SX1280IMLTRT

SX1280/SX1281 Long Range, Low Power, 2.4 GHz Transceiver with Ranging Capability Analog Front End & Data Conversion LORA Modem & Ranging ADC LNA Protocol Engine FLRC Modem Match PA SPI or UART PLL FSK Modem OSC DC-DC Data Buffer LDO Figure A: Transceiver Block Diagram General Description Key Features The SX1280/1 transceiver family provides ultra long range communication in the 2.4 GHz band with the linearity to withstand heavy interference. This makes them the ideal solution for robust and reliable wireless solutions. They are the first ISM band transceiver IC of their kind to integrate a time-of-flight functionality, opening up application solutions to track and localize assets in logistic chains and people for safety. These long range 2.4 GHz products include multiple physical layers and modulations to optimize long range communication at high data rate for video and security applications. Very small products for wearables can easily be designed thanks to the high level of integration and the ultra-low current consumption which allows the use of miniaturized batteries. The radio is fully compliant with all worldwide 2.4 GHz radio regulations including EN 300 440, FCC CFR 47 Part 15 and the Japanese ARIB STD-T66. The level of integration, low consumption and ranging functions within the long range 2.4 GHz product line enable enhanced connectivity and provide additional functionality to a new generation of previously unconnected devices and applications. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP • Long Range 2.4 GHz transceiver • High sensitivity, down to -132 dBm • +12.5 dBm, high efficiency PA • Low energy consumption, on-chip DC-DC • LoRa®, FLRC, (G)FSK supported modulations • Programmable bit rate • Excellent blocking immunity • Standard & Advanced Ranging Engine, Time-of-Flight • BLE PHY layer compatibility • Low system cost Applications • Home automation & appliances • IIoT Asset Management and Safety • Logistics Tracking applications • Sports /Fitness sensors and smart watches • Radio-controlled toys & drones • Agriculture • Healthcare www.semtech.com Rev 3.2 March 2020 1 of 158 Semtech Ordering Information Part Number Delivery Order Quantity SX1280IMLTRT Tape & Reel 3’000 pieces SX1281IMLTRT Tape & Reel 3’000 pieces QFN 24 Package, with the temperature operating range from -40 to 85°C Pb-free, Halogen free, RoHS/WEEE compliant product Revision History Version ECO Date Rev 1.0 035543 February 2017 Changes and/or Modifications First Release Added table of effective data rates for the LoRa® Modem Correction of the formulas for time-on-air in LoRa® Rev 1.1 037029 May 2017 Correction of typos in the chapter Host Controller Interface Update of the application schematic with optional TCXO Update of the reference design BOM Deletion of redundant information in the chapter Thermal Impedance The maximum SPI clock speed is reduced to 18 MHz Addition of a note in chapter 6.2.3 "Bandwidth" on SF and BW to be known in advance Addition of chapter 6.2.6 "Frequency Error" Addition of calculations of time-on-air in chapter 7.5 "LoRa Ranging Engine Packet" Rev 2.0 040575 February 2018 Addition of examples of SPI communication in chapter 11 "Host Controller Interface" Update of explanation on SetAutoTx in chapter 13.2.4 "BLE Specific Functions" Update of ranging results description in chapter 13.5 "Ranging Operation" Addition of an explanation of the Reference Design in chapter 14.1 "Reference Design" Addition of the tape and reel specifications in chapter 15 "Packaging Information" Addition of LoRa® and Bluetooth® trademark information Maximum RF input power (ML) is now 0 dBm Phase noise at 2.45 GHz with 1 MHz offset (PHN) is now -115 dBc/Hz Correction of minor typographical errors in tables 6-5, 6-7, 13-20 and in chapter 7.2 Rev 2.1 041639 April 2018 Addition of formulas for ranging duration in chapter 7.5.4 Addition of description of RSSI packet for LoRa® when SNR ≤ 0 in table 11-64 Correction of package thickness to 0.9 mm in chapter 15.1 Addition of package marking in chapter 15.2 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 2 of 158 Semtech Version ECO Date Changes and/or Modifications (Continued) The following specifications have been changed: • The 3rd order input intercept for maximum low power gain setting (IIP3) - at 6 MHz offset, has been changed from -6 dBm to -12 dBm - at 10 and 20 MHz offset, has been improved from -6 dBm to 0 dBm • IDDSTDBYRC has been improved from 760 μA to 700 μA • IDDSTDBYXOSC has been improved from 1.2 mA to 1 mA • PHN 10 MHz has been improved from -133 dBc/Hz to -135 dBc/Hz • TS_OS has been improved from 100 μs to 40 μs • RFSHS_L , SF7, BW = 1625 kHz, has been changed from -109 dBm to -108 dBm Rev 2.2 041738 May 2018 The switching times have been modified for the following transitions: • SLEEP to STDBY_RC from 1700 μs to 1200 μs • SLEEP to STDBY_RC from 250 μs to 130 μs • STDBY_RC to STDBY_XOSC from 53 μs to 40 μs • STDBY_RC to FS from 83 μs to 55 μs • STDBY_RC to Rx from 115 μs to 85 μs • STDBY_RC to Tx from 102 μs to 80 μs • STDBY_XOSC to FS from 40 μs to 54 μs Table 6-2 now gives the raw data rates when using LoRa® Formulas of time-on-air for long interleaving in LoRa® mode have been updated in chapter 7.4.4 SX1282 Added to the product family together with descriptions of its Advanced Ranging functionality. Improved description and detail of register retention in the Sleep Mode description of Section 11.5 FSK Mode enhanced Synch word description and graphics in Section 7 and Section 11, Tx mode now described in full. Rev 3.0 047476 July 2019 Internal Release Reference to long interleaving removed from ranging section. Detailed description of SPI bus sharing without false detection as UART interface. Correction of maximum FLRC Bandwidth to 1.2 MHz. Correction of FLRC sensitivity specification to 1.2 MHz value. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 3 of 158 Semtech Version ECO Date Changes and/or Modifications (Continued) Added table of device registers. Change of VBAT_IO tolerance down to 1.7 V. VOL and VOH Specification update with VBAT_IO = 1.7 V. RTC Calibration process documented. Description of Ranging RSSI added. Image frequency added. FEI Resolution table and description added. Correction of FLRC time on air formulae. Rev 3.1 048727 Internal Release September 2019 Correction of LoRa time on air formulae. Performance counter test mode removed. Correction of coding rate in long interleaving mode. Typographical corrections. LoRa modem frequency error tolerance reduced. UART Speed change functionality documented. SNR Usage clarified. BER Specification for FSK Updated FLRC IRQ modification Text and typographical corrections. Integration of SX1282 functionality into SX1280. Additional registers added to the register map. Rev 3.2 051322 March 2020 TCXO Output voltage added. FLRC CRC length correction. Description on high traffic, continuous mode issue. Description of FLRC elevated PER for certain Synch Word settings. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 4 of 158 Semtech Table of Contents General Description.............................................................................................................................................1 Key Features...........................................................................................................................................................1 Applications ...........................................................................................................................................................1 Ordering Information .........................................................................................................................................2 Revision History ....................................................................................................................................................2 List of Figures ..................................................................................................................................................... 10 List of Tables ...................................................................................................................................................... 11 1. Introduction.................................................................................................................................................... 15 1.1 Analog Front End ............................................................................................................................. 15 1.2 Power Distribution .......................................................................................................................... 15 1.3 Modem ................................................................................................................................................ 15 1.4 Packet Processing ............................................................................................................................ 16 1.5 Digital Interface and Control ....................................................................................................... 16 2. Pin Connections ............................................................................................................................................ 17 2.1 Transceiver Pinout ........................................................................................................................... 17 2.2 Package view ..................................................................................................................................... 18 3. Specifications ................................................................................................................................................. 19 3.1 ESD Notice .......................................................................................................................................... 19 3.2 Absolute Minimum and Maximum Ratings ........................................................................... 19 3.3 Operating Range .............................................................................................................................. 19 3.4 General Electrical Specifications ................................................................................................ 20 3.5 Receiver Electrical Specifications ............................................................................................... 21 3.5.1 Receiver Specifications...................................................................................................... 21 3.5.2 LoRa® Modem ...................................................................................................................... 22 3.5.3 FLRC Modem......................................................................................................................... 24 3.5.4 FSK Modem............................................................................................................................ 25 3.6 Transmitter Electrical Specifications ......................................................................................... 26 3.7 Crystal Oscillator Specifications ................................................................................................. 26 3.8 Digital Pin Levels .............................................................................................................................. 27 4. Analog Front End.......................................................................................................................................... 28 4.1 Transmitter ......................................................................................................................................... 28 4.2 Receiver ............................................................................................................................................... 29 4.2.1 Low Power Mode and High Sensitivity Mode........................................................... 30 4.2.2 Image Frequency................................................................................................................. 30 4.2.3 Wi-Fi and Bluetooth Immunity ....................................................................................... 30 4.3 PLL ......................................................................................................................................................... 30 4.4 RC Oscillators .................................................................................................................................... 31 5. Power Distribution ....................................................................................................................................... 32 5.1 Selecting DC-DC Converter or LDO Regulation ................................................................... 32 5.2 Flexible DIO Supply ........................................................................................................................ 33 6. Digital Baseband........................................................................................................................................... 34 6.1 Overview ............................................................................................................................................. 34 6.2 LoRa® Modem ................................................................................................................................... 35 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 5 of 158 Semtech 6.2.1 LoRa® Modulation ............................................................................................................... 35 6.2.2 Spreading Factor ................................................................................................................. 35 6.2.3 Bandwidth.............................................................................................................................. 36 6.2.4 Forward Error Correction Coding Rate ........................................................................ 36 6.2.5 Ranging Engine.................................................................................................................... 37 6.2.6 Advanced Ranging ............................................................................................................. 37 6.2.7 Frequency Error.................................................................................................................... 37 6.3 FLRC Modem ..................................................................................................................................... 38 6.3.1 Modem Bandwidth and Data Rates.............................................................................. 38 6.3.2 FEC Coding Rate .................................................................................................................. 39 6.3.3 Gaussian Filtering................................................................................................................ 40 6.4 FSK Modem ........................................................................................................................................ 41 6.4.1 Modem Bandwidth and Data Rates.............................................................................. 41 6.4.2 Modem Modulation Index ............................................................................................... 42 6.5 Guidance on Modem Selection .................................................................................................. 43 7. Packet Engine................................................................................................................................................. 44 7.1 GFSK Packet ....................................................................................................................................... 45 7.1.1 Fixed-length Packet Format ............................................................................................ 45 7.1.2 Variable-length Packet Format....................................................................................... 45 7.2 BLE Packet Format ........................................................................................................................... 46 7.3 FLRC Packet ....................................................................................................................................... 47 7.3.1 FLRC Packet Format............................................................................................................ 47 7.3.2 Fixed-Length Packet Format ........................................................................................... 47 7.3.3 Variable-length Packet Format....................................................................................... 48 7.3.4 FLRC Time-on-Air................................................................................................................. 48 7.4 LoRa® Packet ...................................................................................................................................... 49 7.4.1 LoRa® Packet Format.......................................................................................................... 49 7.4.2 Explicit (Variable-length) Header Mode...................................................................... 49 7.4.3 Implicit (Fixed-length) Header Mode........................................................................... 50 7.4.4 LoRa® Time-on-Air............................................................................................................... 50 7.5 LoRa® Ranging Engine Packet ..................................................................................................... 53 7.5.1 Ranging Packet Format..................................................................................................... 53 7.5.2 Ranging Master Exchange ............................................................................................... 54 7.5.3 Ranging Slave Exchange................................................................................................... 54 7.5.4 Total Exchange Duration .................................................................................................. 55 7.5.5 Measurement........................................................................................................................ 56 8. Data Buffer ...................................................................................................................................................... 57 8.1 Principle of Operation .................................................................................................................... 57 8.2 Receive Operation ........................................................................................................................... 58 8.3 Transmit Operation ......................................................................................................................... 58 8.4 Using the Data buffer ..................................................................................................................... 58 9. Digital Interface and Control .................................................................................................................... 59 9.1 BUSY Pin Communication ............................................................................................................ 59 9.2 Interface Detection ......................................................................................................................... 59 9.3 SPI Interface ....................................................................................................................................... 60 9.3.1 SPI Timing .............................................................................................................................. 60 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 6 of 158 Semtech 9.3.2 SPI Timing When the Transceiver is in Active Mode............................................... 61 9.3.3 SPI Timing When the Transceiver Leaves Sleep Mode .......................................... 62 9.4 UART Interface .................................................................................................................................. 64 9.4.1 Default UART Settings ....................................................................................................... 64 9.4.2 Setting the UART Speed.................................................................................................... 64 9.5 Pin Sharing ......................................................................................................................................... 64 9.6 Multi-Purpose Digital Input/Output (DIO) ............................................................................. 64 9.7 Transceiver Initialization on a Shared SPI Bus ....................................................................... 65 10. Operational Modes.................................................................................................................................... 67 10.1 Startup .............................................................................................................................................. 67 10.2 Sleep Mode ..................................................................................................................................... 67 10.3 Standby Mode ................................................................................................................................ 68 10.4 Frequency Synthesis (FS) Mode ............................................................................................... 68 10.5 Receive (Rx) Mode ......................................................................................................................... 68 10.6 Transmit (Tx) Mode ....................................................................................................................... 68 10.7 Transceiver Circuit Modes Graphical Illustration ............................................................... 69 10.8 Active Mode Switching Time .................................................................................................... 70 11. Host Controller Interface ......................................................................................................................... 71 11.1 Command Structure .................................................................................................................... 71 11.2 SetUartSpeed Command ........................................................................................................... 72 11.3 GetStatus Command ................................................................................................................... 72 11.4 Register Access Operations ....................................................................................................... 74 11.4.1 WriteRegister Command................................................................................................ 74 11.4.2 ReadRegister Command ................................................................................................ 75 11.5 Data Buffer Operations ............................................................................................................... 75 11.5.1 WriteBuffer Command .................................................................................................... 75 11.5.2 ReadBuffer........................................................................................................................... 76 11.6 Radio Operation Modes .............................................................................................................. 77 11.6.1 SetSleep................................................................................................................................ 77 11.6.2 SetStandby .......................................................................................................................... 78 11.6.3 SetFs....................................................................................................................................... 78 11.6.4 SetTx ...................................................................................................................................... 79 11.6.5 SetRx...................................................................................................................................... 80 11.6.6 SetRxDutyCycle ................................................................................................................. 81 11.6.7 SetLongPreamble ............................................................................................................. 82 11.6.8 SetCAD.................................................................................................................................. 83 11.6.9 SetTxContinuousWave.................................................................................................... 83 11.6.10 SetTxContinuousPreamble ......................................................................................... 83 11.6.11 SetAutoTx.......................................................................................................................... 84 11.6.12 SetAutoFs .......................................................................................................................... 