuffer Command........................................................................................................ 33
Table 3-15: GetRandomNumber Command .......................................................................................... 33
Table 3-16: GetRandomNumber Response ............................................................................................ 33
Table 3-17: EnableSpiCrc Command......................................................................................................... 34
Table 4-1: Digital I/Os...................................................................................................................................... 35
Table 4-2: IrqToEnable Interruption Mapping....................................................................................... 36
Table 4-3: SetDioIrqParams Command.................................................................................................... 37
Table 4-4: ClearIrq Command...................................................................................................................... 37
Table 4-5: SetDioAsRfSwitch Command.................................................................................................. 38
Table 4-6: DriveDiosInSleepMode Command ....................................................................................... 39
Table 4-7: GetTemp Command................................................................................................................... 40
Table 4-8: GetTemp Response..................................................................................................................... 40
Table 5-1: SetRegMode Command............................................................................................................ 41
Table 5-2: Power Regulation Options ....................................................................................................... 41
Table 5-3: GetVbat Command ..................................................................................................................... 42
Table 5-4: GetVbat Response....................................................................................................................... 42
Table 6-1: ConfigLfClock Command.......................................................................................................... 46

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Table 6-2: SetTcxoMode Command.......................................................................................................... 47
Table 6-3: TCXO Supply Voltage Programming Values...................................................................... 47
Table 7-1: SetRfFrequency Command...................................................................................................... 49
Table 7-2: SetRx Command .......................................................................................................................... 49
Table 7-3: SetTx Command........................................................................................................................... 50
Table 7-4: AutoTxRx Command .................................................................................................................. 51
Table 7-5: SetRxTxFallbackMode Command.......................................................................................... 52
Table 7-6: SetRxDutyCycle Command...................................................................................................... 53
Table 7-7: StopTimeoutOnPreamble Command.................................................................................. 55
Table 7-8: GetRssiInst Command................................................................................................................ 55
Table 7-9: GetRssiInst Response.................................................................................................................. 55
Table 7-10: GetStats Command .................................................................................................................. 56
Table 7-11: GetStats Response.................................................................................................................... 56
Table 7-12: ResetStats Command .............................................................................................................. 56
Table 7-13: GetRxBufferStatus Command............................................................................................... 57
Table 7-14: GetRxBufferStatus Response................................................................................................. 57
Table 7-15: SetRxBoosted Command ....................................................................................................... 57
Table 7-16: SetLoRaSyncWord Command .............................................................................................. 58
Table 7-17: GetLoRaRxHeaderInfos Command..................................................................................... 58
Table 7-18: GetLoRaRxHeaderInfos Response....................................................................................... 58
Table 7-19: SetRssiCalibration Command ............................................................................................... 59
Table 7-20: Gain Tune Values....................................................................................................................... 59
Table 7-21: Recommended Values for Reference EVK........................................................................ 59
Table 8-1: SetPacketType Command........................................................................................................ 63
Table 8-2: GetPacketType Command ....................................................................................................... 63
Table 8-3: GetPacketType Response ......................................................................................................... 63
Table 8-4: SetModulationParams Command......................................................................................... 67
Table 8-5: SetPacketParams Command ................................................................................................... 68
Table 8-6: SetCad Command ....................................................................................................................... 68
Table 8-7: SetCadParams Command......................................................................................................... 69
Table 8-8: CadExitMode Parameter ........................................................................................................... 69
Table 8-9: SetLoRaSynchTimeout Command ........................................................................................ 69
Table 8-10: SetLoRaPublicNetwork Command ..................................................................................... 70
Table 8-11: GetPacketStatus Command .................................................................................................. 70
Table 8-12: GetPacketStatus Response.................................................................................................... 70
Table 8-13: SetModulationParams Command....................................................................................... 74
Table 8-14: Bandwidth Parameter.............................................................................................................. 74
Table 8-15: SetPacketParams Command................................................................................................. 75
Table 8-16: SetGfskSyncWord Command................................................................................................ 76
Table 8-17: SetPacketAdrs Command ...................................................................................................... 76
Table 8-18: SetGfskCrcParams Command............................................................................................... 77
Table 8-19: SetGfskWhitParams Command............................................................................................ 77
Table 8-20: GetPacketStatus Command .................................................................................................. 78
Table 8-21: GetPacketStatus Response.................................................................................................... 78
Table 8-22: SetModulationParams Command....................................................................................... 80
Table 8-23: LrFhssBuildFrame Command ............................................................................................... 80
Table 8-24: Maximum user payload length, in bytes .......................................................................... 81
Table 8-25: LrFhssSetSyncWord Command............................................................................................ 82
Table 8-26: RSSI Information Origin and Meaning............................................................................... 83
Table 9-1: Optimized Settings for LP PA with the Same Matching Network.............................. 95
Table 9-2: Optimized Settings for HP PA with the Same Matching Network............................. 95
Table 9-3: Optimized Settings for HF PA with the Same Matching Network ............................. 95
Table 9-4: SetPaConfig Command............................................................................................................. 99
Table 9-5: DutyCycle Parameters................................................................................................................ 99