85 11.7 Radio Configuration ..................................................................................................................... 85 11.7.1 SetPacketType.................................................................................................................... 85 11.7.2 GetPacketType................................................................................................................... 86 11.7.3 SetRfFrequency.................................................................................................................. 87 11.7.4 SetTxParams ....................................................................................................................... 87 11.7.5 SetCadParams .................................................................................................................... 88 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 7 of 158 Semtech 11.7.6 SetBufferBaseAddress ..................................................................................................... 89 11.7.7 SetModulationParams..................................................................................................... 89 11.7.8 SetPacketParams............................................................................................................... 90 11.8 Communication Status Information ...................................................................................... 92 11.8.1 GetRxBufferStatus............................................................................................................. 92 11.8.2 GetPacketStatus ................................................................................................................ 93 11.8.3 GetRssiInst ........................................................................................................................... 95 11.9 IRQ Handling ................................................................................................................................... 95 11.9.1 SetDioIrqParams................................................................................................................ 96 11.9.2 GetIrqStatus ........................................................................................................................ 97 11.9.3 ClearIrqStatus ..................................................................................................................... 97 12. List of Commands ...................................................................................................................................... 99 13. Register Map .............................................................................................................................................101 14. Transceiver Operation ............................................................................................................................104 14.1 GFSK Operation ...........................................................................................................................104 14.1.1 Common Transceiver Settings...................................................................................104 14.1.2 Tx Setting and Operations...........................................................................................110 14.1.3 Rx Setting and Operations...........................................................................................111 14.2 BLE Operation ...............................................................................................................................113 14.2.1 Common Transceiver Settings...................................................................................113 14.2.2 Tx Setting and Operations...........................................................................................116 14.2.3 Rx Setting and Operations...........................................................................................117 14.2.4 BLE Specific Functions ..................................................................................................119 14.3 FLRC Operation ............................................................................................................................121 14.3.1 Common Transceiver Settings...................................................................................121 14.3.2 Tx Setting and Operations...........................................................................................126 14.3.3 Rx Setting and Operations...........................................................................................127 14.4 LoRa® Operation ..........................................................................................................................130 14.4.1 Common Transceiver Settings for LoRa® ...............................................................130 14.4.2 Tx Setting and Operations...........................................................................................133 14.4.3 Rx Setting and Operations...........................................................................................134 14.5 Ranging Operation .....................................................................................................................136 14.5.1 Ranging Device Setting ................................................................................................136 14.5.2 Ranging Operation as State Machines ....................................................................140 14.5.3 Ranging RSSI.....................................................................................................................141 14.6 Advanced Ranging .....................................................................................................................142 14.6.1 Advanced Ranging Mode Operation.......................................................................142 14.6.2 Advanced Ranging State Machine .........................................................................143 14.7 Miscellaneous Functions ..........................................................................................................143 14.7.1 SetRegulatorMode Command ...................................................................................143 14.7.2 Context Saving.................................................................................................................144 15. Reference Design and Application Schematics ............................................................................145 15.1 Reference Design ........................................................................................................................145 15.1.1 Application Design Schematic...................................................................................145 15.1.2 Reference Design BOM .................................................................................................146 15.1.3 Reference Design PCB...................................................................................................146 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 8 of 158 Semtech 15.2 Application Design with optional TCXO .............................................................................147 15.3 Application Design with Low Drop Out Regulator .........................................................147 15.4 Sleep Mode Consumption .......................................................................................................148 16. Errata.............................................................................................................................................................149 16.1 All Modems: Continuous Receive Mode in Congested Traffic ................................... 149 16.1.1 Problem Description......................................................................................................149 16.1.2 Problem Solution ............................................................................................................149 16.2 LoRa Modem: Additional Header Checks Required .......................................................150 16.2.1 Problem Description......................................................................................................150 16.2.2 Problem Solution ............................................................................................................150 16.3 All Modems: Interrupt with Bad CRC ...................................................................................150 16.3.1 Problem Description......................................................................................................150 16.3.2 Problem Solution ............................................................................................................150 16.4 FLRC Modem: Increased PER in FLRC Packets with Synch Word ...............................151 16.4.1 Problem Description......................................................................................................151 16.4.2 Problem Solution ............................................................................................................151 17. Packaging Information...........................................................................................................................152 17.1 Package Outline Drawing ........................................................................................................152 17.2 Package Marking .........................................................................................................................153 17.3 Land Pattern .................................................................................................................................153 17.4 Reflow Profiles ..............................................................................................................................154 17.5 Thermal Impedance ...................................................................................................................154 17.6 Tape and Reel Specification ....................................................................................................154 Glossary ..............................................................................................................................................................155 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 9 of 158 Semtech List of Figures Figure 2-1: Transceiver Pin Locations ....................................................................................................... 18 Figure 4-1: Transceiver Block Diagram, Analog Front End Highlighted....................................... 28 Figure 5-1: Transceiver Block Diagram, Power Distribution Highlighted .................................... 32 Figure 5-2: Separate DIO Supply................................................................................................................. 33 Figure 6-1: Transceiver Block Diagram, Modems Highlighted ........................................................ 34 Figure 6-2: FSK Modulation Parameters................................................................................................... 41 Figure 6-3: Sensitivity Performance of the Transceiver Modems ................................................... 43 Figure 7-1: Transceiver Block Diagram, Packet Engine Highlighted.............................................. 44 Figure 7-2: Fixed-length Packet Format................................................................................................... 45 Figure 7-3: Variable-length Packet Format ............................................................................................. 45 Figure 7-4: BLE Packet Format..................................................................................................................... 46 Figure 7-5: PDU Header Format .................................................................................................................. 46 Figure 7-6: FLRC Fixed-length Packet Format........................................................................................ 47 Figure 7-7: FLRC Variable-length Packet Format .................................................................................. 48 Figure 7-8: LoRa® Variable-length Packet Format ................................................................................ 49 Figure 7-9: LoRa® Fixed-length Packet Format...................................................................................... 50 Figure 7-10: Ranging Packet Format......................................................................................................... 53 Figure 7-11: Ranging Master Packet Exchange ..................................................................................... 54 Figure 7-12: Ranging Slave Packet Exchange ........................................................................................ 54 Figure 7-13: Ranging Measurement.......................................................................................................... 56 Figure 8-1: Data Buffer Diagram ................................................................................................................. 57 Figure 9-1: Transceiver Block Diagram, Digital Interface Highlighted.......................................... 59 Figure 9-2: SPI Timing Diagram................................................................................................................... 61 Figure 9-3: SPI Wake-UpTiming Transition ............................................................................................. 62 Figure 9-4: SPI NSS Pulse Timing Transition ........................................................................................... 63 Figure 9-5: Multiple Radios Sharing an SPI Bus With a Sensor......................................................... 66 Figure 10-1: Transceiver Circuit Modes .................................................................................................... 69 Figure 10-2: Switching Time Definition in Active Mode .................................................................... 70 Figure 14-1: Ranging Application State Machine Diagram............................................................. 140 Figure 14-2: Example Ranging RSSI Response (may vary depending upon SF BW used) ... 141 Figure 14-3: ...................................................................................................................................................... 143 Figure 14-4: Advanced Ranging Mode State Machine ..................................................................... 143 Figure 15-1: Transceiver Application Design Schematic ................................................................. 145 Figure 15-2: Long Range Reference Design PCB Layout.................................................................. 146 Figure 15-3: Application Schematic with Optional TCXO................................................................ 147 Figure 15-4: Application Schematic with Low Drop Out Regulator Schematic ...................... 147 Figure 17-1: QFN 4x4 Package Outline Drawing................................................................................. 152 Figure 17-2: SX1280 and SX1281 Package Marking .......................................................................... 153 Figure 17-3: QFN 4x4mm Land Pattern.................................................................................................. 153 Figure 17-4: Tape and Reel Specification .............................................................................................. 154 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 10 of 158 Semtech List of Tables Table 1-1: Product Portfolio and Modem Functionality..................................................................... Table 2-1: Transceiver Pinout....................................................................................................................... Table 3-1: Minimum and Maximum Ratings .......................................................................................... Table 3-2: Operating Range.......................................................................................................................... Table 3-3: General Electrical Specifications ............................................................................................ Table 3-4: Receiver Specifications .............................................................................................................. Table 3-5: LoRa® Modem Specifications .................................................................................................. Table 3-6: FLRC Modem Specifications .................................................................................................... Table 3-7: FSK Modem Specifications ....................................................................................................... Table 3-8: Transmitter Electrical Specifications..................................................................................... Table 3-9: Crystal Oscillator Specifications ............................................................................................. Table 3-10: Digital Levels and Timings..................................................................................................... Table 4-1: Procedure for Receiver Gain Manual Setting..................................................................... Table 4-2: Receiver Gain Manual Setting ................................................................................................. Table 5-1: Regulation Type versus Circuit Mode................................................................................... Table 6-1: Receiver Sensitivity when using LoRa® in Low Power Mode ....................................... Table 6-2: Raw Data Rates when using LoRa®........................................................................................ Table 6-3: Total Permissible Reference Drift........................................................................................... Table 6-4: Valid FLRC Data Rate and Bandwidth Combinations .................................................... Table 6-5: Effective FLRC Data Rates Based upon FEC Usage with Resulting Sensitivities.... Table 6-6: Receiver Performance of the FLRC Modem ....................................................................... Table 6-7: Valid FSK Data Rate and Bandwidth Combinations with Resulting Sensitivities . Table 9-1: SPI Timing Requirements.......................................................................................................... Table 10-1: SX1280 Operating Modes ...................................................................................................... Table 10-2: Switching Time (TswMode) for all Possible Transitions .............................................. Table 11-1: SPI interface Command Sequence ..................................................................................... Table 11-2: UART Interface Command Sequence ................................................................................ Table 11-3: SetUartSpeed Data Transfer (UART only) ......................................................................... Table 11-4: Divider Ratios to Configure the UART Interface Speed ............................................... Table 11-5: Status Byte Definition.............................................................................................................. Table 11-6: GetStatus Data Transfer (SPI) ................................................................................................ Table 11-7: GetStatus Data Transfer (UART) ........................................................................................... Table 11-8: WriteRegister Data Transfer (SPI)......................................................................................... Table 11-9: WriteRegister Data Transfer (UART).................................................................................... Table 11-10: ReadRegister Data Transfer (SPI)....................................................................................... Table 11-11: ReadRegister Data Transfer (UART).................................................................................. Table 11-12: WriteBuffer SPI Data Transfer ............................................................................................. Table 11-13: WriteBuffer UART Data Transfer ........................................................................................ Table 11-14: ReadBuffer SPI Data Transfer.............................................................................................. Table 11-15: ReadBuffer UART Data Transfer......................................................................................... Table 11-16: SetSleep SPI Data Transfer................................................................................................... Table 11-17: Sleep Mode Definition .......................................................................................................... Table 11-18: SetStandby SPI Data Transfer............................................................................................. Table 11-19: SetStandby UART Data Transfer........................................................................................ Table 11-20: StandbyConfig Definition.................................................................................................... Table 11-21: SetFs Data Transfer ................................................................................................................ Table 11-22: SetTx SPI Data Transfer ......................................................................................................... Table 11-23: SetTx UART Data Transfer .................................................................................................... Table 11-24: SetTx Time-out Definition. .................................................................................................. Table 11-25: SetTx Time-out Duration...................................................................................................... SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 15 17 19 19 20 21 22 24 25 26 26 27 29 29 32 35 36 37 38 39 40 42 60 67 70 71 71 72 72 73 73 73 74 74 75 75 75 76 76 76 77 77 78 78 78 79 79 79 79 80 11 of 158 Semtech Table 11-26: SetRx SPI Data Transfer......................................................................................................... Table 11-27: SetRx UART Data Transfer.................................................................................................... Table 11-28: SetRx Time-out Duration ..................................................................................................... Table 11-29: Duty Cycled Operation SPI Data Transfer ...................................................................... Table 11-30: Duty Cycled Operation UART Data Transfer ................................................................. Table 11-31: Rx Duration Definition. ......................................................................................................... Table 11-32: SetLongPreamble Data Transfer ....................................................................................... Table 11-33: SetCAD Data Transfer............................................................................................................ Table 11-34: SetTxContinuousWave Data Transfer.............................................................................. Table 11-35: SetTxContinuousPreamble Data Transfer ..................................................................... Table 11-36: SetAutoTx SPI Data Transfer ............................................................................................... Table 11-37: SetAutoTx UART Data Transfer .......................................................................................... Table 11-38: SetAutoFs SPI Data Transfer ............................................................................................... Table 11-39: SetAutoFs UART Data Transfer........................................................................................... Table 11-40: SetPacketType SPI Data Transfer ...................................................................................... Table 11-41: SetPacketType UART Data Transfer ................................................................................. Table 11-42: PacketType Definition........................................................................................................... Table 11-43: GetPacketType SPI Data Transfer...................................................................................... Table 11-45: SetRfFrequency SPI Data Transfer .................................................................................... Table 11-46: SetRfFrequency UART Data Transfer ............................................................................... Table 11-47: SetTxParams SPI Data Transfer .......................................................................................... Table 11-44: GetPacketType UART Data Transfer................................................................................. Table 11-49: RampTime Definition ............................................................................................................ Table 11-50: CAD SPI Data Transfer ........................................................................................................... Table 11-51: CAD UART Data Transfer ...................................................................................................... Table 11-48: SetTxParams UART Data Transfer ..................................................................................... Table 11-52: CadSymbolNum Definition................................................................................................. Table 11-53: SetBufferBaseAddress SPI Data Transfer ........................................................................ Table 11-54: SetBufferBaseAddress UART Data Transfer ................................................................... Table 11-55: SetModulationParams SPI Data Transfer ....................................................................... Table 11-57: SetModulationParams Parameters Definition.............................................................. Table 11-58: SetPacketParams SPI Data Transfer.................................................................................. Table 11-56: SetModulationParams UART Data Transfer .................................................................. Table 11-60: SetPacketParams Parameters Definition........................................................................ Table 11-59: SetPacketParams UART Data Transfer............................................................................. Table 11-61: GetRxBufferStatus SPI Data Transfer ............................................................................... Table 11-62: GetRxBufferStatus UART Data Transfer .......................................................................... Table 11-63: GetPacketStatus SPI Data Transfer ................................................................................... Table 11-64: GetPacketStatus UART Data Transfer .............................................................................. Table 11-65: packetStatus Definition........................................................................................................ Table 11-66: RSSI and SNR Packet Status................................................................................................. Table 11-67: Status Packet Status Byte..................................................................................................... Table 11-68: Error Packet Status Byte ....................................................................................................... Table 11-69: Sync Packet Status Byte........................................................................................................ Table 11-70: GetRssiInst SPI Data Transfer.............................................................................................. Table 11-71: GetRssiInst UART Data Transfer ......................................................................................... Table 11-72: RssiInst Definition ................................................................................................................... Table 11-73: IRQ Register............................................................................................................................... Table 11-74: IRQ Mask Definition SPI Data Transfer ............................................................................ Table 11-75: IRQ Mask Definition UART Data Transfer ....................................................................... Table 11-76: GetIrqStatus SPI Data Transfer........................................................................................... Table 11-77: GetIrqStatus UART Data Transfer...................................................................................... Table 11-78: ClearIrqStatus SPI Data Transfer........................................................................................ Table 11-79: ClearIrqStatus UART Data Transfer................................................................................... SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 80 80 81 81 81 82 83 83 83 84 84 84 85 85 86 86 86 86 87 87 87 87 88 88 88 88 89 89 89 89 90 90 90 91 91 92 92 93 93 93 93 94 94 94 95 95 95 95 96 96 97 97 97 97 12 of 158 Semtech Table 12-1: Transceiver Available Commands....................................................................................... 99 Table 13-1: List of Registers ........................................................................................................................ 101 Table 14-1: Modulation Parameters in GFSK Mode ........................................................................... 104 Table 14-2: Modulation Index Parameters in GFSK Mode............................................................... 105 Table 14-3: Modulation Shaping Parameters in GFSK Mode.......................................................... 106 Table 14-4: Preamble Length Definition in GFSK Packet ................................................................. 106 Table 14-5: Sync Word Length Definition in GFSK Packet............................................................... 107 Table 14-6: Sync Word Combination in GFSK Packet........................................................................ 107 Table 14-7: Packet Type Definition in GFSK Packet ........................................................................... 107 Table 14-8: Payload Length Definition in GFSK Packet .................................................................... 108 Table 14-9: CRC Definition in GFSK Packet ........................................................................................... 108 Table 14-10: Whitening Enabling in GFSK Packet .............................................................................. 108 Table 14-11: Sync Word Definition in GFSK Packet............................................................................ 108 Table 14-12: CRC Initialization Registers................................................................................................ 109 Table 14-13: CRC Polynomial Definition ................................................................................................ 109 Table 14-14: PacketStatus[3] in GFSK Packet ....................................................................................... 110 Table 14-15: PacketStatus[2] in GFSK Packet ....................................................................................... 112 Table 14-16: PacketStatus[4] in GFSK Mode Packet........................................................................... 112 Table 14-17: Modulation Parameters in BLE and GFSK Mode........................................................ 113 Table 14-18: Modulation Parameters in BLE and GFSK Mode........................................................ 114 Table 14-19: Modulation Parameters in BLE and GFSK Mode........................................................ 114 Table 14-20: Connection State Definition in BLE Packet.................................................................. 114 Table 14-21: CRC Definition in BLE Packet ............................................................................................ 114 Table 14-22: Tx Test Packet Payload in Test Mode for BLE Packet ............................................... 115 Table 14-23: Whitening Enabling in BLE Packet.................................................................................. 115 Table 14-24: Access Address Definition in BLE Packet...................................................................... 116 Table 14-25: CRC Initialization Registers................................................................................................ 116 Table 14-26: BLE Access Address Configuration for Tx..................................................................... 116 Table 14-27: PacketStatus3 in BLE Packet ............................................................................................. 117 Table 14-28: PacketStatus2 in BLE Mode............................................................................................... 118 Table 14-29: PacketStatus4 in BLE Mode............................................................................................... 119 Table 14-30: SetAutoTx Mode ................................................................................................................... 119 Table 14-31: Modulation Parameters in FLRC Mode: Bandwidth and Bit Rate........................ 121 Table 14-32: Modulation Parameters in FLRC Mode: Coding Rate .............................................. 122 Table 14-33: Modulation Parameters in FLRC Mode: BT .................................................................. 122 Table 14-34: AGC Preamble Length Definition in FLRC Packet ..................................................... 122 Table 14-35: Sync Word Length Definition in FLRC Packet............................................................. 123 Table 14-36: Sync Word Combination in FLRC Packet...................................................................... 123 Table 14-37: Packet Type Definition in FLRC Packet ......................................................................... 124 Table 14-38: Payload Length Definition in FLRC Packet .................................................................. 124 Table 14-39: CRC Definition in FLRC Packet ......................................................................................... 124 Table 14-40: CRC Initialization Registers................................................................................................ 125 Table 14-41: Whitening Definition in FLRC Packet............................................................................. 125 Table 14-42: Sync Word Definition in FLRC Packet ............................................................................ 125 Table 14-43: PacketStatus3 in FLRC Packet .......................................................................................... 127 Table 14-44: PacketStatus2 in FLRC Packet .......................................................................................... 128 Table 14-45: PacketStatus3 in FLRC Packet .......................................................................................... 128 Table 14-46: PacketStatus4 in FLRC Packet .......................................................................................... 129 Table 14-47: Modulation Parameters in LoRa® Mode ....................................................................... 130 Table 14-48: Modulation Parameters in LoRa® Mode ....................................................................... 131 Table 14-49: Modulation Parameters in LoRa® Mode ....................................................................... 131 Table 14-50: Preamble Definition in LoRa® or Ranging.................................................................... 132 Table 14-51: Packet Type Definition in LoRa® or Ranging Packet ................................................ 132 Table 14-52: Payload Length Definition in LoRa® Packet ................................................................ 132 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 13 of 158 Semtech Table 14-53: CRC Enabling in LoRa® Packet.......................................................................................... 132 Table 14-54: IQ Swapping in LoRa® or Ranging Packet .................................................................... 133 Table 14-55: LoRa FEI Measurement Resolution [Hz ]....................................................................... 135 Table 14-56: Ranging Device Modulation Parameters ..................................................................... 136 Table 14-57: Slave Ranging Request Address Definition................................................................. 137 Table 14-58: Register Address Bit Definition........................................................................................ 137 Table 14-59: Master Ranging Request Address Definition.............................................................. 137 Table 14-60: Calibration Value in Register ............................................................................................ 138 Table 14-61: Ranging Role Value .............................................................................................................. 138 Table 14-62: Register Result Address ...................................................................................................... 139 Table 14-63: Ranging Result Type Selection ........................................................................................ 139 Table 14-64: Power Regulation Selection SPI Data Transfer........................................................... 143 Table 14-65: Power Regulation Selection UART Data Transfer...................................................... 143 Table 14-66: RegModeParam Definition................................................................................................ 143 Table 14-67: SetSaveContext Data Transfer ......................................................................................... 144 Table 15-1: Reference Design BOM ......................................................................................................... 146 Table 15-2: Host Settings for Minimizing Sleep Mode Consumption ......................................... 148 Table 17-1: Tape and Reel Specification ................................................................................................ 154 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 14 of 158 Semtech 1. Introduction The SX1280 and SX1281 are half-duplex transceivers capable of low power operation in the worldwide 2.4 GHz ISM band. The radio comprises 5 main parts, which are described in the following chapters. 1.1 Analog Front End The radio features a high efficiency +12.5 dBm transmitter and a high linearity receive chain that are both accessed via a common antenna port pin. Frequency conversion between RF and baseband (low-IF) is governed by a digital PLL that is referenced to a 52 MHz crystal. Both transmit and receive chains are interfaced by data converters to the ensuing digital blocks. For more information see the Section 4. "Analog Front End" on page 28 . 1.2 Power Distribution Two forms of voltage regulation are available, either a integrated Low-DropOut (LDO) or a high efficiency buck (step down) DC to DC converter. This allows the designer to choose between high energy efficiency or miniaturisation of the radio depending upon the design priorities of the application. For more information, please see the Section 5. "Power Distribution" on page 32 . 1.3 Modem There are a range of modulation options available in the LoRa® family’s three modems, each of which has packet options that include many MAC layer functionalities. For a description of each modulation format and the performance benefits associated with that modulation, please see the corresponding section below: • LoRa® Modem and Packet: Section 6.2 "LoRa® Modem" on page 35 • FLRC Modem and Packet: Section 6.3 "FLRC Modem" on page 38 • FSK Modem and Packet: Section 6.4 "FSK Modem" on page 41 The long range 2.4 GHz product line also features the Ranging Engine, a long distance ranging functionality that permits round-trip time-of-flight measurement between a pair of LoRa® radios. The availability of each modem and the Ranging Engine, for each part number in the long range 2.4 GHz product line is shown below. Table 1-1: Product Portfolio and Modem Functionality Product Reference SX1280 SX1281 LoRa®   FLRC   GFSK   Ranging Engine  Advanced Ranging  SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 15 of 158 Semtech 1.4 Packet Processing The radio can operate in a fully automatic mode where the processing of packets for transmission or reception can be performed without the intervention of an external host micro-controller. For more details see Section 7. "Packet Engine" on page 44 . In both transmit and receive modes the payload interface to the transceiver is the packet data buffer described in Section 8. "Data Buffer" on page 57 of this datasheet. 1.5 Digital Interface and Control The specification and processing for all digital communication with the transceiver is described in Section 9. "Digital Interface and Control" on page 59 . This includes descriptions of the SPI and UART interfaces, that can be used to configure the transceiver together with the Digital Input / Output (DIO) that are used to send interrupts to an external host micro-controller. • For the SPI interface see Section 9.3 "SPI Interface" on page 60 • For the UART interface see Section 9.4 "UART Interface" on page 64 • For the DIO see Section 9.6 "Multi-Purpose Digital Input/Output (DIO)" on page 64 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 16 of 158 Semtech 2. Pin Connections 2.1 Transceiver Pinout Table 2-1: Transceiver Pinout Pin Number Pin Name Type (I = input O = Output) 0 GND - Exposed Ground pad 1 VR_PA - Regulated supply for the PA 2 VDD_IN I Regulated supply input. Connect to Pin 12. 3 NRESET I Reset signal, active low with internal pull-up at 50 kΩ 4 XTA - Reference oscillator connection or TCXO input 5 GND - Ground 6 XTB - Reference oscillator connection 7 BUSY O Transceiver busy indicator 8 DIO1 I/O Optional multi-purpose digital I/O 9 DIO2 I/O Optional multi-purpose digital I/O 10 DIO3 I/O Optional multi-purpose digital I/O 11 VBAT_IO I Supply for the Digital IO interface (1.8 V to 3.7 V). Must be ≤ VBAT. 12 DCC_FB O Regulated output voltage from the internal regulator 13 GND - Ground 14 DCC_SW O DC-DC Switcher Output 15 VBAT I Supply for the RFIC (1.8 V to 3.7 V). Must be ≥ VBAT_IO. 16 MISO_TX O SPI slave output UART Transmit pin 17 MOSI_RX I SPI slave input UART Receive pin 18 SCK_RTSN I SPI clock UART Request To Send 19 NSS_CTS I SPI Slave Select UART Clear To Send 20 GND - Ground 21 GND - Ground 22 RFIO I/O RF transmit output and receive input 23 GND - Ground 24 GND - Ground SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP SPI description www.semtech.com Rev 3.2 March 2020 UART description 17 of 158 Semtech GND NSS_CTS 20 19 RFIO 22 GND GND 23 21 GND 24 2.2 Package view VR_PA 1 18 SCK_RTSN VDD_IN 2 17 MOSI_RX NRESET 3 16 MISO_TX XTA 4 15 VBAT GND 5 14 DCC_SW XTB 6 13 GND 11 12 VBAT_IO DCC_FB 10 DIO3 9 DIO2 8 DIO1 BUSY 7 0 GND Figure 2-1: Transceiver Pin Locations SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 18 of 158 Semtech 3. Specifications The following specifications are given for the typical operating conditions of VBAT_IO = VBAT = 3.3 V, temperature = 25 °C, crystal oscillator frequency = 52 MHz, RF centre frequency = 2.4 GHz. All RF impedances are matched using the reference design, see Section 15.1 "Reference Design" on page 145. Blocking, ACR and co-channel rejection are given for a single tone interferer and referenced to sensitivity level +6 dB. The current supply is given as the sum of current on VBAT and VBAT_IO. The buck converter (DC-DC) is considered switched ON unless otherwise stated. 3.1 ESD Notice The SX1280/SX1281 transceivers are high-performance radio frequency devices. They all satisfy: • Class 2 of the JEDEC standard JESD22-A114 (Human Body Model) on all pins • Class III of the JEDEC standard JESD22-C101 (Charged Device Model) on all pins 3.2 Absolute Minimum and Maximum Ratings Table 3-1: Minimum and Maximum Ratings Symbol Description Minimum Typical Maximum Unit VBATmr Supply voltage on VBAT and VBAT_IO -0.5 - 3.9 V Tmr Temperature -55 - 115 °C Pmr RF Input level - - 10 dBm Minimum Typical Maximum Unit 1.8 - 3.7 V 3.3 Operating Range Table 3-2: Operating Range Symbol VBATop Description Supply voltage VBAT and VBAT_IO Top Temperature under bias -40 - 85 °C Clop Load capacitance on digital ports - - 10 pF ML RF Input power - - 0 dBm SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 19 of 158 Semtech 3.4 General Electrical Specifications Table 3-3: General Electrical Specifications Symbol Description Minimum Typical Maximum Unit Supply current in Sleep mode with - data RAM not retained - data buffer retained - 0.215 1.0 μA Supply current in Sleep mode with - data RAM retained (context saved) - data buffer flushed - 0.25 1.0 μA Supply current in Sleep mode with - data RAM retained - data buffer retained - 0.4 1.0 μA Supply current in Sleep mode with - data RAM retained - data buffer retained - RC64k is running - 1.2 1.8 μA IDDSTDBYRC Supply current in STDBY_RC mode - 700 - μA IDDSTDBYXOSC Supply current in STDBY_XOSC mode - 1 - mA IDDFS Supply current in FS mode - 2.8 - mA FR Synthesizer frequency range 2400 - 2500 MHz - 198 - Hz 1 MHz offset - -115 - dBc/Hz 10 MHz offset - -135 - dBc/Hz FXOSC Crystal oscillator frequency - 52 - MHz TS_FS Frequency synthesizer wake-up time with XOSC enabled - 54 - μs IDDSL FSTEP Synthesizer frequency step (52 MHz reference) Phase noise at 2.45 GHz PHN Frequency synthesizer hop time to within 10 kHz of target frequency 1 MHz - 20 - μs 10 MHz - 30 - μs 100 MHz - 50 - μs Crystal oscillator wake-up time from STDBY_RC mode - 40 - μs TS_HOP TS_OS For the digital specifications, see Table 10-2: "Switching Time (TswMode) for all Possible Transitions" on page 70. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 20 of 158 Semtech 3.5 Receiver Electrical Specifications All receiver sensitivity numbers are given for a Packer Error Rate (PER) of 1%, for packet with 10 bytes of payload. Values are given for maximum AGC gain which is the highest low power gain. A continuous wave (CW) interferer is used for all blocking and rejection measurements unless otherwise stated. 3.5.1 Receiver Specifications Table 3-4: Receiver Specifications Symbol Description Minimum Typical Maximum Unit 3rd Order input intercept for maximum low power gain setting IIP3 IMR SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP In-band interferer SF10 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 50 of 158 Semtech With: • Nbit_CRC = 16 if CRC activated, 0 if not • Nsymbol_header = 20 if header is variable, 0 if it is fixed • CR is 1, 2, 3 or 4 for respective coding rates 4/5, 4/6, 4/7 or 4/8 7.4.4.2 For Long Interleaving With Header: if SF < SF7: ܰ௕௜௧̴௛௘௔ௗ௘௥̴௦௣௔௖௘ ൌ ݂݈‫ ݎ݋݋‬൬ If ܵ‫ ܨ‬െ ͷ ൰‫כ‬ͺ ʹ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ൐ ܰ௕௜௧̴௛௘௔ௗ௘௥̴௦௣௔௖௘ ܰ௦௬௠௕௢௟ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͸Ǥʹͷ ൅ ͺ ൅ ݈ܿ݁݅ ቌ ƒš ቀͲǡͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ െ ‹ሺͺ ‫ ݎ݋݋݈݂ כ‬ቀ Ͷ ‫ܨܵ כ‬ ܵ‫ ܨ‬െ ͷ ቁ ǡ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ሻቁ ʹ ‫ܴܥ כ‬ቍ Else ܰ௦௬௠௕௢௟ ‫ۇ‬ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͸Ǥʹͷ ൅ ͺ ൅ ݈ܿ݁݅ ‫ۈ‬ ƒš ቆͲǡͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ െ ͺ ‫ ݎ݋݋݈݂ כ‬ቀ ܵ‫ ܨ‬െ ͷ ቁቇ ʹ Ͷ ‫ܨܵ כ‬ ‫ۉ‬ ‫ۊ‬ ‫ۋܴܥ כ‬ ‫ی‬ if SF7 ≤ SF ≤ SF10: ܰ௕௜௧̴௛௘௔ௗ௘௥̴௦௣௔௖௘ ൌ ݂݈‫ ݎ݋݋‬൬ ܵ‫ ܨ‬െ ͹ ൰‫כ‬ͺ ʹ If ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ൐ ܰ௕௜௧̴௛௘௔ௗ௘௥̴௦௣௔௖௘ ܰ௦௬௠௕௢௟ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͶǤʹͷ ൅ ͺ ൅ ݈ܿ݁݅ ቌ ƒš ቀͲǡͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ െ ‹ሺͺ ‫ ݎ݋݋݈݂ כ‬ቀ Ͷ ‫ܨܵ כ‬ ܵ‫ ܨ‬െ ͹ ቁ ǡ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ሻቁ ʹ ‫ܴܥ כ‬ቍ Else ܰ௦௬௠௕௢௟ ‫ۇ‬ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͶǤʹͷ ൅ ͺ ൅ ݈ܿ݁݅ ‫ۈ‬ ƒš ቆͲǡͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ െ ͺ ‫ ݎ݋݋݈݂ כ‬ቀ ܵ‫ ܨ‬െ ͹ ቁቇ ʹ Ͷ ‫ܨܵ כ‬ ‫ۉ‬ ‫ۊ‬ ‫ۋܴܥ כ‬ ‫ی‬ if SF > SF10: ܰ௕௜௧_௛௘௔ௗ௘௥_௦௣௔௖௘ = ݂݈‫ ݎ݋݋‬൬ ܵ‫ ܨ‬െ 7 ൰‫כ‬8 2 If 8 ‫ܰ כ‬஻௬௧௘_௣௔௬௟௢௔ௗ + ܰ௕௜௧_஼ோ஼ > ܰ௕௜௧_௛௘௔ௗ௘௥_௦௣௔௖௘ ܰ௦௬௠௕௢௟ = ܰ௦௬௠௕௢௟_௣௥௘௔௠௕௟௘ + 4.25 + 8 + ݈ܿ݁݅ ቌ max ቀ0,8 ‫ܰ כ‬஻௬௧௘_௣௔௬௟௢௔ௗ + ܰ௕௜௧_஼ோ஼ െ min(8 ‫ ݎ݋݋݈݂ כ‬ቀ 4 ‫ ܨܵ( כ‬െ 2) ܵ‫ ܨ‬െ 7 ቁ , 8 ‫ܰ כ‬஻௬௧௘_௣௔௬௟௢௔ௗ )ቁ 2 ‫ܴܥ כ‬ቍ Else ܰ௦௬௠௕௢௟ ‫ۇ‬ = ܰ௦௬௠௕௢௟_௣௥௘௔௠௕௟௘ + 4.25 + 8 + ݈ܿ݁݅ ‫ۈ‬ max ቆ0,8 ‫ܰ כ‬஻௬௧௘_௣௔௬௟௢௔ௗ + ܰ௕௜௧_஼ோ஼ െ 8 ‫ ݎ݋݋݈݂ כ‬ቀ 4 ‫ ܨܵ( כ‬െ 2) ‫ۉ‬ ܵ‫ ܨ‬െ 7 ቁቇ 2 ‫ۊ‬ ‫ۋܴܥ כ‬ ‫ی‬ With: SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 51 of 158 Semtech • Nbit_CRC = 16 if CRC activated, 0 if not • Nsymbol_header = 20 if header is variable, 0 if it is fixed • CR is 5, 6, or 8 for respective coding rates 4/5LI, 4/6LI, or 4/8LI Without Header  ൏  ͹ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ܰ௦௬௠௕௢௟̴௕௘௚௜௡௜௡௚ ൌ ݈ܿ݁݅ ൬ ‫ܴܥ כ‬൰ Ͷ ‫ܨܵ כ‬ If ܰ௦௬௠௕௢௟̴௕௘௚௜௡௜௡௚ ൑ ͺ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ܰ௦௬௠௕௢௟ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͸Ǥʹͷ ൅ ݈ܿ݁݅ ൬ ‫ܴܥ כ‬൰ Ͷ ‫ܨܵ כ‬ Else ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ‫ ܴܥ כ‬െ ͺ൰ ܰ௦௬௠௕௢௟ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͸Ǥʹͷ ൅ ͺ ൅ ݈ܿ݁݅ ൬ Ͷ ‫ܨܵ כ‬  ͹ ൑  ൑  ͳͲ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ܰ௦௬௠௕௢௟̴௕௘௚௜௡௜௡௚ ൌ ݈ܿ݁݅ ൬ ‫ܴܥ כ‬൰ Ͷ ‫ כ‬ሺܵ‫ ܨ‬െ ʹሻ If ܰ௦௬௠௕௢௟̴௕௘௚௜௡௜௡௚ ൑ ͺ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ‫ܴܥ כ‬൰ ܰ௦௬௠௕௢௟ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͶǤʹͷ ൅ ݈ܿ݁݅ ൬ Ͷ ‫ כ‬ሺܵ‫ ܨ‬െ ʹሻ Else ൫ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ൯ ‫ ܴܥ כ‬൅ ͸Ͷ െ ͺቇ ܰ௦௬௠௕௢௟ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͶǤʹͷ ൅ ͺ ൅ ݈ܿ݁݅ ቆ Ͷ ‫ܨܵ כ‬  ൐  ͳͲ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ܰ௦௬௠௕௢௟̴௕௘௚௜௡௜௡௚ ൌ ݈ܿ݁݅ ൬ ‫ܴܥ כ‬൰ Ͷ ‫ כ‬ሺܵ‫ ܨ‬െ ʹሻ If ܰ௦௬௠௕௢௟̴௕௘௚௜௡௜௡௚ ൑ ͺ ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ‫ܴܥ כ‬൰ ܰ௦௬௠௕௢௟ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͶǤʹͷ ൅ ݈ܿ݁݅ ൬ Ͷ ‫ כ‬ሺܵ‫ ܨ‬െ ʹሻ Else ͺ ‫ܰ כ‬஻௬௧௘̴௣௔௬௟௢௔ௗ ൅ ܰ௕௜௧̴஼ோ஼ ‫ ܴܥ כ‬െ ͺ൰ ܰ௦௬௠௕௢௟ ൌ ܰ௦௬௠௕௢௟̴௣௥௘௔௠௕௟௘ ൅ ͶǤʹͷ ൅ ͺ ൅ ݈ܿ݁݅ ൬ Ͷ ‫ כ‬ሺܵ‫ ܨ‬െ ʹሻ SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 52 of 158 Semtech 7.5 LoRa® Ranging Engine Packet A detailed explanation of the ranging functionality can be found in the application note “An Introduction to Ranging with the SX1280 Transceiver” available on www.semtech.com. The ranging operation consists of an exchange, or sequence of exchanges, between a transceiver configured as a ranging Master and a transceiver configured as a ranging Slave. In each exchange the Master generates a ranging packet that is sent over the air and received by the Slave. The Slave then synchronises with the incoming ranging packet and sends a ranging response. When received by the Master, synchronisation with the ranging response allows the deduction of the time of flight between the Master and the Slave. This can be converted into distance. It should be noted that the distance reported will be representative of the path travelled by the radio wave rather than the shortest path distance between the Master and the Slave. The Ranging Engine Packet structure is very similar to the LoRa® packet explicit header mode (see Section 7.4.2 "Explicit (Variable-length) Header Mode" on page 49). One reserved bit in the header is simply set to indicate that a packet is a ranging request. The header includes a 32-bit ranging Slave ID. The slave will reject any ranging request that does not have a matching ID. To afford some flexibility to the system, the Slave may also check a portion of the ranging ID, specifically the least significant 8, 16, 24, or 32 bits. The time-of-flight reported by the master is available in both raw format - where the result for a single ranging measurement is reported - or in filtered format. Filtering applies a non-linear filtering function to aggregate several ranging exchanges results and improve accuracy. For configuration of the filtering and the ranging parameters please see Section 14.5 "Ranging Operation" on page 136 for more details. 7.5.1 Ranging Packet Format The following figure shows the dedicated frames used in ranging exchange: Master Preamble Ranging symbols Slave Header ranging indication + ID MSB + CRC + 2 bits reserved Header extension ID LSB + PAD bits Ranging response Figure 7-10: Ranging Packet Format SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 53 of 158 Semtech 7.5.2 Ranging Master Exchange Silence is at least 1 symbol SetTx() Master Transmit Receive Slave response Ranging sync Timing sync CLK counter Tx start CFG_RC mode Tx mode Rx mode CFG_RC mode Figure 7-11: Ranging Master Packet Exchange The entire ranging exchange, seen from the perspective of the ranging Master is shown above. The ranging exchange is initiated by the Master which transmits the ranging request. Following the transmit phase, master then switches to receive mode to await the ranging response from the Slave. The waiting delay noted Nranging_symbol_silence is deterministic and corresponds to the required time for the ranging Slave to process the ranging request. 7.5.3 Ranging Slave Exchange Silence is at least 1 symbol SetRx() Detect / Sync / Receive Master request Ranging sync Transmit Slave response Timing sync CLK counter Rx start CFG_RC mode Rx mode Tx mode CFG_RC mode Figure 7-12: Ranging Slave Packet Exchange From the perspective of the Slave, the radio must already be in Slave mode to receive the ranging request from the Master. Upon reception of ranging request the Slave checks the ranging request address and determines if it should answer it with a ranging response (see Section 14.5.1 "Ranging Device Setting" on page 136 for detailed configuration of ranging request address checking mechanism). If the ranging Slave must send a ranging response, it waits for a strict period of one LoRa® symbol from ranging request end of reception to be exhausted to start transmitting the ranging response. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 54 of 158 Semtech 7.5.4 Total Exchange Duration The ranging time-on-air only depends on the following elements: • SF (from setModulationParams) • BW (from setModulationParams) • Preamble length (from setPacketParams) • Number of ranging symbols • The silence in switching slave from Rx to Tx It does not depend on the following: • Coding rate (from setModulationParams) • Header type (from setPacketParams) • Payload length (from setPacketParams) • CRC mode (from setPacketParams) Where: is the deterministic symbol equivalent duration of the silence between end of ranging request reception and beginning of ranging response transmission is the number of actual preamble symbols sent, depending on user configured preamble is the number of symbols in LoRa ranging header Which gives: Similarly to the detailed expression of complete ranging Time on Air, it is possible to express the Time on Air specific to Master and Slave (useful for consumption computation) as the following: SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 55 of 158 Semtech 7.5.4.1 Example of Time-on-Air Computation Configuration • BW = 1625 kHz • SF6 • Nsymbol_preamble = 12 • Nranging_symbols = 15 • Nranging_symbol_delay = 2 Results: • Tranging = 2.53 ms • Tranging_master_tx = 1.86 ms • Tranging_slave_tx = 0.59 ms 7.5.5 Measurement The image below shows a radiated measurement of a ranging exchange at identical settings to those above, the Master transmission is seen first, followed by the remote (weaker) Slave response. Within the timing resolution measurement step of the spectrum analyzer (20 μs), the results (M1 and M2) match our prediction. Figure 7-13: Ranging Measurement SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 56 of 158 Semtech 8. Data Buffer The transceiver is equipped with a 256 byte RAM data buffer which is accessible in all modes except sleep mode. This memory space is fully customizable by the user and allows access to either data for transmission or from packet reception. All access to the data buffer is via either the SPI or UART interfaces of Section 9. "Digital Interface and Control" on page 59. 8.1 Principle of Operation 0xFF USER TRANSCEIVER txBaseAddress + txPayloadLength TxDataPointer WriteBuffer() Transmitted Payload SetBufferBaseAddress() rxBaseAddress + rxPayloadLength Received Payload GetRxBufferStatus() RxDataPointer SetBufferBaseAddress() 0x00 Data buffer Capacity = 256 bytes Figure 8-1: Data Buffer Diagram The data buffer can be configured to store both transmit and receive payloads. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 57 of 158 Semtech 8.2 Receive Operation In receive mode rxBaseAddress specifies the buffer offset in memory at which the received packet payload data will be written. The RxDataPointer which is initialized to the value rxBaseAddress at the beginning of the reception and subsequently updated to the tuhe buffer offset of last byte of the packet. The pointer to the first byte of the last packet received and the packet length can be read via command GetRxbufferStatus(). In single and continuous mode, RxDataPointer is automatically initialized to rxBaseAddress each time the transceiver enters to Rx. In continuous mode the receiver remains in Rx, and for each new reception, the pointer is incremented starting from the previous position. Therefore, if several packets are received in continuous mode, it is not possible to retrieve the base address and size of each one of the packets. A call to GetRxBufferStatus() will return the pointer to the first byte and size of only the last received packet. It is important to note that should the received packets exceed the size of the data buffer, then the pointer index will wrap around to zero. 8.3 Transmit Operation Upon each transition to transmit mode the pointer TxDataPointer is initialised to the txBaseAddress and is incremented each time a byte is sent over the air. This operation stops once the number of bytes sent equals the payloadlength parameter as defined in function SetPacketParam(). 8.4 Using the Data buffer Both, rxBaseAddress and txBaseAddress are set using the command SetBufferBaseAddress(). By default rxBaseAddress and txBaseAddress are initialized at address 0x00. Due to the contiguous nature of the data buffer, the base addresses for Tx and Rx are fully configurable across the 256-byte memory area. Each pointer can be set independently anywhere within the buffer. To exploit the maximum data buffer size in transmit or receive mode, the whole data buffer can be used in each mode by setting the base addresses txBaseAddress and rxBaseAddress at the bottom of the memory (0x00). It is possible to keep data value in Sleep mode by maintaining the data buffer under retention. However the pointer locations will be lost. In order to retrieve data from sleep retention the user must use default value for base address (for example 0x00 for Rx and 0x80 for Tx) or store PayloadLengthRx and RxStartBufferPointer before going to Sleep mode. The data buffer is acceded via SPI or UART using the command WriteBuffer() and ReadBuffer(). In this function the parameter offset defines the address pointer of the first data to be written or read. Offset zero defines the first position of the data buffer. Before any read or write operation it is hence necessary to initialize this offset to the corresponding beginning of the buffer. Upon reading or writing to the data buffer the address pointer will then increment automatically. Two possibilities exist to obtain the offset value: • The command GetRxBufferStatus returns rxBaseAddress and PayloadLengthRx that can be used to read-back the packet received in variable packet length mode. • Use the rxBaseAddress value and the known packet length can be used in fixed packet length mode. Important Note: All received data will be written to the data buffer even if the CRC is invalid, permitting user-defined post processing of corrupted data. When receiving, if the packet size exceeds the buffer memory allocated for the Rx, it will overwrite the transmit portion of the data buffer. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 58 of 158 Semtech 9. Digital Interface and Control Analog Front End & Data Conversion LORA Modem & Ranging ADC LNA Protocol Engine FLRC Modem Match PA SPI or UART PLL FSK Modem OSC DC-DC Data Buffer LDO Figure 9-1: Transceiver Block Diagram, Digital Interface Highlighted The transceiver is controlled via a serial interface (SPI or UART) and a set of general purpose input/output (DIOs). The transceiver uses a Protocol Engine to handle communication and transceiver control (mode switching, API etc...). Through SPI or UART the application sends commands to the internal processor or accesses directly the data memory space. All registers can be accessed by SPI or UART. 9.1 BUSY Pin Communication In all communications the BUSY Pin is used to indicate, when low, that the transceiver is ready for new command. See Section 2. "Pin Connections" on page 17. 9.2 Interface Detection At power-up both interfaces are enabled until the first one receives a valid transaction, this disables the unused interface. To allow reception by the SX1280 UART, RTSN needs to be driven low. However, since it is shared with SCK, initially the pin 18 is driven low with a high impedance driver. If the UART interface is detected, pin 18 is driven directly by the on-chip UART; otherwise the pin is configured as an input pin with a pull-down. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 59 of 158 Semtech 9.3 SPI Interface The SPI interface gives access to the configuration register and API commands via a synchronous full-duplex frame corresponding to CPOL = 0 and CPHA = 0 in Motorola/Freescale nomenclature. Only the slave side is implemented. Meaning that MOSI is generated by the master on the falling edge of SCK and is sampled by the slave (i.e. this SPI interface) on the rising edge of SCK. MISO is generated by the slave on the falling edge of SCK. Both write and reads operations are initiated by sending the corresponding opcode, then followed by 2 address bytes. Note that it is possible to read/write several bytes. The NSS pin is driven low at the beginning of the frame and high after the data byte. A transfer is always started by the NSS pin going low. MISO is high impedance when NSS is high. The SPI runs on the external SCK clock to allow high speed up to 18 MHz. The host terminates an SPI transaction by raising the NSS signal, it does not explicitly send the command length as a parameter. The host must not raise NSS within the bytes of a transaction. If the host sends a command requiring parameters, all parameters must be sent before raising NSS. If not, the transceiver will use unknown values for the missing parameters. 9.3.1 SPI Timing The following specifications are given for the typical operating conditions of VBAT_IO = VBAT = 3.3 V, temperature = 25 °C, crystal oscillator frequency = 52 MHz. All timings are given in next table for Max load cap of 10 pF. Table 9-1: SPI Timing Requirements Symbol Description Minimum Typical Maximum Unit t1 NSS falling edge to SCK setup time 25 - - ns t2 SCK period 55 - - ns t3 SCK high time 25 - - ns t4 MOSI to SCK hold time 5 - - ns t5 MOSI to SCK setup time 5 - - ns t6 NSS falling to MISO delay 0 - 15 ns t7 SCK falling to MISO delay 0 - 15 ns t8 SCK to NSS rising edge hold time 25 - - ns t9 NSS high time 100 - - ns t10 NSS falling edge to SCK setup time when switching from Sleep to STDBY_RC mode 125 - - μs SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 60 of 158 Semtech 9.3.2 SPI Timing When the Transceiver is in Active Mode The transceiver is considered to be in active mode when not in Sleep mode. In active mode the transceiver can immediately process standard SPI commands i.e. there is no extra delay needed at the first SPI transaction. The main reason is that, contrary to the behavior when in sleep mode, the transceiver does not have to go through the start-up process. Figure 9-2: SPI Timing Diagram SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 61 of 158 Semtech 9.3.3 SPI Timing When the Transceiver Leaves Sleep Mode When in Sleep mode the transceiver can be awakened by applying a falling edge to NSS. Upon this falling edge, all necessary internal regulators are switched ON; the transceiver must complete its initialization before being able to accept the first SPI command. The delay between the falling edge of NSS and the first rising edge of SCK must take into account the transceiver initialization. There are two methods to account for the initialization time. The first method, presented below, shows that following the wake-up, falling edge transition of NSS the transceiver waits a minimum of 125 us before commencing SPI communication to ensure that the wake-up process is complete. Figure 9-3: SPI Wake-UpTiming Transition The alternative method, shown in the following figure, sees a pulse (tPulse) which must be of at least 2 us duration sent on the NSS line. Following this, the BUSY signal will go to zero once the wake-up process is complete. This falling edge can then be used to initiate the first SPI communication on the bus. Note that in both cases that output on MISO will not be valid as the digital interface detection process will be running. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 62 of 158 Semtech Figure 9-4: SPI NSS Pulse Timing Transition In both cases the busy signal mapped on BUSY pin is set high, indicating to the host that the transceiver is not able to accept a new command. Once the transceiver is in STDBY_RC mode, the busy signal goes low and the host can start sending a command. Note: This is also true for startup at power on or after hard reset. The values for the SPI timings are visible in Section "The values for the SPI timings are visible in ." on page 63. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 63 of 158 Semtech 9.4 UART Interface 9.4.1 Default UART Settings The transceiver UART supports the following settings: • Baud rates: 812.49 k, 460.6 k, 115.2 k, 57.6 k, 38.4 k, 19.2 k, 9.6k • RTS/CTS flow control • Parity control: none, odd, even • 8 bit words • 1, 2 stop bits • Rx full, Tx empty, Error (parity, no stop bit) interrupts. Initially the UART is configured to operate at 115.2 kbps with 1 stop bit, even parity, CTS flow control and with all communication arriving Least Significant Bit (LSB) first. At start-up the CSTN must be driven low to initiate communication. Following device reset it is necessary to flush information received on the UART Rx line before performing the first read operation. Other compatible UART communication settings may then be configured. In a UART transaction, the host must provide the command length. The device starts processing the transactions as soon as the required bytes have been received. Subsequent bytes are treated as belonging to a new transaction. 9.4.2 Setting the UART Speed Understanding that the first communication with the radio must be made at the default UART speed of 115.2 kbps, it is possible to change the interface clock speed using the SetUartSpeed. Please see Section 11.2 "SetUartSpeed Command" on page 72 for more details. 9.5 Pin Sharing The pins between SPI and UART are shared in the following way: • NSS (IN) / CTSN (IN) • SCK (IN) / RTSN (OUT) • MOSI (IN) / RX (IN) • MISO (OUT) / TX (OUT) 9.6 Multi-Purpose Digital Input/Output (DIO) The transceiver provides 3 DIOs that can be configured as an interrupt. The BUSY pin may be used as an interrupt by the host and is always an output. The busy interrupt is asserted low when the current command has been processed and the device is ready to accept a new one. Additionally any of the 3 DIOs can be selected as an external interrupt source for the transceiver. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 64 of 158 Semtech Note: Any of the 3 DIOs can be mapped to any interrupt source from the transceiver using the SetDioIrqParams() command. For full details please see Section 11.9.1 "SetDioIrqParams" on page 96. When the application receives an interrupt it can determine the source by reading the device IRQ register. The interrupt can be cleared using the ClearIrq() command. When the SPI interface is used, the status is sent on every transaction that does not require data to be sent. When using the UART interface the status can be retrieved via GetIrqStatus() command. 9.7 Transceiver Initialization on a Shared SPI Bus Upon initial power up (or power-on-reset) of the SX1280, the radio determines which digital serial bus (SPI or UART) will used based upon detection of the first communication received over the digital bus. To an SX1280 to a shared Serial Peripheral Interface (SPI) bus it is necessary to reset each radio prior to starting the first SPI communication with that device after power-up. This is illustrated below. In this example, a suitable communication start-up sequence would be as follows: 1. Power-on or Power-on-Reset 2. SPI communication with Sensor 3. RESET SX1280 A 4. SPI Communication with SX1280 A 5. RESET SX1280 B 6. SPI Communication with SX1280 B SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 65 of 158 Semtech SX1280 A NSS_A RESET_A NSS_A RESET_A SCK MOSI MISO SCK MISO MOSI MCU NSS_B RESET_B NSS_C RESET_C SX1280 B SCK MISO MOSI NSS_B RESET_B Sensor C SCK MISO MOSI NSS_B RESET_B Figure 9-5: Multiple Radios Sharing an SPI Bus With a Sensor SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 66 of 158 Semtech 10. Operational Modes The transceiver features six operating modes, the analog front end and digital blocks that are enabled in each operating mode are explained in the following table: Table 10-1: SX1280 Operating Modes Mode Enabled Blocks SLEEP Optional registers, backup regulator, RC64K oscillator, data buffer, data RAM STDBY_RC Top regulator (LDO), RC13M oscillator STDBY_XOSC Top regulator (DC-DC), RC13M oscillator, XOSC FS Frequency synthesizer at Tx frequency Tx Frequency synthesizer and transmitter, Modem Rx Frequency synthesizer and receiver, Modem 10.1 Startup At power-up, the transceiver enters its start-up state. The BUSY pin is set to high, indicating that the transceiver is busy and cannot accept a command. When the digital voltage and RC clock are available, the transceiver can boot up and initiate the calibration phase which consists of: • Calibration of the RC13 MHz with help of the52 MHz crystal. • Calibration of the RC 64K with the help of the 52 MHz crystal. • Calibration of the PLL modulation path • Calibration of the ADC Once the calibration has terminated, the transceiver enters STDBY_RC mode. The transceiver is now ready and the BUSY pin goes low, indicating that the device is ready to accept a command from the host. All results from calibration are stored in the data memory. When the transceiver wakes up from a Sleep mode and the data memory content is preserved, the calibration data is retrieved from memory without repeating the complete procedure. 10.2 Sleep Mode In this mode only Start-up and Sleep Controller (SCC) block and optionally RC32K and timers are running, memories may be placed under retention. The transceiver may enter in this mode from STDBY_RC state and can leave the Sleep Mode if the NSS pin (19) is driven low. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 67 of 158 Semtech 10.3 Standby Mode In Standby mode the host should configure the transceiver before going to either Rx or Tx modes. By default in this state, the system is clocked by the 13 MHz RC oscillator to reduce power consumption. However if the application is time critical, the XOSC block can be turned or left ON. Crystal oscillator (STDBY_XOSC) or 13 MHz RC oscillator (STDBY_RC) selection in STDBY mode is determined by mode parameter in command SetStandby(oscillatorMode) command. The DC-DC supply regulation is automatically powered in STDBY_XOSC mode. 10.4 Frequency Synthesis (FS) Mode In FS mode, PLL and related regulators are switched ON. The BUSY pin goes low as soon as the PLL is locked. The radio may be requested to remain in this mode by using the SetFs() command. Since the transceiver uses a low IF architecture, the Rx and Tx frequencies are different. The Rx frequency is equal to Tx frequency minus the intermediate frequency (IF) offset (1.3 MHz by default). In FS mode the frequency to which the PLL is tuned corresponds to the transmit frequency. 10.5 Receive (Rx) Mode In Rx mode the LNA, MIXER, PLL and selected modem (LoRa/FSK/FLRC) are turned ON. In continuous mode the device remains in Rx mode and looks for incoming packets until the host requests a different mode. In single mode the device returns automatically to STDBY_RC mode. The transition to receive mode is made by issuing the SetRx(periodBase, periodBaseCount) command. The periodBase (oscillator timebase) and periodBaseCount (number of clock ticks) specifies the time-out upon which receive mode will be exited to STDBY_RC mode. The process of periodic reception can be fully automated in the transceiver. This process and the processing specific to each modulation format are described in Section 14.1.3 "Rx Setting and Operations" on page 111. 10.6 Transmit (Tx) Mode In Tx mode, after ramp-up the Power-Amplifier (PA) transmits the Tx packet. The device returns automatically to STDBY_RC after transmitting the packet. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 68 of 158 Semtech 10.7 Transceiver Circuit Modes Graphical Illustration All of the device operating modes and the states through which each mode selection transitions is shown in the figure below: reset POWER ON or RESET RTC or NSS (UART & SPI Operation) startup sleep SetStanby() SetFs() STDBY FS SetRx() Rx SetTx() Tx Figure 10-1: Transceiver Circuit Modes SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 69 of 158 Semtech 10.8 Active Mode Switching Time At each transaction with the transceiver (API command, register read/write operation or mode switching) the BUSY pin is set to high during the transaction and while the transceiver is processing the command (API command and mode switching only). There is a bief 217 ns delay between the falling edge of NSS and the rising edge of BUSY. The BUSY pin is set back to zero once the transceiver is ready for new commands or has reached a stable mode. In the following figure, the switching time is defined as the time between the rising edge of the NSS ending the SPI transaction and the falling edge of BUSY. Figure 10-2: Switching Time Definition in Active Mode Table 10-2: Switching Time (TswMode) for all Possible Transitions Transition TswMode Typical Value [μs] SLEEP to STDBY_RC 1200 no data retention SLEEP to STDBY_RC 130 with data retention STDBY_RC to STDBY_XOSC 40 STDBY_RC to FS 55 STDBY_RC to Rx 85 STDBY_RC to Tx 80 STDBY_XOSC to FS 54 STDBY_XOSC to Tx 54 STDBY_XOSC to Rx 68 FS to Rx 34 FS to Tx 27 Rx to FS 13 Rx to Tx 39 Tx to FS 31 Tx to Rx 60 In FS, BUSY pin will go low when the PLL is locked. In Rx, BUSY pin will go low as soon as the Rx is up and ready to receive data. In Tx, BUSY pin will go low when the PA has ramp-up and transmission of preamble starts. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 70 of 158 Semtech 11. Host Controller Interface Through SPI or UART interface, the host can issue commands to the transceiver or access the data memory space to directly retrieve or write data. In normal operation a reduced number of direct data write operations is required except for data buffer. The user interacts with the transceiver through an API (instruction set). The transceiver uses a BUSY pin to indicate the status of the transceiver and its ability to receive a command while it is completing its internal processing. Prior to the host transmitting a command, it is thus necessary to check the status of the BUSY pin to ensure that the transceiver is in a state to process it. Two types of transactions are supported: • Configuration transaction: provides to the host a direct register access i.e. it is used for writing or reading the transceiver configuration registers or the data buffer. • Command transaction: allows simple access to complex operations such as packet transmission / reception or mode switching. 11.1 Command Structure In the case of a command that does not pass any parameters, the host sends only the opcode (1 byte) on both SPI and UART interface. In the case of a command that requires parameters: • For SPI transfer the opcode byte is followed immediately by the parameter bytes with NSS rising edge terminating the command. Table 11-1: SPI interface Command Sequence • Byte 0 [1:n] Data from host opcode parameters Data to host status status For UART transfer the opcode byte is followed by the length byte (i.e. the number of parameter bytes) then by the parameter bytes. Table 11-2: UART Interface Command Sequence • Byte 0 1 [2:n] Data from host opcode length parameters For UART buffer write operation, after having sent the LSB of the address, the host must send a byte defining the number of data bytes that will be transmitted. That number of data bytes must then be transmitted. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 71 of 158 Semtech • For UART buffer read operation, after having sent the LSB of the address, the host must send a byte defining the number of data bytes that will be received. The transceiver will then transmit that number of bytes to the host. • For UART direct configuration register access, after having sent the opcode and the address, the UART has to send the number of bytes to be read/written. 11.2 SetUartSpeed Command Once communication has been initiated by UART at 115.2 kbps, the SetUartSpeed command can be used to modify the connection data rate. This is expressed as the ratio of a divider ratio and the digital clock speed: UartDividerRatio = (Baud Rate * 2^20) / fClk where Baud Rate is the desired communication rate, from the list of valid data rates and UartDividerRatio is the divider ratio needed to configure that UART baud rate for the radio. Once configured, all ensuing communication will be at the new rate. Table 11-3: SetUartSpeed Data Transfer (UART only) Byte 0 1 2-3 Data from host Opcode = 0x9D Size = 0x02 UartDividerRatio Table 11-4: Divider Ratios to Configure the UART Interface Speed Baud Rate UartDividerRatio [decimal] UartDividerRatio [hexadecimal] 2400 194 C2 4800 387 183 9600 774 306 14400 1161 489 19200 1549 60D 38400 3097 C19 57600 4646 1226 115200 9292 244C 460600 37152 9120 812490 65535 FFFF 11.3 GetStatus Command The host can retrieve the transceiver status directly through the GetStatus() command: this command can be issued at any time as long as it is not the very first command send over the interface. For the SPI interface, the device returns the status on the same transaction; in the case of a UART frame, the status is returned by a write transaction following the command. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 72 of 158 Semtech When using the SPI interface, the GetStatus() command is not strictly necessary since the device returns status information also on command bytes. The status byte returned is described in the following table: Table 11-5: Status Byte Definition 7:5 4:2 1 0 Circuit mode Command status Reserved Reserved 0x0: Reserved 0x0: Reserved 0x1: Reserved 0x1: Transceiver has successfully processed the command1 0x2: STDBY_RC 0x2: Data are available to host2 0x3: STDBY_XOSC 0x3: Command time-out3 - - 0x4: FS 0x4: Command processing error4 0x5: Rx 0x5: Failure to execute command5 0x6: Tx 0x6: Command Tx done6 1. The command has been terminated correctly 2. A packet has been successfully received and data can be retrieved 3. A transaction from the host took too long to complete and triggered an internal watchdog. The watchdog mechanism can be disabled by the host, it is meant to prevent a dead-lock situation. In this case host should resend the command. 4. The transceiver was unable to process command either because of an invalid opcode or because an incorrect number of parameters has been provided. 5. The command was successfully processed, however the transceiver could not execute the command; for instance it was unable to enter the specified device mode or send the requested data, 6. The transmission of the current packet has terminated The SPI transaction for GetStatus() command is given in Table 11-6, and the UART transaction on Table 11-7. Table 11-6: GetStatus Data Transfer (SPI) Byte 0 Data from host Opcode = 0xC0 Data to host status Example of an SPI command binary pattern to get the status of the transceiver: 0xC0 Table 11-7: GetStatus Data Transfer (UART) Byte 0 1 Data from host Opcode = 0xC0 - Data to host - status SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 73 of 158 Semtech 11.4 Register Access Operations 11.4.1 WriteRegister Command The command WriteRegister() writes a block of bytes in a data memory space starting at a specific address. The address is auto incremented after each data byte so that data is stored in contiguous memory locations. The SPI data transfer is described on Table 11-8 and UART data transfer is described on Table 11-9. Table 11-8: WriteRegister Data Transfer (SPI) Byte 0 1 2 3 4 ... n+3 Data from host Opcode = 0x18 address[15:8] address[7:0] data@address data@address+1 ... data@address+n Data to host status status status status status ... status Example1 0x18 0x08 0x01 0xA1 0x62 ... 0x7E 1. Example SPI command binary pattern to write the n-2 bytes of data [0xA1, 0x62, ... 0x7E] from register address 0x0801 Table 11-9: WriteRegister Data Transfer (UART) Byte 0 1 2 3 4 5 ... n+4 Host UART Tx Opcode = 0x18 address[15:8] address[7:0] length = (n) data@address data@address+1 ... data@address+n SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 74 of 158 Semtech 11.4.2 ReadRegister Command The command ReadRegister() reads a block of data starting at a given address. The address is auto incremented after each byte. The SPI data transfer is described in Table 11-10, and the UART data transfer in Table 11-11. In UART case, the number of data to be read is provided by length parameter. Note: When using SPI, the host has to send a NOP after sending the 2 bytes of address to start receiving data bytes on the next NOP sent. Table 11-10: ReadRegister Data Transfer (SPI) Byte 0 1 2 3 4 5 ... n+4 Data from host Opcode = 0x19 address[15:8] address[7:0] NOP NOP NOP ... NOP Data to host status status status status data@address data@address+1 ... data@address+n Example1 0x19 0x08 0x01 0x00 0x00 0x00 - 0x00 1. Example SPI command binary pattern to read the n-3 registers from 0x0801 Table 11-11: ReadRegister Data Transfer (UART) Byte 0 1 2 3 4 5 ... n+4 Host UART Tx Opcode = 0x19 address[15:8] address[7:0] length --- ---- ... ---- Chip UART Tx --- ---- --- ---- data@address data@address+1 ... data@address+n 11.5 Data Buffer Operations 11.5.1 WriteBuffer Command This function is used to write the data payload to be transmitted. The address is auto-incremented, when the address exceeds 255 it wraps back to 0 due to the circular nature of data buffer. The address starts from the offset given as a parameter of the function. Table 11-12 describes SPI data transfer, and Table 11-13 describes UART data transfer. Table 11-12: WriteBuffer SPI Data Transfer Byte 0 1 2 3 ... n+2 Data from host Opcode = 0x1A offset data@offset data@offset+1 ... data@offset+n Data to host status status status status ... status Example1 0x1A 0x20 0x2C 0xF5 - 0x82 1. Example SPI command binary pattern to write the (n-2)-bytes payload [0x2C, 0xF5, 0x82] in the buffer at offset 0x20 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 75 of 158 Semtech Table 11-13: WriteBuffer UART Data Transfer Byte 0 1 2 3 4 ... n+3 Host UART Tx Opcode =0x1A offset length = n data@address data@address+1 ... data@address+n Chip UART Tx --- ---- --- --- ---- --- --- 11.5.2 ReadBuffer This function allows reading (n-3) bytes of payload received starting at offset. Table 11-14: ReadBuffer SPI Data Transfer Byte 0 1 2 3 4 ... n+3 Data from host Opcode = 0x1B offset NOP NOP NOP ... NOP Data to host status status status data@offset data@offset+1 ... data@offset+n Example1 0x1B 0x20 0x00 0x00 0x00 - 0x00 1. Example SPI command binary pattern to read the (n-3)-bytes payload in the buffer at offset 0x20 Table 11-15: ReadBuffer UART Data Transfer Byte 0 1 2 3 4 ... n+3 Host UART Tx opcode = 0x1B offset length --- ---- ... NOP Device UART Tx --- ---- --- data@offset data@offset+1 ... data@offset+n SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 76 of 158 Semtech 11.6 Radio Operation Modes This chapter describes the command set available for the transceiver. The transaction is given for SPI only but the same commands are available when using UART. 11.6.1 SetSleep The SetSleep() command is used to set the transceiver to Sleep mode with the lowest current consumption possible. After rising edge of NSS, all blocks are switched OFF except backup regulator if needed and the blocks specified in sleepConfig parameter. Table 11-16: SetSleep SPI Data Transfer Byte 0 1 Data from host Opcode = 0x84 sleepConfig Example1 0x84 0x01 1. Example SPI command binary pattern to activate sleep mode with only data RAM retention The sleepConfig argument is defined as: Table 11-17: Sleep Mode Definition sleepConfig[7:4] sleepConfig[1] 1: Data buffer in retention mode Unused sleepConfig[0] 0: Data RAM is flushed during Sleep Mode 1: Data RAM in retention mode The transceiver will wake from SLEEP mode to STDBY_RC upon the detection of a rising edge on the NSS. When placing the transceiver in SLEEP mode there are two main levels of memory retention possible: If sleepConfig[0] is set, then a subset of the SX1280 configuration will be saved to volatile memory. It is important  to note that not all instructions will be retained. The parameters that are stored are: SetPacketType() SetModulationParams()  SetPacketParams() SetRfFrequency() SetDioIrqParams() SetCadParams() SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 77 of 158 Semtech (Please consult Section 13 for the use of these functions). In addition to storing some of the configuration  information, the principal benefit of the retention is the storage of internal, device specific calibration values. This  allows an order of magnitude improvement in typical SLEEP to STDBY_RC mode transition times (see Section  10.8). Data RAM retention is particularly suited to applications that require fast transition into RECEIVE mode  from SLEEP. If sleepConfig[1] is set, then the contents of the data buffer is stored during SLEEP mode. 11.6.2 SetStandby The command SetStandby() is used to set the device in either STDBY_RC or STDBY_XOSC mode which are intermediate levels of power consumption. In this Standby mode, the transceiver may be configured for future RF operations. After power on or application of a reset, NSS or RTC wake-up the transceiver will enter in STDBY_RC mode running with a 13 MHz RC clock. Table 11-18: SetStandby SPI Data Transfer Byte 0 1 Data from host Opcode = 0x80 StandbyConfig Example1 0x80 0x00 1. Example SPI command binary pattern to activate standby mode running on RC 13 MHz Table 11-19: SetStandby UART Data Transfer Byte 0 1 2 Data from host Opcode = 0x80 0x01 StandbyConfig The StandbyConfig byte definition is given in next table: Table 11-20: StandbyConfig Definition StandbyConfig Value Description STDBY_RC 0 Device running on RC 13MHz, set STDBY_RC mode STDBY_XOSC 1 Device running on XTAL 52MHz, set STDBY_XOSC mode 11.6.3 SetFs Command SetFs() is used to set the device in Frequency Synthesizer mode where the PLL is locked to the carrier frequency. This mode is used for test purposes of the PLL and can be considered as an intermediate mode when going from STDBY_RC SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 78 of 158 Semtech mode to Tx mode or to Rx mode. Data transfer for this command is the same for SPI and UART. In normal operation of the transceiver, the user does not normally need to use FS mode. Table 11-21: SetFs Data Transfer Byte 0 Data from host Opcode = 0xC1 Example1 0xC1 1. Example SPI command binary pattern to activate Frequency Synthesis mode 11.6.4 SetTx The command SetTx() sets the device in Transmit mode. Clear IRQ status before using this command see Section 11.9.3 "ClearIrqStatus" on page 97. Table 11-22: SetTx SPI Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x83 periodBase periodBaseCount[15:8] periodBaseCount[7:0] Example1 0x83 0x00 0x00 0x00 1. Example SPI command binary pattern to activate Transmit mode with no timeout, stopping Tx mode after first packet sent (aka Single Mode Tx) Table 11-23: SetTx UART Data Transfer Byte 0 1 2 3 4 Data from host Opcode = 0x83 0x03 periodBase periodBaseCount[15:8] periodBaseCount[7:0] Starting from STDBY_RC mode the oscillator is switched ON followed by the PLL, then the PA (Power Amplifier) is switched ON and the PA regulator starts ramping according to the ramp-up time defined by SetTxParam() command. Once the ramp-up is complete the packet handling starts the packet transmission. Once the last bit of the packet has been sent, the PA regulator is ramped down, the PA is switched OFF, the transceiver goes back to STDBY_RC mode and an IRQ TxDone is generated. A TIMEOUT IRQ is generated if the transmission takes longer than programmed timeout value. The transceiver goes back to STDBY_RC mode after a TIMEOUT IRQ or a TxDone IRQ. The time-out duration is given by the formula: Time-out duration = periodBase * periodBaseCount Where periodBase is the step of the RTC defined in the next table. Table 11-24: SetTx Time-out Definition. periodBase Time-out step 0x00 15.625 μs 0x01 62.5 μs SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 79 of 158 Semtech Table 11-24: SetTx Time-out Definition. periodBase Time-out step 0x02 1 ms 0x03 4 ms periodBaseCount is a 16-bit parameter defining the number of steps used during time-out as defined in the following table: Table 11-25: SetTx Time-out Duration periodBaseCount[15:0] Time-out duration 0x0000 No time-out, Tx Single mode, the device will stay in Tx Mode until the packet is transmitted and returns in STDBY_RC mode upon completion. Others Time-out active, the device remains in Tx mode, it returns automatically to STDBY_RC mode on timer end-of-count or when a packet has been transmitted. 11.6.5 SetRx The command SetRx() sets the device in Receiver mode. The IRQ status should be cleared prior to using this command, see Section 11.9.3 "ClearIrqStatus" on page 97. Table 11-26: SetRx SPI Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x82 periodBase periodBaseCount[15:8] periodBaseCount[7:0] Example1 0x82 0x03 0x00 0xFA 1. Example SPI command binary pattern to activate Receive mode with timeout after 1 second, with periodBase of 4 ms and a periodCount of 250, i.e. 0x00FA Table 11-27: SetRx UART Data Transfer Byte 0 1 2 3 4 Data from host Opcode = 0x82 0x03 periodBase periodBaseCount[15:8] periodBaseCount[7:0] This command sets the transceiver in Rx mode, waiting for the reception of one or several packets. The Receiver mode operates with a time-out to provide maximum flexibility to the end user. The parameters for time-out duration are: Time-out duration = periodBase * periodBaseCount Where periodBase is the step of the RTC as defined in Table 11-24. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 80 of 158 Semtech periodBaseCount is the number of steps used during time-out as defined in the following table: Table 11-28: SetRx Time-out Duration TickNum(15:0) Time-out duration 0x0000 No time-out. Rx Single mode. The device will stay in Rx mode until a reception occurs and the devices return in STDBY_RC mode upon completion 0xFFFF Rx Continuous mode. The device remains in Rx mode until the host sends a command to change the operation mode. The device can receive several packets. Each time a packet is received, a “packet received” indication is given to the host and the device will continue to search for a new packet. Others Time-out active. The device remains in Rx mode, it returns automatically to STDBY_RC mode on timer end-of-count or when a packet has been received. As soon as a packet is detected, the timer is automatically disabled to allow complete reception of the packet. 11.6.6 SetRxDutyCycle This command sets the transceiver in sniff mode, so that it regularly looks for new packets (duty cycled operation). Table 11-29: Duty Cycled Operation SPI Data Transfer Byte 0 1 2 3 Data from host Opcode= 0x94 PeriodBase rxPeriodBase Count Example1 0x94 0x03 [15:8] 0x00 rxPeriodBase Count[7:0] 0xAF 5 6 sleepPeriodBase Count sleepPeriodBase Count [15:8] [7:0] 0x00 0xFA 1. Example SPI command binary pattern to activate Receive Duty Cycle mode with 700 ms Rx window and 1 second sleep (with periodBase of 4 ms, rxPeriodBaseCount at 175 ie. 0x00AF, sleepPeriodBaseCount at 250 ie. 0x00FA) Table 11-30: Duty Cycled Operation UART Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x94 0x05 PeriodBase rxPeriodBase Count [15:8] 4 rxPeriodBase Count[7:0] 6 7 sleepPeriodBase Count sleepPeriodBase Count [15:8] [7:0] Once this command is sent in STDBY_RC mode, the context (Rx configuration) is saved into the data RAM and the transceiver starts a loop defined by the following steps: • Enter Rx and listen for a packet for a period of time defined by PeriodBase and rxPeriodBaseCount. • The transceiver looks for a preamble and, if detected, the transceiver looks for a Sync Word and payload. • If no packet is received during Rx window, the transceiver goes in Sleep mode (with context saved) for a period of time defined by PeriodBase and sleepPeriodBaseCount. • At the end of the Sleep window, the transceiver leaves the Sleep mode, restores the context and enters the Rx mode then listens for a packet during Rx window. At any time, the host can stop the procedure.The loop is terminated if: SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 81 of 158 Semtech  A packet is detected during the Rx window, the transceiver interrupts the host via the RxDone flag and returns to STDBY_RC mode.  The host issues a SetStandby() command during the Rx window (within Sleep the window device is unable to receive commands). Note:  To use the RxDone interrupt, you have to enable the corresponding IRQ prior to enter Duty cycled operation. To enable the RxDone IRQ via the corresponding SetDioIrqParams() in Section 11.9.1 "SetDioIrqParams" on page 96. The Sleep mode duration is defined by: Sleep Duration = PeriodBase * sleepPeriodBaseCount The Rx mode duration is defined by Rx Duration = PeriodBase * rxPeriodBaseCount where PeriodBase is defined as periodBase in Table 11-24. rxPeriodBaseCount and sleepPeriodBaseCount are 16-bit parameters defining the number of steps used to define the Rx duration and Sleep durations. Some specific values for rxPeriodBaseCount are given in Table 11-31. Table 11-31: Rx Duration Definition. rxPeriodBaseCount[15:0] Time-out duration 0x0000 The transceiver waits until a packet is found. Once found, the transceiver goes to STDBY_RC mode after sending an RxDone IRQ to the host. Others The device will stay in Rx Mode for Rx duration period and then return to Sleep Mode for Sleep duration. Note: The command SetLongPreamble must be issued prior to SetRxDutyCycle. 11.6.7 SetLongPreamble The command (opcode 0x98) sets the transceiver into Long Preamble mode, and can only be used with either the LoRa® mode and GFSK mode. In this mode, the behavior of the commands SetTx, SetRx and SetRxDutyCycle is modified as: • In GFSK only, the SetTx parameters defines the duration of the packet preamble. (The arguments do not define a timeout so no TxTimeout interrupt is generated in GFSK mode). • In GFSK only with LongPreamble mode, the preamble detection mode is activated. The command SetRx can then generate an interrupt for Preamble detection. • In GFSK and LoRa®, the behavior of RxDutyCycle is modified so that if a preamble is detected, the Rx window is extended by SleepPeriod + 2 * RxPeriod. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 82 of 158 Semtech Table 11-32: SetLongPreamble Data Transfer Byte 0 1 Data from host Opcode = 0x9B Enable Example1 0x9B 0x01 1. Example SPI command binary pattern to activate Long Preamble mode 11.6.8 SetCAD The command SetCAD() (Channel Activity Detection) can be used only in LoRa® packet type. The Channel Activity Detection is a LoRa® specific mode of operation where the device searches for a LoRa® signal. After search has completed, the device returns to STDBY_RC mode. The length of the search is configured via SetCadParams() command. At the end of search period the device always sends the CadDone IRQ. If a valid signal has been detected it also generates the CadDetected IRQ. This mode of operation is especially useful in all the applications requiring Listen before Talk. The UART data transfer and SPI data transfer are the same. Table 11-33: SetCAD Data Transfer Byte 0 Data from host Opcode = 0xC5 Example1 0xC5 1. Example SPI command binary pattern to activate Channel Activity Detection mode 11.6.9 SetTxContinuousWave The command SetTxContinuousWave() is a test command to generate a Continuous Wave (RF tone) at a selected frequency and output power. The device remains in Tx Continuous Wave until the host sends a mode configuration command. This command is available for all packet types. The UART data transfer and SPI data transfer are the same. Table 11-34: SetTxContinuousWave Data Transfer Byte 0 Data from host Opcode = 0xD1 Example1 0xD1 1. Example SPI command binary pattern to activate Continuous Wave Transmit mode 11.6.10 SetTxContinuousPreamble The command SetTxContinuousPreamble() is a test command to generate an infinite sequence of alternating ‘0’s and ‘1’s in GFSK modulation and symbol 0 in LoRa®. The device remains in transmit until the host sends a mode configuration command. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 83 of 158 Semtech The UART data transfer and SPI data transfer are the same. Table 11-35: SetTxContinuousPreamble Data Transfer Byte 0 Data from host Opcode = 0xD2 Example1 0xD2 1. Example SPI command binary pattern to activate Continuous Preamble Transmit mode A summary is given below of the preamble functions available for each mode: Modem SetTxContinuousPreamble SetLongPreamble PacketParam Maximum Preamble Length GFSK Yes Yes 32 bits BLE No1 No 32 bits FLRC No2 No 32 bits LoRa Yes Yes 65535 symbols 1. Long preamble can be synthesised using FSK mode configured at 1 Mbps, Modulation Index = 0.5 and BT = 0.5 2. Can be approximated in firmware using a buffer fill of 255 bytes of 0x55, understanding that the RF envelope will ramp up and down briefly at the beginning and end of each packet sequence. 11.6.11 SetAutoTx BLE requires the transceiver to be able to send back a response 150 μs after a packet reception. This is carried out by sending the command SetAutoTx() which allows the transceiver to send a packet at a user programmable time (time) after the end of a packet reception. SetAutoTx() must be issued in STDBY_RC mode. The data transfer of SetAutoTx() is described in Table 11-36. Table 11-36: SetAutoTx SPI Data Transfer Byte 0 1 2 Data from host Opcode = 0x98 time[15:8] time[7:0] Example1 0x98 0x00 0x5C 1. Example SPI command binary pattern to activate automatic Transmit mode after 125 us (ie. 92 us after offset, 0x5C) Table 11-37: SetAutoTx UART Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x98 0x02 time[15:8] time[7:0] SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 84 of 158 Semtech time is expressed in μs. The delay between the packet reception end and the next packet transmission start is defined by: Tx Delay = time + Offset Here Offset is a time needed for the transceiver to switch modes and is equal to 33 μs. When this command is issued, each time the transceiver goes in Rx mode, once it has received a packet, it automatically switches to Tx and sends a packet in a predefined time TxDelay. To to resume normal mode,e.g going to STDBY_RC after reception, user must issue the command SetAutoTx with 0x00 as the time argument. 11.6.12 SetAutoFs This feature modifies the chip behavior so that the state following a Rx or Tx operation is FS and not STDBY (see Section 10.7 "Transceiver Circuit Modes Graphical Illustration" on page 69). This feature is to be used to reduce the switching time between consecutive Rx and/or Tx operations (see Table 10-2: Switching Time (TswMode) for all Possible Transitions). • To activate the AutoFs feature, use the command SetAutoFs with argument enable. • To deactivate the AutoFs feature, use the command SetAutoFs with disable. Table 11-38: SetAutoFs SPI Data Transfer Byte 0 1 Data from host Opcode = 0x9E enable=0x01, disable=0x00 Example1 0x9E 0x01 1. Example SPI command binary pattern to activate automatic Frequency Synthesis mode after receive or transmit operation Table 11-39: SetAutoFs UART Data Transfer Byte 0 1 2 Data from host Opcode = 0x9E 0x1 enable 11.7 Radio Configuration 11.7.1 SetPacketType The command SetPacketType() sets the transceiver radio frame out of a choice of 5 different packet types. Despite some packet types using the same physical modem, they do not all share the same parameters. Note: The command SetPacketType() must be the first in a radio configuration sequence. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 85 of 158 Semtech Table 11-40: SetPacketType SPI Data Transfer Byte 0 1 Data from host Opcode = 0x8A packetType Example1 0x8A 0x01 1. Example SPI command binary pattern to set packet type to LoRa® Table 11-41: SetPacketType UART Data Transfer Byte 0 1 2 Data from host Opcode = 0x8A 0x01 packetType The parameter for this command is defined in Table 11-42. Table 11-42: PacketType Definition packetType Value Physical Modem Modem mode of operation PACKET_TYPE_GFSK 0x00 [default] GFSK GFSK mode PACKET_TYPE_LORA 0x01 LoRa LoRa® mode PACKET_TYPE_RANGING 0x02 LoRa Ranging Engine mode PACKET_TYPE_FLRC 0x03 FLRC FLRC mode PACKET_TYPE_BLE 0x04 GFSK BLE mode Reserved >=5 - Reserved Changing from one mode of operation to another is performed by sending the SetPacketType() command. The parameters from the previous mode are not kept internally. The transition must be performed in STDBY_RC mode. 11.7.2 GetPacketType The command GetPacketType() returns the current operating packet type of the radio. Table 11-43: GetPacketType SPI Data Transfer Byte 0 1 2 Data from host Opcode = 0x03 NOP NOP Data to host status status packetType Example1 0x03 0x00 0x00 1. Example SPI command binary pattern to get the current packet type SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 86 of 158 Semtech Table 11-44: GetPacketType UART Data Transfer Byte 0 1 2 Data from host Opcode = 0x03 0x01 - Data to host - - packetType 11.7.3 SetRfFrequency The command SetRfFrequency() is used to set the frequency of the RF frequency mode. Table 11-45: SetRfFrequency SPI Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x86 rfFrequency[23:16] rfFrequency[15:8] rfFrequency[7:0] Example1 0x86 0xB8 0x9D 0x89 1. Example SPI command binary pattern to set the RF frequency to 2.4 GHz (ie. 12098953 PLL steps, 0xB89D89) Table 11-46: SetRfFrequency UART Data Transfer Byte 0 1 2 3 4 Data from host Opcode = 0x86 0x03 rfFrequency[23:16] rfFrequency[15:8] rfFrequency[7:0] The LSB of rfFrequency is equal to the PLL step i.e. 52e6/2^18 Hz, where 52e6 is the crystal frequency in Hz. SetRfFrequency() defines the Tx frequency. The Rx frequency is down-converted to the IF. The IF is set by default to 1.3 MHz. This configuration is handled internally by the transceiver, there is no need for the user to take this offset into account when configuring SetRfFrequency. This must be called after SetPacket type. 11.7.4 SetTxParams This command sets the Tx output power using parameter power and the Tx ramp time using parameter rampTime. This command is available for all packetType. Table 11-47: SetTxParams SPI Data Transfer Byte 0 1 2 Data from host Opcode = 0x8E power rampTime Example1 0x8E 0x1F 0xE0 1. Example SPI command binary pattern to set the Transmit power to 13 dBm (ie. power 0x1F), with a ramping time of 20 us (ie. 0xE0) SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 87 of 158 Semtech Table 11-48: SetTxParams UART Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x8E 0x02 power rampTime The output power (Pout) is defined by parameter power. P out  dB  = – 18 + power PoutMin = - 18 dBm (power = 0) PoutMax = 13 dBm (power = 31) The desired power amplifier ramp time is defined using rampTime parameter according to Table 11-49. Table 11-49: RampTime Definition rampTime Value Ramp time (μs) RADIO_RAMP_02_US 0x00 2 RADIO_RAMP_04_US 0x20 4 RADIO_RAMP_06_US 0x40 6 RADIO_RAMP_08_US 0x60 8 RADIO_RAMP_10_US 0x80 10 RADIO_RAMP_12_US 0xA0 12 RADIO_RAMP_16_US 0xC0 16 RADIO_RAMP_20_US 0xE0 20 11.7.5 SetCadParams The command SetCadParams() defines the number of symbols on which Channel Activity Detected (CAD) operates. Table 11-50: CAD SPI Data Transfer Byte 0 1 Data from host Opcode = 0x88 cadSymbolNum Example1 0x88 0x80 1. Example SPI command binary pattern to use 16 symbols during CAD operations Table 11-51: CAD UART Data Transfer Byte 0 1 2 Data from host Opcode = 0x88 0x01 cadSymbolNum SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 88 of 158 Semtech The number of symbols to be used is defined in the following table. Table 11-52: CadSymbolNum Definition cadSymbolNum Value Number of symbols used for CAD LORA_CAD_01_SYMBOL 0x00 1 LORA_CAD_02_SYMBOLS 0x20 2 LORA_CAD_04_SYMBOLS 0x40 4 LORA_CAD_08_SYMBOLS 0x60 8 LORA_CAD_16_SYMBOLS 0x80 16 Notice: for symbols 1 & 2, there are higher risks of false detection. 11.7.6 SetBufferBaseAddress This command fixes the base address for the packet handing operation in Tx and Rx mode for all packet types. Table 11-53: SetBufferBaseAddress SPI Data Transfer Byte 0 1 2 Data from host Opcode = 0x8F txBaseAdress rxBaseAdress Example1 0x8F 0x80 0x00 1. Example SPI command binary pattern to set Tx buffer base address to 0x00 and Rx buffer base address to 0x80 Table 11-54: SetBufferBaseAddress UART Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x8F 0x02 txBaseAdress rxBaseAdress 11.7.7 SetModulationParams The command SetModulationParams() is used to configure the modulation parameters of the radio. The parameters passed by this function will be interpreted depending on the frame type, which should have been set to the required type before calling this function. Table 11-55: SetModulationParams SPI Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x8B param[0] param[1] param[2] Example1 0x8B 0x70 0x0A 0x01 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 89 of 158 Semtech 1. Example SPI command binary pattern to set LoRa® modulation with SF7, BW 1600, CR 4/5 if the radio was previously configured in LoRa® packet type Table 11-56: SetModulationParams UART Data Transfer Byte 0 1 2 3 4 Data from host Opcode = 0x8B 0x03 param[0] param[1] param[2] In GFSK, FLRC and BLE modems the bitrate and the bandwidth are defined by param[0] parameter as a pair of values, see Section Table 14-1: "Modulation Parameters in GFSK Mode" on page 104. The modulation index is used in conjunction with the bitrate to calculate the Frequency Deviation used for the transmission or reception. The modulation index is defined by param[1] parameter. The modulation shaping, BT, represents the Gaussian filter which can be used to filter the modulation stream at the transmitter side. BT is defined by param[2] parameter. The parameter’s meaning depends on the chosen packet type and will be defined in the chapter dedicated to the selected packet type. For the LoRa® packet type, SF corresponds to the Spreading Factor used for the LoRa® modulation. SF is defined by param[0] parameter. The BW corresponds to the bandwidth onto which the LoRa® signal is spread. BW in LoRa® is defined by param[1] parameter. The LoRa® payload features with a forward error correcting mechanism which has several levels of encoding. Coding Rate (CR) is defined by param[2] parameter in LoRa®. The definition of SetModulationParams() parameters are summarized in the following table: Table 11-57: SetModulationParams Parameters Definition Parameter BLE and GFSK FLRC LoRa® and Ranging Engine modParam1 BitrateBandwidth BitrateBandwidth SpreadingFactor modParam2 ModulationIndex CodingRate Bandwidth modParam3 ModulationShaping ModulationShaping CodingRate 11.7.8 SetPacketParams This command is used to set the parameters of the packet handling block. Table 11-58: SetPacketParams SPI Data Transfer Byte 0 1 2 3 4 5 6 7 Data from host Opcode= 0x8C SetPacketP aram1 SetPacketP aram2 SetPacketP aram3 SetPacketP aram4 SetPacketP aram5 SetPacketP aram6 SetPacketP aram7 Example1 0x8C 0x0C 0x00 0x80 0x20 0x40 0x00 0x00 1. Example SPI command binary pattern to set LoRa® parameter with 16 preamble symbols (0x0C), explicit header(0x00), 128-byte payload (0x80), CRC enable (0x20) and standard IQ (0x40) SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 90 of 158 Semtech Table 11-59: SetPacketParams UART Data Transfer Byte 0 1 2 3 4 5 6 7 8 Data from host Opcode = 0x8C 0x07 SetPacke tParam1 SetPacke tParam2 SetPacke tParam3 SetPacketP aram4 SetPacketP aram5 SetPacketP aram6 SetPacketP aram7 Interpretation by the transceiver of the packet parameters depends upon the chosen packet type. Table 11-60 outlines the parameters according to the packet type. Table 11-60: SetPacketParams Parameters Definition Parameter GFSK and FLRC BLE LoRa® and Ranging Engine SetPacketParam1 PreambleLength ConnectionState PreambleLength SetPacketParam2 SyncWordLength CrcLength HeaderType SetPacketParam3 SyncWordMatch BleTestPayload PayloadLength SetPacketParam4 HeaderType Whitening CRC SetPacketParam5 PayloadLength not used InvertIQ/chirp invert SetPacketParam6 CrcLength not used not used SetPacketParam7 Whitening not used not used The usage and definition of those parameters are described in the different packet type sections. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 91 of 158 Semtech 11.8 Communication Status Information These commands return information about the transceiver status, received packet length, reception power and several flags indicating if the packet has been correctly received. The returned parameters are common to all frames except LoRa®. 11.8.1 GetRxBufferStatus This command returns the length of the last received packet (payloadLengthRx) and the address of the first byte received (rxBufferOffset), it is applicable to all modems. The address is an offset relative to the first byte of the data buffer. Table 11-61: GetRxBufferStatus SPI Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x17 NOP NOP NOP Data to host status status rxPayloadLength rxStartBufferPointer Example1 0x17 0x00 0x00 0x00 1. Example SPI command binary pattern to get the length of last received packet and the Rx Start address pointer Table 11-62: GetRxBufferStatus UART Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x17 0x02 - - Data to host - - rxPayloadLength rxStartBufferPointer Note: In LoRa® packet type with fixed header (see Section 7.4.3 "Implicit (Fixed-length) Header Mode" on page 50) the GetRxBufferStatus always returns 0x00 for rxPayloadLength. Indeed, in this configuration, no header is present in the packet so the payload size cannot be extracted from it. However, it is possible to recover the payload size configured in the radio by direct register reading. Hence, reading register 0x901 will return the payload size. The data transfer for register reading is described in Section 11.4.2 "ReadRegister Command" on page 75. in BLE packet type, the payload length returned by GetRxBufferStatus is the payload size read in the PDU header (see Section 7.2 "BLE Packet Format" on page 46). Therefore, to read the whole content of the FIFO (PDU header and PDU payload) the user must add 2 to the payload size returned by GetRxBufferStatus. These two more bytes to read correspond to the length of the PDU header that is in the FIFO. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 92 of 158 Semtech 11.8.2 GetPacketStatus Use this command to retrieve information about the last received packet. The returned parameters are frame-dependent. The value returned by GetPacketStatus() command is packet-type-dependent, and summarized in Table 11-65. Table 11-63: GetPacketStatus SPI Data Transfer Byte 0 1 2 3 4 5 6 Data from host Opcode = 0x1D NOP NOP NOP NOP NOP NOP Data to host status status packetStatus [7:0] packetStatus [15:8] packetStatus [23:16] packetStatus [31:24] packetStatus [39:32] Example1 0x1D 0x00 0x00 0x00 0x00 0x00 0x00 1. Example SPI command binary pattern to get status flags of last received packet Table 11-64: GetPacketStatus UART Data Transfer Byte 0 1 2 3 4 5 6 Data from host Opcode = 0x1D 0x05 - - - - - Data to host - - packetStatus [0:7] packetStatus [8:15] packetStatus [16:23] packetStatus [24:31] packetStatus [32:39] In the case of LoRa® and/or Ranging Engine, there are only 2 bytes returned by the command. Table 11-65: packetStatus Definition Parameter BLE, GFSK, FLRC LoRa® and Ranging Engine packetStatus[7:0] RFU rssiSync packetStatus[15:8] rssiSync snr packetStatus[16:23] errors - packetStatus[24:31] status - packetStatus[32:39] sync - Note: snr is only available in LoRa® and Ranging Engine packet types. Table 11-66: RSSI and SNR Packet Status Value Description rssiSync RSSI value latched upon the detection of the sync address. Actual signal power is –  rssiSync   2 (dBm) snr Estimation of SNR on last packet received. In two’s compliment format multiplied by 4. Actual SNR is  snr   4 (dB) If the SNR ≤ 0, RSSI_{packet, real} = RSSI_{packet,measured} – SNR_{measured} SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 93 of 158 Semtech Table 11-67: Status Packet Status Byte PStatus3 Symbol Description bit 7:6 reserved reserved bit 5 rxNoAck bit 4:1 reserved reserved bit 0 pktSent Indicates that the packet transmission is complete. Only applicable in Tx. NO_ACK field of the received packet. Only applicable in Rx for dynamic length packets. Table 11-68: Error Packet Status Byte Error Symbol Description bit 7 reserved reserved bit 6 SyncError bit 5 LengthError sync address detection status for the current packet Only applicable in Rx when sync address detection is enabled. Asserted when the length of the received packet is greater than the Max length defined in the PAYLOAD_LENGTH parameter. Only applicable in Rx for dynamic length packets. bit 4 CrcError bit 3 AbortError bit 2 headerReceived bit 1 packetReceived bit 0 packetCtrlBusy CRC check status of the current packet. The packet is available anyway in the FIFO. Only applicable in Rx when the CRC check is enabled Abort status indicates if the current packet in Rx/Tx was aborted. Applicable both in Rx & Tx. Indicates if the header for the current packet was received. Only applicable in Rx for dynamic length packets Indicates that the packet reception is complete. Does not signify packet validity. Only applicable in Rx. Indicates that the packet controller is busy. Applicable both in Rx/Tx Table 11-69: Sync Packet Status Byte Sync Symbol Description bit 7:3 reserved reserved Code of the sync address detected 000: sync address detection error bit 2:0 syncAddrsCode 001: sync_adrs_1’ detected 010: sync_adrs_2’, detected 100: sync_adrs_3’ detected SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 94 of 158 Semtech 11.8.3 GetRssiInst This command returns the instantaneous RSSI value during reception of the packet. The command is valid for all frames. In LoRa® operation, the instantaneous RSSI is updated at every symbol received. Table 11-70: GetRssiInst SPI Data Transfer Byte 0 1 2 Data from host Opcode = 0x1F NOP NOP Data to host status status rssiInst Example1 0x1F 0x00 0x00 1. Example SPI command binary pattern to perform an instantaneous RSSI measurement Table 11-71: GetRssiInst UART Data Transfer Byte 0 1 2 Data from host Opcode = 0x1F 0x01 - Data to host - - rssiInst Table 11-72: RssiInst Definition Parameter Description rssiInst Signal power is  – rssiInst   2 (dBm) 11.9 IRQ Handling In total there are 16 possible interrupt sources depending on the chosen frame and transceiver mode. Each of them can be enabled or masked. In addition, each of them can be mapped to DIO1, DIO2 or DIO3. Table 11-73: IRQ Register Bit IRQ Description Packet 0 TxDone Tx complete GFSK/BLE/FLRC/LoRa® 1 RxDone Rx complete GFSK/BLE/FLRC/LoRa® 2 SyncWordValid Sync. word valid GFSK/BLE/FLRC 3 SyncWordError Sync. word error FLRC 4 HeaderValid Header Valid LoRa®/Ranging Engine 5 HeaderError Header Error LoRa®/Ranging Engine 6 CrcError CRC error GFSK/BLE/FLRC/LoRa® 7 RangingSlaveResponseDone Ranging response complete (Slave) Ranging Engine SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 95 of 158 Semtech Table 11-73: IRQ Register Bit IRQ Description Packet 8 RangingSlaveRequestDiscard Ranging request discarded (Slave) LoRa®/Ranging Engine 9 RangingMasterResultValid Ranging result valid (Master) Ranging Engine 10 RangingMasterTimeout Ranging timeout (Master) Ranging Engine 11 RangingSlaveRequestValid Ranging Request valid (Slave) Ranging Engine 12 CadDone Channel activity check complete LoRa®/Ranging Engine 13 CadDetected Channel activity detected LoRa®/Ranging Engine 14 RxTxTimeout Rx or Tx timeout All PreambleDetected Preamble Detected LoRa, FSK and BLE (if SetLongPreamble is activated) Advanced Ranging Done Advanced Ranging Completed Ranging Engine 15 A dedicated 16-bit register called IRQ_reg is used to log IRQ sources. Each bit corresponds to one IRQ source as described in the table above. A set of user commands is used to configure IRQ mask, DIOs mapping and IRQ clearing as explained in the next paragraphs. 11.9.1 SetDioIrqParams This command is used to enable IRQs and to route IRQs to DIO pins. Table 11-74: IRQ Mask Definition SPI Data Transfer Byte 0 1 2 3 4 5 6 7 8 Data from host OpCode = 0x8D irqMask [15:8] irqMask [7:0] dio1Mask dio1Mask dio2Mask dio2Mask dio3Mask dio3Mask [15:8] [7:0] [15:8] [7:0] [15:8] [7:0] Example1 0x8D 0x40 0x23 0x00 0x01 0x00 0x02 0x40 0x20 1. Example SPI command binary pattern to activate TxDone IRQ on DIO1, RxDone IRQ on DIO2 and HeaderError and RxTxTimeout IRQ on DIO3 Table 11-75: IRQ Mask Definition UART Data Transfer Byte 0 1 2 3 4 5 6 7 8 9 Data from host OpCode = 0x8D 0x08 irqMask [15:8] irqMask [7:0] dio1Mask dio1Mask dio2Mask dio2Mask dio3Mask dio3Mask [15:8] [7:0] [15:8] [7:0] [15:8] [7:0] An interrupt is flagged in IRQ register if the corresponding bit in flag register is set. As an example, TxDone can set bit 0 of IRQ register only if bit 0 of IrqMask is set to 1. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 96 of 158 Semtech The interrupt causes a DIO to be set if the corresponding bit in dioXMask and the irqMask are set. As an example, if bit 0 of irqMask is set to 1 and bit 0 of dio1Mask is set to 1 then a rising edge of IRQ source TxDone will be logged in IRQ register and will appear at the same time on DIO1. One IRQ can be mapped to all DIOs, one DIO can be mapped to all IRQs (an OR operation is carried out) but some IRQ source will be available only on certain modes of operation and frame type. 11.9.2 GetIrqStatus This command returns the value of the IRQ register. Table 11-76: GetIrqStatus SPI Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x15 NOP NOP NOP Data to host status status irqStatus[15:8] irqStatus[7:0] Example1 0x15 0x00 0x00 0x00 1. Example SPI command binary pattern to get the current IRQ flags Table 11-77: GetIrqStatus UART Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x15 0x02 - - Data to host - - irqStatus[15:8] irqStatus[7:0] 11.9.3 ClearIrqStatus This command clears an IRQ flag in IRQ register. Table 11-78: ClearIrqStatus SPI Data Transfer Byte 0 1 2 Data from host Opcode = 0x97 irqMask[15:8] irqMask[7:0] Example1 0x97 0xFF 0xFF 1. Example SPI command binary pattern to clear all IRQ flags Table 11-79: ClearIrqStatus UART Data Transfer Byte 0 1 2 3 Data from host Opcode = 0x97 0x02 irqMask[15:8] irqMask[7:0] SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 97 of 158 Semtech To clear an IRQ flag in IRQ register, the user should set to 1 the bit of irqMask corresponding to the IRQ flag to be cleared. As an example, if bit 0 of irqMask is set to 1 then the IRQ flag at bit 0 for IRQ register is cleared. If a DIO is mapped to a single IRQ source, the DIO is cleared if the corresponding bit in the IRQ register is cleared. If DIO is OR gated with several IRQ sources, then the DIO remains set to 1 until all bits mapped to the DIO in the IRQ register are cleared. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 98 of 158 Semtech 12. List of Commands The next table gives the list of commands and the corresponding opcode. Table 12-1: Transceiver Available Commands Command Opcode Parameters Return GetStatus 0xC0 - status WriteRegister 0x18 address[15:8], address[7:0], data[0:n] - ReadRegister 0x19 address[15:8], address[7:0] data[0:n-1] WriteBuffer 0x1A offset,data[0:n] - ReadBuffer 0x1B offset data[0:n-1] SetSleep 0x84 sleepConfig - SetStandby 0x80 standbyConfig - SetFs 0xC1 - - SetTx 0x83 periodBase, periodBaseCount[15:8], periodBaseCount[7:0] - SetRx 0x82 periodBase, periodBaseCount[15:8], periodBaseCount[7:0] - rxPeriodBase, rxPeriodBaseCount[15:8], rxPeriodBaseCount[7:0], - SetRxDutyCycle 0x94 SetCad 0xC5 - - SetTxContinuousWave 0xD1 - - SetTxContinuousPreamble 0xD2 - - SetPacketType 0x8A packetType - GetPacketType 0x03 - packetType SetRfFrequency 0x86 SetTxParams 0x8E power, rampTime - SetCadParams 0x88 cadSymbolNum - SetBufferBaseAddress 0x8F txBaseAddress, rxBaseAddress - SetModulationParams 0x8B modParam1, modParam2, modParam3 - SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP sleepPeriodBase, sleepPeriodBaseCount[15:8], sleepPeriodBaseCount[7:0] rfFrequency[23:16],rfFrequency[15:8], rfFrequency[7:0] www.semtech.com Rev 3.1 March 2020 - 99 of 158 Semtech Table 12-1: Transceiver Available Commands Command Opcode Parameters Return packetParam1, packetParam2, SetPacketParams 0x8C packetParam3, packetParam4, packetParam5, packetParam6, - packetParam7 GetRxBufferStatus 0x17 - payloadLength, rxBufferOffset GetPacketStatus 0x1D - packetStatus[39:32], packetStatus[31:24], packetStatus[23:16], packetStatus[15:8], packetStatus[7:0] GetRssiInst 0x1F - rssiInst irqMask[15:8], irqMask[7:0], SetDioIrqParams 0x8D dio1Mask[15:8],dio1Mask[7:0], dio2Mask[15:8], dio2Mask[7:0], - dio3Mask[15:8], dio3Mask[7:0] GetIrqStatus 0x15 - irqStatus[15:8], irqStatus[7:0] ClrIrqStatus 0x97 irqMask[15:8], irqMask[7:0] - SetRegulatorMode 0x96 regulatorMode - SetSaveContext 0xD5 - - SetAutoFS 0x9E 0x00: disable or 0x01: enable - SetAutoTx 0x98 time - SetLongPreamble 0x9B enable - SetUartSpeed 0x9D uartSpeed - SetRangingRole 0xA3 0x00=Slave or 0x01=Master - SetAdvancedRanging 0x9A 0x00: disable or 0x01: enable - SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.1 March 2020 100 of 158 Semtech 13. Register Map Table 13-1: List of Registers Register Name Address Bit r/w Reset Description RxGain 0x891 0:7 rw 0x25 Register determining the LNA gain regime Manual Gain Setting 0x895 0:7 rw 0x01 Manual Gain (See Section 4.2) LNA Gain Value 0x89E 0:7 rw 0x0A The LNA gain value (See Section 4.2) LNA Gain Control 0x89F 0:7 rw 0x4D Enable/Disable manual LNA gain control dB Attenuation of the peak power during synch address. By default set to 0x4 and changed to 0x7 for a bit rate and bandwidth combination of 125 kbps and BW 250 kHz: 000: 1 Synch Peak Attenuation 0x8C2 5:3 rw 0x4 001: 4 010: 8 011: 16 100: 24 101: 32 110: 48 111: 64 Payload Length 0x901 0:7 rw - The length of the received LoRa payload Indicates the LoRa modem header mode LoRa Header Mode 0x903 7 rw - 0 = Header 1 = No header Ranging Request Address Byte 3 0x912 0:7 Ranging Request Address Byte 2 0x913 0:7 Ranging Request Address Byte 1 0x914 0:7 Ranging Request Address Byte 0 0x915 0:7 0x19 Ranging Device Address Byte 3 0x916 0:7 0x00 Ranging Device Address Byte 2 0x917 0:7 Ranging Device Address Byte 1 0x918 0:7 Ranging Device Address Byte 0 0x919 0:7 Ranging Filter Window Size 0x91E 0:7 r - The number of ranging samples over which the RSSI evaluated and the results averaged. Reset Ranging Filter 0x923 6 w - Clears the samples stored in the ranging filter. Ranging Result MUX 0x924 4:5 rw 0x3 SF Additional Configuration 0x925 0:7 rw - SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP 0x00 rw rw 0x00 0x00 0x00 0x00 Ranging Address when used in Slave and Advanced Ranging mode. 0x19 www.semtech.com Rev 3.2 March 2020 Ranging Master: address of the Slave device to which request is sent. Ranging result configuration. SF range selection in LoRa mode 101 of 158 Semtech Table 13-1: List of Registers Register Name Address Bit 0x92B 0:7 Ranging Calibration Byte 1 0x92C 0:7 Ranging Calibration Byte 0 0x92D 0:7 Ranging Calibration Byte 2 r/w Reset Description 0x00 rw 0x5F The ranging calibration value 0xD2 The number of bytes of the Ranging Slave ID that are checked. 0: 8 bits Ranging ID Check Length 0x931 0:7 rw 0x03 1: 16 bits 2: 24 bits 3: 32 bits Frequency Error Correction 0x93C 0:2 0x944 0:7 0x955 0:7 FEI Byte 2 0x954 0:7 FEI Byte 1 0x955 0:7 FEI Byte 0 0x956 0:7 Ranging Result Byte 2 0x961 0:7 Ranging Result Byte 1 0x962 0:7 Ranging Result Byte 0 0x963 0:7 Ranging RSSI 0x964 0:7 rw NA Freeze Ranging Result 0x97F 1 rw - LoRa Synch Word rw rw 0x14 0x24 Crystal frequency error correction mode LoRa synch word value NA ro NA LoRa Frequency error indicator (FEI)1 NA NA ro NA The result of the last ranging exchange. NA The RSSI value of the last ranging exchange Set to preserve the ranging result for reading Preamble length in GFSK and BLE: 000: 4 bits 001: 8 (default) 010: 12 Packet Preamble Settings 0x9C1 4:6 rw 0x00 011: 16 100: 20 101: 24 110: 28 111: 32 Whitening initial value 0x9C5 0:7 CRC Polynomial Definition MSB 0x9C6 0:7 CRC Polynomial Definition LSB 0x9C7 0:7 CRC Polynomial Seed Byte 2 0x9C7 0:7 CRC Polynomial Seed Byte 1 0x9C8 0:7 CRC Polynomial Seed Byte 0 0x9C9 0:7 CRC MSB Initial Value 0x9C8 0:7 CRC LSB Initial Value 0x9C9 0:7 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP rw rw 0x01 0xFF 0xFF CRC Polynomial Definition for GFSK. 0xFF rw 0xFF CRC Seed for BLE modulation. 0xFF rw 0xFF 0xFF www.semtech.com Rev 3.2 March 2020 Data whitening seed for GFSK and BLE modulation. CRC Seed used for GFSK and FLRC modulation. 102 of 158 Semtech Table 13-1: List of Registers Register Name Address Bit r/w Reset Synch Address Control 0x9CD 0:3 rw 0x80 Sync Address 1 Byte 4 0x9CE 0:7 0x55 Sync Address 1 Byte 3 0x9CF 0:7 0x55 Sync Address 1 Byte 2 0x9D0 0:7 Sync Address 1 Byte 1 0x9D1 0:7 0x55 Sync Address 1 Byte 0 0x9D2 0:7 0x55 Sync Address 2 Byte 4 0x9D3 0:7 0x55 Sync Address 2 Byte 3 0x9D4 0:7 0x55 Sync Address 2 Byte 2 0x9D5 0:7 Sync Address 2 Byte 1 0x9D6 0:7 0x55 Sync Address 2 Byte 0 0x9D7 0:7 0x55 Sync Address 3 Byte 4 0x9D8 0:7 0x55 Sync Address 3 Byte 3 0x9D9 0:7 0x55 Sync Address 3 Byte 2 0x9DA 0:7 Sync Address 3 Byte 1 0x9DB 0:7 0x55 Sync Address 3 Byte 0 0x9DC 0:7 0x55 rw rw rw 0x55 0x55 0x55 Description The number of synch word bit errors tolerated in FLRC and GFSK modes Synch Word 1 (Also used as the BLE Access Address) SyncWord 2 SyncWord 3 1. Note: LoRa FEi is reliable only for positive SNR. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 103 of 158 Semtech 14. Transceiver Operation 14.1 GFSK Operation 14.1.1 Common Transceiver Settings After power up or hard reset the transceiver runs a brief calibration procedure then goes into STDBY_RC mode, indicated by a low state on the BUSY pin. From this state the steps (the order is important) needed to either send, or receive, a GFSK format FSK packet are indicated below: 1. If not in STDBY_RC mode, then go to this mode by sending the command: SetStandby(STDBY_RC) 2. Define the GFSK packet by sending the command: SetPacketType(PACKET_TYPE_GFSK) 3. Define the RF frequency by sending the command: SetRfFrequency(rfFrequency) The LSB of rfFrequency is equal to the PLL step i.e. 52e6/2^18 Hz. SetRfFrequency() defines the transceiver frequency. 4. Indicate the addresses where the packet handler will read (txBaseAddress in Tx) or write (rxBaseAddress in Rx) the first byte of the data payload by sending the command: SetBufferBaseAddress(txBaseAddress, rxBaseAddress) Note: txBaseAddress and rxBaseAddress are offset relative to the beginning of the data memory map. 5. Define the modulation parameters by sending command SetModulationParams(modParam1, modParam2, modParam3) The bitrate and bandwidth are configures via the modParam1 setting. Table 14-1: Modulation Parameters in GFSK Mode Parameter Symbol Value Bitrate [Mb/s] DSB Bandwidth [MHz] modParam1 GFSK_BLE_BR_2_000_BW_2_4 0x04 2 2.4 modParam1 GFSK_BLE_BR_1_600_BW_2_4 0x28 1.6 2.4 modParam1 GFSK_BLE_BR_1_000_BW_2_4 0x4C 1 2.4 modParam1 GFSK_BLE_BR_1_000_BW_1_2 0x45 1 1.2 modParam1 GFSK_BLE_BR_0_800_BW_2_4 0x70 0.8 2.4 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 104 of 158 Semtech Table 14-1: Modulation Parameters in GFSK Mode Parameter Symbol Value Bitrate [Mb/s] DSB Bandwidth [MHz] modParam1 GFSK_BLE_BR_0_800_BW_1_2 0x69 0.8 1.2 modParam1 GFSK_BLE_BR_0_500_BW_1_2 0x8D 0.5 1.2 modParam1 GFSK_BLE_BR_0_500_BW_0_6 0x86 0.5 0.6 modParam1 GFSK_BLE_BR_0_400_BW_1_2 0xB1 0.4 1.2 modParam1 GFSK_BLE_BR_0_400_BW_0_6 0xAA 0.4 0.6 modParam1 GFSK_BLE_BR_0_250_BW_0_6 0xCE 0.25 0.6 modParam1 GFSK_BLE_BR_0_250_BW_0_3 0xC7 0.25 0.3 modParam1 GFSK_BLE_BR_0_125_BW_0_3 0xEF 0.125 0.3 Table 14-2: Modulation Index Parameters in GFSK Mode Parameter Symbol Value Modindex modParam2 MOD_IND_0_35 0x00 0.35 modParam2 MOD_IND_0_5 0x01 0.5 modParam2 MOD_IND_0_75 0x02 0.75 modParam2 MOD_IND_1_00 0x03 1 modParam2 MOD_IND_1_25 0x04 1.25 modParam2 MOD_IND_1_50 0x05 1.5 modParam2 MOD_IND_1_75 0x06 1.75 modParam2 MOD_IND_2_00 0x07 2 modParam2 MOD_IND_2_25 0x08 2.25 modParam2 MOD_IND_2_50 0x09 2.5 modParam2 MOD_IND_2_75 0x0A 2.75 modParam2 MOD_IND_3_00 0x0B 3 modParam2 MOD_IND_3_25 0x0C 3.25 modParam2 MOD_IND_3_50 0x0D 3.5 modParam2 MOD_IND_3_75 0x0E 3.75 modParam2 MOD_IND_4_00 0x0F 4 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 105 of 158 Semtech Table 14-3: Modulation Shaping Parameters in GFSK Mode Parameter Symbol Value BT modParam3 BT_OFF 0x00 No filtering modParam3 BT_1_0 0x10 1 modParam3 BT_0_5 0x20 0.5 6. Define the packet settings to be used by sending the command: SetPacketParams(param[0], param[1], param[2], param[3], param[4], param[5], param[6]) • packetParam1 = PreambleLength • packetParam2 = defines the number of bytes used for Sync Word (SyncWordLength). • packetParam3 = defines the number of correlators to be used by SyncWordMatch • packetParam4 = HeaderType • packetParam5 = PayloadLength • packetParam6 = CrcLength • packetParam7 = Whitening Table 14-4: Preamble Length Definition in GFSK Packet Parameter Symbol Value Preamble length in bits packetParam1 PREAMBLE_LENGTH_04_BITS 0x00 4 packetParam1 PREAMBLE_LENGTH_08_BITS 0x10 8 packetParam1 PREAMBLE_LENGTH_12_BITS 0x20 12 packetParam1 PREAMBLE_LENGTH_16_BITS 0x30 16 packetParam1 PREAMBLE_LENGTH_20_BITS 0x40 20 packetParam1 PREAMBLE_LENGTH_24_BITS 0x50 24 packetParam1 PREAMBLE_LENGTH_28_BITS 0x60 28 packetParam1 PREAMBLE_LENGTH_32_BITS 0x70 32 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 106 of 158 Semtech The minimum preamble length when AGC is used should be 8 bits for a bit rate of 1 Mb/s. For other bit rates, the minimum number of preamble bits must be at least 16 bits. Table 14-5: Sync Word Length Definition in GFSK Packet Parameter Symbol Value Sync Word size in bytes packetParam2 SYNC_WORD_LEN_1_B 0x00 1 packetParam2 SYNC_WORD_LEN_2_B 0x02 2 packetParam2 SYNC_WORD_LEN_3_B 0x04 3 packetParam2 SYNC_WORD_LEN_4_B 0x06 4 packetParam2 SYNC_WORD_LEN_5_B 0x08 5 In transmit mode, the transceiver can use any one of three synch words. In receive mode, the receiver exploits 3 correlators to seek any one of 3 synch words simultaneously. The behaviour of the synch word in each operating mode is described in the table below: Table 14-6: Sync Word Combination in GFSK Packet Parameter Symbol Value Receive Mode Transmit Mode packetParam3 RADIO_SELECT_SYNCWORD_OFF 0x00 Disable Sync Word No Synch Word packetParam3 RADIO_SELECT_SYNCWORD_1 0x10 SyncWord1 SyncWord1 packetParam3 RADIO_SELECT_SYNCWORD_2 0x20 SyncWord2 SyncWord2 packetParam3 RADIO_SELECT_SYNCWORD_1_2 0x30 SyncWord1 or SyncWord2 SyncWord1 packetParam3 RADIO_SELECT_SYNCWORD_3 0x40 SyncWord3 SyncWord3 packetParam3 RADIO_SELECT_SYNCWORD_1_3 0x50 SyncWord1 or SyncWord3 SyncWord1 packetParam3 RADIO_SELECT_SYNCWORD_2_3 0x60 SyncWord2 or SyncWord3 SyncWord1 packetParam3 RADIO_SELECT_SYNCWORD_1_2_3 0x70 SyncWord1, SyncWord2 or SyncWord3 SyncWord1 Table 14-7: Packet Type Definition in GFSK Packet Parameter Symbol Value Packet Length mode packetParam4 RADIO_PACKET_FIXED_LENGTH 0x00 FIXED LENGTH MODE packetParam4 RADIO_PACKET_VARIABLE_LENGTH 0x20 VARIABLE LENGTH MODE SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 107 of 158 Semtech The payload length is defined by param[4] parameter. This parameter is used by the packet handler in Tx to send the exact number of bytes. In Rx variable length mode, the packet handler will filter-out all packets with size greater than Payloadlength. Table 14-8: Payload Length Definition in GFSK Packet Parameter Symbol Value description packetParam5 PAYLOAD_LENGTH [0... 255] Payload length in bytes Using the GFSK packet, the CRC can be calculated on 1 or 2 bytes or ignored. This is defined using parameter param[5]. Table 14-9: CRC Definition in GFSK Packet Parameter Symbol Value CRC type packetParam6 RADIO_CRC_OFF 0x00 No CRC packetParam6 RADIO_CRC_1_BYTES 0x10 CRC field used 1 byte packetParam6 RADIO_CRC_2_BYTES 0x20 CRC field uses 2 bytes The whitening may be enabled in parameter param[6]. Table 14-10: Whitening Enabling in GFSK Packet Parameter Symbol Value Whitening mode packetParam7 WHITENING_ENABLE 0x00 WHITENING ENABLE packetParam7 WHITENING_DISABLE 0x08 WHITENING DISABLE 7. Define Sync Word value Additionally the user should define the 40 bits of the synchronization word (SyncWord1, SyncWord2, SyncWord3). This is carried out by sending the WriteRegister() command, the next table gives the address for the Sync Word. Table 14-11: Sync Word Definition in GFSK Packet Sync Word SyncWord1 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP Bytes Address SyncWord1(39:32) 0x09CE SyncWord1(31:24) 0x09CF SyncWord1(23:16) 0x09D0 SyncWord1(15:8) 0x09D1 SyncWord1(7:0) 0x09D2 www.semtech.com Rev 3.2 March 2020 108 of 158 Semtech Table 14-11: Sync Word Definition in GFSK Packet Sync Word SyncWord2 SyncWord3 Bytes Address SyncWord2(39:32) 0x09D3 SyncWord2(31:24) 0x09D4 SyncWord2(23:16) 0x09D5 SyncWord2(15:8) 0x09D6 SyncWord2(7:0) 0x09D7 SyncWord3(39:32) 0x09D8 SyncWord3(31:24) 0x09D9 SyncWord3(23:16) 0x09DA SyncWord3(15:8) 0x09DB SyncWord3(7:0) 0x09DC A configurable number of bit-errors can be tolerated in the synch word. The desired number of bit errors permissible is written to Synch Address Control register 0x9CD. The seed used for CRC needs also to be modified for certain applications. This is carried out by direct register access using the command WriteReg(). Table 14-12: CRC Initialization Registers Parameter Bytes Address CRC init value MSB 0x9c8 CRC init value MSB 0x9c9 CrcInit The CRC polynomial can also be modified by direct register access using the command WriteReg(). Table 14-13: CRC Polynomial Definition Parameter Bytes Address Description CRC polynomial MSB 0x9C6 Defines the LSB byte of the 16-bit CRC polynomial or Defines the 8-bit CRC polynomial For example to program the following polynomial P16(x) = x^16 + x^12 + x^5 + 1 CrcPolynomial CRC polynomial LSB 0x9C7 Initialize the crc_polynomial(15:0) = 0x1021 To program the following polynomial P8(x) = x^8 + x^2 + x + 1 Initialize the crc_polynomial(7:0) = 0x07 After completing this procedure the user must proceed to either Section 14.1.2 for Tx or Section 14.1.3 for Rx. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 109 of 158 Semtech 14.1.2 Tx Setting and Operations 1. Define output power and ramp time by sending the command (see Section 11.6.4): SetTxParams(power,ramptime) 2. Send the payload to the data buffer by sending the command: WriteBuffer(offset,*data) where *data is a pointer to the payload and offset is the address at which the first byte of the payload will be located in the FIFO. The offset will correspond to txBaseAddress in normal operation. 3. Configure the DIOs and Interrupt sources (IRQs) by using command: SetDioIrqParams(IrqMask,Dio1Mask,Dio2Mask,Dio3Mask) In typical Tx operation select the following IRQ sources: • TxDone IRQ to indicate the end of packet transmission. The transceiver will be return to STDBY_RC mode at the end of the packet. • RxTxTimeout (optional) to prevent deadlock. The transceiver will return automatically to STDBY_RC mode if a timeout occurs. 4. Once configured, start transmission using command: SetTx(periodBase, periodBaseCount[15:8], periodBaseCount[7:0]) If a timeout is desired, set the periodBaseCount to a non-zero value. This timeout can be used to avoid deadlock. 5. Wait for IRQ TxDone or RxTxTimeout. Once a packet has been sent, or a timeout has occurred, the transceiver goes automatically to STDBY_RC mode. 6. Optionally, check the packet status to make sure that the packet transmission has completed, by using the command: GetPacketStatus() In this case only parameter packetStatus[3] is useful. Table 14-14: PacketStatus[3] in GFSK Packet PacketStatus[3] Symbol Description bit 7:1 Reserved Reserved bit 0 PktSent Indicates that the packet transmission is complete. Only signifies the completion of transmit process and not the packet validity. Only applicable in Tx. 7. Clear TxDone or RxTxTimeout IRQ by sending the command: ClrIrqStatus(irqMask[15:8], irqMask[7:0]) This command will reset the flag for which the corresponding bit position in irqMask is set to 1. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 110 of 158 Semtech 14.1.3 Rx Setting and Operations 1. Configure the DIOs and Interrupt sources (IRQs) by using command SetDioIrqParams(irqMask, dio1Mask, dio2Mask, dio3Mask) In typical GFSK Rx operation the user selects one or more of the following IRQ sources: • RxDone to indicate a packet has been detected. This IRQ does not mean that the packet is valid (size or CRC correct). The user must check the packet status to ensure that the valid packed is received or has enabled the other IRQ sources (such as for CRC). • SyncWordValid to indicate that a Sync Word has been detected. • CrcError to indicate that the received packet has a CRC error • RxTxTimeout to indicate that no packet has been detected in a given time frame defined by timeout parameter in the SetRx() command. Map these IRQs to one or more DIOs as desired. 2. Set the transceiver in receiver mode to start reception using command: SetRx(periodBase, periodBaseCount[15:8], periodBaseCount[7:0]) Depending on periodBaseCount, 3 possible Rx behaviours are possible: • periodBaseCount =0 : RX Single Mode. Time out is disabled; The device remains in RX mode and returns to single mode at Rx completion. • periodBaseCount is set to 0xFFFF, Rx Continuous mode, the device remains in Rx mode until the host sends a command to change the operating mode such as STDBY_RC. The device can receive several packets. Each time a packet is received, RXDone IRQ is set and the device will continue listening for a new packet. • periodBaseCount is set to another value, then Timeout is active. The device remains in Rx mode; it returns automatically to STDBY_RC Mode on timer end-of-count or when a packet has been received. As soon as a packet is detected, the timer is automatically disabled to allow complete reception of the packet. In typical cases, use a timeout and wait for IRQs RxDone or RxTxTimeout. If IRQs RxDone rises, the transceiver goes to STDBY_RC mode if single mode is used (timeout set to a value different from 0xFFFF). If Continuous mode is used (timeout set to 0xFFFF) the transceiver stays in Rx and continues to listen for a new packet. 3. Check the packet status to make sure that the packet has been received properly, by using the command: GetPacketStatus() The command returns the following parameters: • RssiSync: RSSI value at the time the Sync Word has been detected. Actual signal power is –RssiSync/2 (dBm) • packetStatus2: Gives information about the last packet received as described in the next table • packetStatus3: Unused in Rx • packetStatus4: Indicates which correlator has detected the Sync Word SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 111 of 158 Semtech Table 14-15: PacketStatus[2] in GFSK Packet PacketStatus[2] Symbol Description bit 7 Reserved Reserved Sync address detection status for the current packet bit 6 SyncError Only applicable in Rx when multiple sync address detection is enabled (will be set if multiple valid synch words are detected) bit 5 LengthError bit 4 CrcError bit 3 AbortError bit 2 HeaderReceived bit 1 PacketReceived bit 0 PacketCtrlBusy Asserted when the length of the received packet is greater than the Max length defined in the PAYLOAD_LENGTH parameter. Only applicable in Rx for dynamic length packets. CRC check status of the current packet. The packet is available anyway in the FIFO. Only applicable in Rx when the CRC check is enabled Abort status indicates if the current packet in Rx/Tx was aborted by the user. Applicable in Rx & Tx. Indicates if the header for the current packet was received. Only applicable in Rx for dynamic length packets Indicates that the packet reception is complete. Does not signify packet validity. Only applicable in Rx. Indicates that the packet controller is busy. Applicable both in Rx/Tx Table 14-16: PacketStatus[4] in GFSK Mode Packet PacketStatus[4] Symbol Description bit 7:3 Reserved Reserved Value 000: sync address detection error bit 2:0 SyncAdrsCode Code of the sync address detected 001: sync_adrs_1’ detected 010: sync_adrs_2’, detected 100: sync_adrs_3’ detected 4. Once all checks are complete, then clear the IRQs by sending the command: ClrIrqStatus(irqMask) This command will reset the flag for which the corresponding bit position in irqMask is set to 1. Note:  A DIO can be mapped to several IRQ sources (ORed with IRQ sources). The DIO will go to zero once all corresponding IRQ flags have been set to zero. 5. Get packet length and start address of the received payload issuing the command: GetRxbufferStatus() This command returns the length of the last received packet (payloadLength) and the address of the first byte received (rxBufferOffset). It is applicable to all modems. 6. Read the data buffer using the command: SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 112 of 158 Semtech ReadBuffer(offset, payloadLength) Where offset is equal to rxBufferOffset and the length of payload to receive is payloadLength. 14.2 BLE Operation 14.2.1 Common Transceiver Settings After power up or hard reset the transceiver runs a calibration procedure and goes to STDBY_RC mode indicated by a low state on BUSY pin. From this state the steps are: 1. If not in STDBY_RC mode, then go to this mode by using command: SetStandby(STDBY_RC) 2. Define BLE packet by sending command: SetPacketType(PACKET_TYPE_BLE) 3. Define the RF frequency by sending command: SetRfFrequency(rfFrequency) The LSB of rfFrequency is equal to the PLL step i.e. 52 MHz / 2^18. SetRfFrequency() defines the Tx frequency. 4. Indicate the addresses where the packet handler will read (txBaseAddress in Tx) or write (rxBaseAddress in Rx) the first byte of the data payload by sending the command: SetBufferBaseAddress(txBaseAddress, rxBaseAddress) 5. Define the modulation parameter by sending command: SetModulationParams(modParam1,modParam2,modParam3) • param[0]: bit rate and bandwidth definition. • param[1]: modulation index definition. • param[2]: pulse shaping definition In BLE case of different bit rates, modulation index and BT than the standard can be used with the packet. The following settings should be used for BLE 4.2: Table 14-17: Modulation Parameters in BLE and GFSK Mode Parameter Symbol Value BR [Mb/s] BW [MHz DSB] modParam1 BLE_BR_1_000_BW_1_2 0x45 1 1.2 For other values, see Table 14-1: "Modulation Parameters in GFSK Mode" on page 104. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 113 of 158 Semtech Table 14-18: Modulation Parameters in BLE and GFSK Mode Parameter Symbol Value Modindex modParam2 MOD_IND_0_5 0x01 0.5 For other values, see Table 14-2: "Modulation Index Parameters in GFSK Mode" on page 105. Table 14-19: Modulation Parameters in BLE and GFSK Mode Parameter Symbol Value BT modParam3 BT_0_5 0x20 0.5 For other values, see Table 14-3: "Modulation Shaping Parameters in GFSK Mode" on page 106. 6. Define the packet parameters to be used by sending the command: SetPacketParams(packetParam[0],packetParam[1],packetParam[2],packetParam[3]) • packetParam1 = ConnectionState • packetParam2 = CrcLength • packetParam3 = BleTestPayload • packetParam4 = Whitening Note: Although this command can accept up to 7 arguments, in BLE mode SetPacketParams can accept only 4. However the 3 remaining arguments must be set to 0 and sent to the radio. See Table 11-60: "SetPacketParams Parameters Definition" on page 91. Table 14-20: Connection State Definition in BLE Packet Parameter Symbol Value Maximum Payload Size [bytes] Bluetooth® Version packetParam1 BLE_PAYLOAD_LENGTH_MAX_31_BYTES 0x00 31 Bluetooth® 4.1 and above packetParam1 BLE_PAYLOAD_LENGTH_MAX_37_BYTES 0x20 37 Bluetooth® 4.1 and above packetParam1 BLE_TX_TEST_MODE 0x40 63 Bluetooth® 4.1 and above packetParam1 BLE_PAYLOAD_LENGTH_MAX_255_BYTES 0x80 255 Bluetooth® 4.2 and above Table 14-21: CRC Definition in BLE Packet Parameter Symbol Value Packet Length Mode Bluetooth® Compatibility packetParam2 BLE_CRC_OFF 0x00 No CRC No packetParam2 BLE_CRC_3B 0x10 CRC field used 3bytes Yes SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 114 of 158 Semtech Table 14-22: Tx Test Packet Payload in Test Mode for BLE Packet Value should be written to packetParam3 to produce the corresponding output sequence: Parameter Symbol Value Payload Content Pseudo Random Binary Sequence based on 9th degree polynomial packetParam3 BLE_PRBS_9 P7(x) = x9+ x5+ 1 0x00 PRBS9 sequence ‘1111111110000011110 1....’ (in transmission order shown) packetParam3 BLE_EYELONG_1_0 0x04 Repeated ‘11110000’ (in transmission order shown) sequence packetParam3 BLE_ EYESHORT_1_0 0x08 Repeated ‘10101010’ (in transmission order shown) sequence packetParam3 BLE_PRBS_15 0x0C packetParam3 BLE_ ALL_1 0x10 Repeated ‘11111111’ (in transmission order shown) sequence packetParam3 BLE_ ALL_0 0x14 Repeated ‘11111111’ (in transmission order shown) sequence packetParam3 BLE_ EYELONG_0_1 0x18 Repeated ‘00001111’ (in transmission order shown) sequence packetParam3 BLE_ EYESHORT_0_1 0x1C Repeated ‘01010101’ (in transmission order shown) sequence Pseudo Random Binary Sequence based on 15th degree polynomial P15(x) = x15+ x14+ x13 + x12+ x2+ x + 1 Note: PacketParam3 is ignored in case PacketParam1 is not BLE_TX_TEST_MODE. Table 14-23: Whitening Enabling in BLE Packet Parameter Symbol Value Whitening Mode packetParam4 BLE_WHITENING_ENABLE 0x00 WHITENING ENABLE packetParam4 BLE_WHITENING_DISABLE 0x08 WHITENING DISABLE 1 1. Whitening disable is for PacketParam1 as BLE_TX_TEST_MODE. Note: for the value, refer to the BLE specification. 7. Define the Access Address value SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 115 of 158 Semtech In addition to these parameters, the user needs to define the 32-bit synchronization word SyncWord1. This is carried out by sending the WriteRegister() command, the next table gives the address for the Sync Word. Table 14-24: Access Address Definition in BLE Packet Access Address Bytes Address Access Adddress 1(31:24) 0x09CF Access Adddress 1(23:16) 0x09D0 Access Adddress 1(15:8) 0x09D1 Access Adddress 1(7:0) 0x09D2 Access Adddress 1 The seed used for CRC needs also to be modified for certain applications. This is carried out by direct register access by sending the function WriteRegister(). Table 14-25: CRC Initialization Registers Parameter Bytes Address 0x9C7 (MSB) CrcInit CRC init value 0x9C8 0x9C9 (LSB) 14.2.2 Tx Setting and Operations 1. Define the BLE Access Address accessAddress by issuing WriteRegister() commands on the following registers: Table 14-26: BLE Access Address Configuration for Tx Register Address Value 0x09CF accessAddress (31:24) 0x09D0 accessAddress (23:16) 0x09D1 accessAddress (15:8) 0x09D2 accessAddress (7:0) 2. Define the output power and ramp time by sending the command: SetTxParam(power,ramptime) 3. Contrarily to other modems, the payload to be written in BLE mode in the data buffer of the SX1280 chip must contain a BLE header. The BLE header to add at the beginning of the payload must correspond to the BLE mode selected at step 6 in Section 14.2.1 "Common Transceiver Settings" on page 113 . See Figure 7-5: PDU Header Format for the header definition. Send the payload to the data buffer by issuing the command: SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 116 of 158 Semtech WriteBuffer(offset,data) where data is the payload containing the BLE header to be sent and offset is the address at which the first byte of the payload will be located in the FIFO. 4. Configure the DIOs and Interrupt sources (IRQs) by using command: SetDioIrqParams(irqMask, dio1Mask, dio2Mask, dio3Mask) In typical Tx operation one can select one or several IRQ sources: • TxDone IRQ to indicate the end of packet transmission. The transceiver will be in STDBY_RC mode. • RxTxTimeout (optional) to make sure no deadlock can happen. The transceiver will return automatically to STDBY_RC mode if a timeout occurs. 5. Once configured, set the transceiver in transmitter mode to start transmission using command: SetTx(periodBase, periodBaseCount[15:8], periodBaseCount[7:0]) If a timeout is desired, set periodBaseCount to a value different from zero. This timeout can be used to avoid deadlock. Wait for IRQ TxDone or RxTxTimeout Once a packet has been sent or a timeout occurred, the transceiver goes automatically to STDBY_RC mode 6. Optionally check the packet status to make sure that the packet has been sent properly by issuing the command: GetPacketStatus() In this case only parameter packetStatus3 is useful. Table 14-27: PacketStatus3 in BLE Packet PacketStatus3 Symbol Description bit 7:1 reserved Reserved bit 0 PktSent Indicates that the packet transmission is complete. Does not signify packet validity. Only applicable in Tx. 7. Clear TxDone or RxTxTimeout IRQ by sending the command: ClrIrqStatus(irqMask) This command will reset the flag for which the corresponding bit position in irqMask is set to 1. 14.2.3 Rx Setting and Operations 1. Configure the DIOs and Interrupt sources (IRQs) by using command: SetDioIrqParams(irqMask, dio1Mask, dio2Mask, dio3Mask) In typical BLE Rx operation one can select one or more of the following IRQ sources • RxDone to indicate a packet has been detected. This IRQ does not mean that the packet is valid (size or CRC correct). The user must check the packet status to ensure that the valid packed is received. • SyncWordValid to indicate that a Sync Word has been detected. • CrcError to indicate that the received packet has a CRC error • RxTxTimeout to indicate that no packet has been detected in a given time packet defined by the timeout parameter in the SetRx() command. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 117 of 158 Semtech Map these IRQs to one DIO (DIO1 or DIO2 or DIO3). 2. Once configured, set the transceiver in receiver mode to start reception using command: SetRx(periodBase, periodBaseCount[15:8], periodBaseCount[7:0]) Depending on periodBaseCount, 3 possible Rx behaviors are possible: • periodBaseCount is set to 0, then no Timeout, Rx Single mode, the device will stay in Rx mode until a reception occurs and the devices return in STDBY_RC mode upon completion. • periodBaseCount is set to 0xFFFF, Rx Continuous mode, the device remains in Rx mode until the host sends a command to change the operation mode. The device can receive several packets. Each time a packet is received, a packet received indication is given to the host and the device will continue to search for a new packet. • periodBaseCount is set to another value, then Timeout is active. The transceiver remains in Rx mode; it returns automatically to STDBY_RC Mode on timer end-of-count or when a packet has been received. As soon as a packet is detected, the timer is automatically disabled to allow complete reception of the packet. 3. In typical cases, use a timeout and wait for IRQ RxDone or RxTxTimeout. If IRQ RxDone is asserted, the transceiver goes to STDBY_RC mode if single mode is used (timeout set to a value different from 0xFFFF). If Continuous mode is used (timeout set to 0xFFFF) the transceiver stays in Rx and continues to listen for a new packet. 4. Check the packet status to make sure that the packet has been correctly received by using the command: GetPacketStatus() The command returns the following parameters: • RssiSync: RSSI value at the time the Sync Word has been detected • packetStatus2: Gives information about the last packet received as described in the next table Table 14-28: PacketStatus2 in BLE Mode • PacketStatus2 Symbol Description bit 7 Reserved Reserved bit 6 SyncError bit 5 lengthError bit 4 CrcError bit 3 AbortError bit 2 HeaderReceived bit 1 PacketReceived bit 0 PacketCtrlBusy Sync address detection status for the current packet Only applicable in Rx when sync address detection is enabled. Asserted when the length of the received packet is greater than the Max length defined in the PAYLOAD_LENGTH parameter. Only applicable in Rx for dynamic length packets. CRC check status of the current packet. The packet is available anyway in the FIFO. Only applicable in Rx when the CRC is enabled Abort status indicates if the current packet in Rx/Tx was aborted. Applicable both in Rx & Tx. Indicates if the header for the current packet was received. Only applicable in Rx for dynamic length packets Indicates that the packet reception is complete. Does not signify packet validity. Only applicable in Rx. Indicates that the packet controller is busy. Applicable both in Rx/Tx packetStatus3: In BLE packet, this status indicates in Tx mode if a packet has been sent or not SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 118 of 158 Semtech • packetStatus4: Indicates which correlator has detected the Sync Word. In case of BLE, only sync_adrs_1 is used. Table 14-29: PacketStatus4 in BLE Mode PacketStatus4 Symbol Description bit 7:3 Reserved Reserved Code of the sync address detected bit 2:0 0x0: sync address detection error SyncAdrsCode 0x1: sync_adrs_1’ detected others: reserved 5. Once all checks are complete, clear IRQs by sending the command: ClrIrqStatus(irqMask) This command will reset the flag for which the corresponding bit position in irqMask is set to 1. Note: A DIO can be mapped to several IRQ sources (ORed with IRQ sources). The DIO will be set to zero once IRQ flag has been set to zero. 6. Get packet length and start address of the received payload issuing the command: GetRxbufferStatus() This command returns the length of the last received packet (payloadLength) and the address of the first byte received (rxBufferOffset) It is applicable to all modems. The address is an offset relative to the first byte of the data buffer. 7. Read the data buffer using the command: ReadBuffer(offset, payloadLength) Where offset is equal to rxBufferOffset. 14.2.4 BLE Specific Functions 14.2.4.1 SetAutoTx() One additional command is available to ease the implementation of the BLE packet. BLE requires that the transceiver is able to send back a response 150 μs after a packet reception. This is carried out by sending the command SetAutoTx() that allows the transceiver to send a packet a user programmable time (time) after the end of a packet reception. SetAutoTx(time) must be issued in STDBY_RC mode. Table 14-30: SetAutoTx Mode Byte 0 1 2 Data from host Opcode = 0x98 time(15:8) time(7:0) SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 119 of 158 Semtech time is in μs. The delay between the end of reception of a packet and the start of the transmission of the next packet is defined by: Tx Delay = time – offset Where offset is a time needed for the transceiver to switch modes and is equal to 33 μs. Once this command is issued, each time the transceiver receives a packet, it will automatically switch to Tx and transmit a packet after a predefined time. If the user wants to have normal operation (going in STDBY_RC after Tx), the user needs to send the command SetAutoTx() with the time parameter set to zero. If the user wants to discard only the next automatic packet transmission, the user needs to send the command SetStandby() after the reception of a packet. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 120 of 158 Semtech 14.3 FLRC Operation 14.3.1 Common Transceiver Settings After power up or hard reset the transceiver runs a calibration procedure and goes to STDBY_RC mode indicated by a low state on BUSY pin. From this state the steps are: 1. If not in STDBY_RC mode, then go to this mode by sending the command: SetStandby(STDBY_RC) 2. Define the FLRC packet type by sending the command: SetPacketType(PACKET_TYPE_FLRC) 3. Define the RF frequency by sending the command: SetRfFrequency(rfFrequency) The LSB of rfFrequency is equal to the PLL step i.e. 52e6/2^18 Hz. SetRfFrequency() defines the Tx frequency. 4. Indicate the addresses where the packet handler will read (txBaseAddress in Tx) or write (rxBaseAddress in Rx) the first byte of the data payload by sending the command: SetBufferBaseAddress(txBaseAddress, rxBaseAddress) Note: txBaseAddress and rxBaseAddress are offsets from the beginning of the data memory map. 5. Define the modulation parameter by sending command: SetModulationParams(modParam1, modParam2, modParam3) The bit rate and bandwidth are linked via param[0]. The coding rate used in error correction mechanism is defined in param[1] and the BT is defined in param[2]. Table 14-31: Modulation Parameters in FLRC Mode: Bandwidth and Bit Rate Parameter Symbol Value Bit Rate [Mb/s] Bandwidth [MHz DSB] modParam1 FLRC_BR_1_300_BW_1_2 0x45 1.3 1.2 modParam1 FLRC_BR_1_000_BW_1_2 0x69 1.04 1.2 modParam1 FLRC_BR_0_650_BW_0_6 0x86 0.65 0.6 modParam1 FLRC_BR_0_520_BW_0_6 0xAA 052 0.6 modParam1 FLRC_BR_0_325_BW_0_3 0xC7 0.325 0.3 modParam1 FLRC_BR_0_260_BW_0_3 0xEB 0.26 0.3 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 121 of 158 Semtech Table 14-32: Modulation Parameters in FLRC Mode: Coding Rate Parameter Symbol Value Coding rate modParam2 FLRC_CR_1_2 0x00 ½ modParam2 FLRC_CR_3_4 0x02 ¾ modParam2 FLRC_CR_1_1 0x04 1 modParam2 Reserved Greater or equal to 3 Reserved Table 14-33: Modulation Parameters in FLRC Mode: BT Parameter Symbol Value BT modParam3 BT_DIS 0x00 No filtering modParam3 BT_1 0x10 1 modParam3 BT_0_5 0x20 0.5 6. Define the packet format to be used by sending the command: SetPacketParams(packetParam1, packetParam2, packetParam3, packetParam4, packetParam5, packetParam6, packetParam7) • packetParam1 = AGCPreambleLength • packetParam2 = SyncWordLength • packetParam3 = SyncWordMatch • packetParam4 = PacketType • packetParam5 = PayloadLength • packetParam6 = CrcLength • packetParam7 = Whitening Table 14-34: AGC Preamble Length Definition in FLRC Packet Parameter Symbol Value Preamble length in bits packetParam1 PREAMBLE_LENGTH_4_BITS 0x00 Reserved packetParam1 PREAMBLE_LENGTH_8_BITS 0x10 8 packetParam1 PREAMBLE_LENGTH_12_BITS 0x20 12 packetParam1 PREAMBLE_LENGTH_16_BITS 0x30 16 packetParam1 PREAMBLE_LENGTH_20_BITS 0x40 20 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 122 of 158 Semtech Table 14-34: AGC Preamble Length Definition in FLRC Packet Parameter Symbol Value Preamble length in bits packetParam1 PREAMBLE_LENGTH_24_BITS 0x50 24 packetParam1 PREAMBLE_LENGTH_28_BITS 0x60 28 packetParam1 PREAMBLE_LENGTH_32_BITS 0x70 32 The minimum preamble length when AGC is used (see Section 4.2 for manual gain selection) is 8 bits for a bit rate of 1 Mb/s. For other bit rates, the minimum number of preamble bits is 16 bits. The number of bytes used for Sync Word is defined by packetParam2. The user can rely on the built-in 21-bit preamble always required to detect start of packet or add 4 additional Sync Word for address detection in case of multiple devices. Table 14-35: Sync Word Length Definition in FLRC Packet Parameter Symbol Value Sync Word size in bytes packetParam2 FLRC_SYNC_NOSYNC 0x00 21 bits preamble packetParam2 FLRC_SYNC_WORD_LEN_P32S 0x04 21 bits preamble + 32 bits Sync Word A configurable number of bit-errors can be tolerated in the synch word. The desired number of bit errors permissible is written to Synch Address Control register 0x9CD: this is a direct binary mapping with 0 meaning no error is tolerated and 15 meaning up to 15 bit errors will be tolerated. With 3 correlators, the transceiver can search for upto 3 Sync Words at the time. The combination of Sync Word detection is defined by parameters PacketParam3. Table 14-36: Sync Word Combination in FLRC Packet Parameter Symbol Value Sync Word combination to use packetParam3 RX_DISABLE_SYNC_WORD 0x00 Disable Sync Word packetParam3 RX_MATCH_SYNC_WORD_1 0x10 SyncWord1 packetParam3 RX_MATCH_SYNC_WORD_2 0x20 SyncWord2 packetParam3 RX_MATCH_SYNC_WORD_1_2 0x30 packetParam3 RX_MATCH_SYNC_WORD_3 0x40 packetParam3 RX_MATCH_SYNC_WORD_1_3 0x50 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 SyncWord1 or SyncWord2 SyncWord3 SyncWord1 or SyncWord3 123 of 158 Semtech Table 14-36: Sync Word Combination in FLRC Packet Parameter Symbol Value packetParam3 RX_MATCH_SYNC_WORD_2_3 0x60 packetParam3 RX_MATCH_SYNC_WORD_1_2_3 0x70 Sync Word combination to use SyncWord2 or SyncWord3 SyncWord1 or SyncWord2 or SyncWord3 The payload length is defined by packetParam4. In fixed length mode, this parameter is used by the packet handler in Tx to send the exact number of payload bytes. In Rx, in variable length mode, the packet handler will filter-out all packets with size greater than Payload length. Note: Minimum payload length is 6 bytes. Table 14-37: Packet Type Definition in FLRC Packet Parameter Symbol Value Packet Length mode packetParam4 PACKET_FIXED_LENGTH 0x00 FIXED LENGTH MODE packetParam4 PACKET_VARIABLE_LENGTH 0x20 VARIABLE LENGTH MODE Table 14-38: Payload Length Definition in FLRC Packet Parameter Symbol Value Description packetParam5 PAYLOAD_LENGTH [6 ... 127] Payload length in bytes In FLRC mode, the CRC can be calculated on 2, 3 or 4 bytes or ignored. This is defined using parameter param[5]. Table 14-39: CRC Definition in FLRC Packet Parameter Symbol Value CRC type packetParam6 CRC_OFF 0x00 No CRC packetParam6 CRC_2_BYTE 0x10 CRC field uses 2 bytes packetParam6 CRC_3_BYTE 0x20 CRC field uses 3bytes packetParam6 CRC_4_BYTE 0x30 CRC field uses 4bytes SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 124 of 158 Semtech The seed used for CRC needs also to be modified for certain applications. This is carried out by direct register access by sending the function WriteRegister(). Table 14-40: CRC Initialization Registers Parameter Bytes Address CRC init value MSB 0x9C8 CRC init value LSB 0x9C9 CrcInit The CRC polynomial of the FLRC modem is fixed and, depending upon the CRC length is given below: CRC 16 bits: 0x755B P16(x) = x16 + x14 + x13 + x12 + x10 + x8 + x6 + x4 + x3 + x + 1 CRC 24 bits: 0x5D6DCB P24(x) = x24 + x22 + x20 + x19 + x18 + x16 + x14 + x13 + x11 + x10 + x8 + x7+ x6 + x3 + x + 1 CRC 32 bits: 0xF4ACFB13 P32(x) = x32 + x31 + x30 + x29 + x28 + x26 + x23 + x21 + x19 + x18 + x15 + x14 + x13 + x12 + x11 + x9 + x8 + x4 + x3 + x + 1 It is not possible to enable whitening when using the FLRC packet type. The value of packetParam7 must always be set to disabled. Table 14-41: Whitening Definition in FLRC Packet Parameter Symbol Value Description packetParam7 WHITENING 0x08 Whitening disabled 7. Define Sync Word value In addition to these parameters, the user needs to define the synchronization word (SyncWord1, SyncWord2, SyncWord3). This is carried out by sending the WriteRegister() command. The table below gives the address for the Sync Word. Table 14-42: Sync Word Definition in FLRC Packet Sync Word Bytes Address SyncWord1[31:24] 0x09CF SyncWord1[23:16] 0x09D0 SyncWord1[15:8] 0x09D1 SyncWord1[7:0] 0x09D2 SyncWord1 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 125 of 158 Semtech Table 14-42: Sync Word Definition in FLRC Packet Sync Word Bytes Address SyncWord2[31:24] 0x09D4 SyncWord2[23:16] 0x09D5 SyncWord2[15:8] 0x09D6 SyncWord2[7:0] 0x09D7 SyncWord3[31:24] 0x09D9 SyncWord3[23:16] 0x09DA SyncWord3[15:8] 0x09DB SyncWord3[7:0] 0x09DC SyncWord2 SyncWord3 14.3.2 Tx Setting and Operations 1. Define output power and ramp time by sending the command: SetTxParam(power,rampTime) 2. Write the payload to the data buffer with the command: WriteBuffer(offset,data) where data is the payload to be sent and offset is the address at which the first byte of the payload will be located in the buffer. Offset will correspond to txBaseAddress in normal operation. 3. Configure the DIOs and Interrupt sources (IRQs) by sending the command: SetDioIrqParams(irqMask,dio1Mask,dio2Mask,dio3Mask) In a typical Tx operation the following IRQ.s are selected: • TxDone IRQ to indicate the end of packet transmission. The transceiver will be in STDBY_RC mode. • RxTxTimeout (optional) to make sure no deadlock can happen. The transceiver will return automatically to STDBY_RC mode if a timeout occurs. 4. Once configured, set the transceiver in transmitter mode to start transmission using command: SetTx(periodBase, periodBaseCount[15:8], periodBaseCount[7:0]) If a timeout is desired, set periodBaseCount value different to zero. This timeout can be used to avoid deadlock. Wait for IRQ TxDone or RxTxTimeout. Once a packet has been sent or a timeout occurs, the transceiver automatically transitions to STDBY_RC mode. 5. Optionally check the packet status to make sure that the packet has been sent correctly without user intervention by using the command: GetPacketStatus() In this case only the parameter packetStatus3 is useful. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 126 of 158 Semtech Table 14-43: PacketStatus3 in FLRC Packet PacketStatus3 Symbol Description bit 7:1 reserved reserved bit 0 PktSent Indicates that the packet transmission is complete. Only signifies the completion of transmit process and not the packet validity. Only applicable in Tx. 6. Clear TxDone or RxTxTimeout IRQ by sending the command: ClrIrqStatus(irqMask) This command will reset the flag for which the corresponding bit position in irqMask is set to 1. 14.3.3 Rx Setting and Operations 1. Configure the DIOs and Interrupt sources (IRQs) by sending the command: SetDioIrqParams(IrqMask,Dio1Mask,Dio2Mask,Dio3Mask) In a typical FLRC Rx operation one or several IRQ sources may be selected: • RxDone to indicate a packet has been detected. This IRQ does not mean that the packet is valid (size or CRC correct). The user must check the packet status to ensure that the valid packed is received. • SyncWordValid to indicate that a Sync Word has been detected. • CrcError to indicate that the received packet has a CRC error • RxTxTimeout to indicate that no packet has been detected in a given time frame defined by timeout parameter in the SetRx() command. Map these IRQs to one DIO (DIO1 or DIO2 or DIO3). 2. Once configured, set the transceiver in receiver mode to start reception using command: SetRx(periodBase, periodBaseCount[15:8], periodBaseCount[7:0]) Depending on periodBaseCount, 3 possible Rx behaviour are possible: • periodBaseCount is set to 0, then no timeout, Rx Single mode, the device will stay in Rx mode until a reception occurs and the devices return in STDBY_RC mode upon completion. • periodBaseCount is set 0xFFFF, Rx Continuous mode, the device remains in Rx mode until the host sends a command to change the operation mode. The device can receive several packets. Each time a packet is received, a packet reception indication is given to the host and the device will continue to search for a new packet. • periodBaseCount is set to another value, then Timeout is active. The device remains in Rx mode; it returns automatically to STDBY_RC Mode on timer end-of-count or when a packet has been received. As soon as a packet is detected, the timer is automatically disabled to allow complete reception of the packet. 3. Typically, use a timeout and wait for IRQ RxDone or RxTxTimeout. If IRQ RxDone rises, the transceiver goes to STDBY_RC mode if single mode is used (timeout set to a value different from 0xFFF). If Continuous mode is used (timeout set to 0xFFFF) the transceiver stays in Rx and continues to listen for a new packet. 4. Check the packet status to make sure that the packet has been received properly, by sending the command: SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 127 of 158 Semtech GetPacketStatus() The command returns the following parameters: • RssiSync: RSSI value at the time the Sync Word was detected. Actual signal power is –RssiSync/2 (dBm) • packetStatus2: Gives information about the last packet received as described in the next table • packetStatus3: In FLRC packet, this status indicates in Tx mode if a packet has been sent or not • packetStatus4: Indicates which correlator has detected the Sync Word Table 14-44: PacketStatus2 in FLRC Packet PacketStatus2 Symbol Description bit 7 Reserved Reserved bit 6 SyncError bit 5 LengthError Sync address detection status for the current packet Only applicable in Rx when sync address detection is enabled. Asserted when the length of the received packet is greater than the Max length defined in the PAYLOAD_LENGTH parameter. Only applicable in Rx for dynamic length packets. bit 4 CrcError bit 3 AbortError bit 2 HeaderReceived bit 1 PacketReceived bit 0 PacketCtrlBusy CRC check status of the current packet. The packet is available anyway in the FIFO. Only applicable in Rx when the CRC is enabled Abort status indicates if the current packet in Rx/Tx was aborted. Applicable both in Rx & Tx. Indicates if the header for the current packet was received. Only applicable in Rx for dynamic length packets Indicates that the packet reception is complete. Does not signify packet validity. Only applicable in Rx. Indicates that the packet controller is busy. Applicable both in Rx/Tx Table 14-45: PacketStatus3 in FLRC Packet PacketStatus3 Symbol Description bit 7:1 Reserved Reserved bit 0 PktSent SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP Indicates that the packet transmission is complete. Does not signify packet validity. Only applicable in Tx. www.semtech.com Rev 3.2 March 2020 128 of 158 Semtech Table 14-46: PacketStatus4 in FLRC Packet PacketStatus4 Symbol Description bit 7:3 Reserved Reserved Code of the sync address detected 000: sync address detection error bit 2:0 SyncSdrsCode 001: sync_adrs_1’ detected 010: sync_adrs_2’, detected 100: sync_adrs_3’ detected 5. Once all checks are complete, clear the IRQs by sending the command: ClrIrqStatus(irqMask) This command will reset the flag for which the corresponding bit position in irqMask is set to 1. Note:  A DIO can be mapped to several IRQ sources (ORed with IRQ sources). The DIO will go to zero once IRQ flag has been set to zero. 6. Get the packet length and the start address of the received payload by sending the command: GetRxBufferStatus() This command returns the length of the last received packet (payloadLength) and the address of the first byte received (rxBufferOffset) It is applicable to all modems. The address is an offset relative to the first byte of the data buffer. 7. Read the data buffer using the command: ReadBuffer(offset, payloadLength) Where offset is equal to rxBufferOffset and the command contains payloadLength. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 129 of 158 Semtech 14.4 LoRa® Operation 14.4.1 Common Transceiver Settings for LoRa® After power up or hard reset the transceiver runs a calibration procedure and goes to STDBY_RC mode indicated by a low state on BUSY pin. From this state the steps are 1. If not in STDBY_RC mode, then go to this mode by sending the command: SetStandby(STDBY_RC) 2. Define the LoRa® packet type by sending the command: SetPacketType(PACKET_TYPE_LORA) 3. Define the RF frequency by sending the command: SetRfFrequency(rfFrequency) The LSB of rfFrequency is equal to the PLL step i.e. 52e6/2^18 Hz. SetRfFrequency() defines the Tx frequency. 4. Indicate the addresses where the packet handler will read (txBaseAddress in Tx) or write (rxBaseAddress in Rx) the first byte of the data payload by sending the command: SetBufferBaseAddress(txBaseAddress, rxBaseAddress) Note: txBaseAddress and rxBaseAddress are offset relative to the beginning of the data memory map. 5. Define the modulation parameter by sending the command: SetModulationParams(modParam1,modParam2, modParam3) modParam1 defines the signal BW, modeParam2 defines SF and modParam3 defines the coding rate (CR). Table 14-47: Modulation Parameters in LoRa® Mode Parameter Symbol Value Spreading factor modParam1 LORA_SF_5 0x50 5 modParam1 LORA_SF_6 0x60 6 modParam1 LORA_SF_7 0x70 7 modParam1 LORA_SF_8 0x80 8 modParam1 LORA_SF_9 0x90 9 modParam1 LORA_SF_10 0xA0 10 modParam1 LORA_SF_11 0xB0 11 modParam1 LORA_SF_12 0xC0 12 SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 130 of 158 Semtech After SetModulationParams command: • If the Spreading Factor selected is SF5 or SF6, it is required to use WriteRegister( 0x925, 0x1E ) • If the Spreading Factor is SF7 or SF-8 then the command WriteRegister( 0x925, 0x37 ) must be used • If the Spreading Factor is SF9, SF10, SF11 or SF12, then the command WriteRegister( 0x925, 0x32 ) must be used • In all cases 0x1 must be written to the Frequency Error Compensation mode register 0x093C Table 14-48: Modulation Parameters in LoRa® Mode Parameter Symbol Value Bandwidth [kHz] modParam2 LORA_BW_1600 0x0A 1625.0 modParam2 LORA_BW_800 0x18 812.5 modParam2 LORA_BW_400 0x26 406.25 modParam2 LORA_BW_200 0x34 203.125 Table 14-49: Modulation Parameters in LoRa® Mode Parameter Symbol Value Coding rate modParam3 LORA_CR_4_5 0x01 4/5 modParam3 LORA_CR_4_6 0x02 4/6 modParam3 LORA_CR_4_7 0x03 4/7 modParam3 LORA_CR_4_8 0x04 4/8 modParam3 LORA_CR_LI_4_5 0x05 4/5* modParam3 LORA_CR_LI_4_6 0x06 4/6* modParam3 LORA_CR_LI_4_8 0x07 4/8* * A new interleaving scheme has been implemented to increase robustness to burst interference and/or strong Doppler events. The FEC has been kept the same to limit the impact on complexity. Long interleaving is selected by setting modParam3 = 0x5, 0x6 or 0x7(LORA_CR_LI_4_5,LORA_CR_LI_4_6 or LORA_CR_LI_4_8). Coding rate is signaled in header. Previously, only values 0x0 to 0x4 were valid. The coding rate values respectively 4/5, 4/6, 4/8. So LORA_CR_LI_4_5 is like LORA_CR_4_5 , LORA_CR_LI_4_6 like LORA_CR_4_6, LORA_CR_LI_4_8 like LORA_CR_4_8 with a different interleaving scheme. Long interleaving is compatible with implicit header. Scrambling occurs with long interleaving, as with legacy interleaving. Note: There is a limitation on maximum payload length for LORA_CR_LI_4_8. Payload length should not exceed 253 bytes if CRC is enabled. 6. Define the packet format to be used by sending the command: SetPacketParams(pktParam1, pktParam2, pktParam3, pktParam4, pktParam5) • packetParam1 = PreambleLength, which defines the preamble length (in symbols) to be used mainly by the packet handling in Tx mode. • packetParam2 = HeaderType SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 131 of 158 Semtech • packetParam3 = PayloadLength • packetParam4 = CRC • packetParam5 = InvertIQ/chirp invert • packetParam1 defines the preamble length number expressed in LoRa® symbols. Recommended value is 12 symbols. Table 14-50: Preamble Definition in LoRa® or Ranging Parameter Symbol Value Preamble length in symbols packetParam1(3:0) LORA_PBLE_LEN_MANT [1:15] packetParam1(7:4) LORA_PBLE_LEN_EXP [1:15] preamble length = LORA_PBLE_LEN_MANT*2^(LORA_PBLE_LEN_EXP) The type of packet is defined by parameter PacketParam2. For fixed-length packet, no header is included and implicit header mode is selected. In variable length packet, the explicit header mode is used. Table 14-51: Packet Type Definition in LoRa® or Ranging Packet Parameter Symbol Value Header mode packetParam2 EXPLICIT_HEADER 0x00 EXPLICIT HEADER packetParam2 IMPLICIT_HEADER 0x80 IMPLICIT HEADER The payload length is defined in packetParam3. Table 14-52: Payload Length Definition in LoRa® Packet Parameter Symbol Value PayloadLength packetParam3 PayloadLength [1….255] PayloadLength Note: There is a limitation on maximum payload length for LORA_CR_LI_4_8. Payload length should not exceed 253 bytes if CRC is enabled. The CRC usage is defined in packetParam4. Table 14-53: CRC Enabling in LoRa® Packet Parameter Symbol Value CRC mode packetParam4 LORA_CRC_ENABLE 0x20 CRC ENABLE packetParam4 LORA_CRC_DISABLE 0x00 CRC DISABLE SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 132 of 158 Semtech The IQ swapping is defined by PacketParam5. Note, that an IQ inverted packet will be undetectable by a non-inverted Rx. Table 14-54: IQ Swapping in LoRa® or Ranging Packet Parameter Symbol Value LoRa® IQ swap packetParam5 LORA_IQ_INVERTED 0x00 IQ swapped packetParam5 LORA_IQ_STD 0x40 IQ standard It is also possible to configure the LoRa SyncWord. With the 1 byte SynchWord taking the format 0xXY, it is written across the MSB of two registers as described below: -write X in the register@0x944, in position [7:4] without modifying [3:0] (using a Read / Modify / Write operation) -write Y in the register@0x945, in position [7:4] without modifying [3:0] (using a Read / Modify / Write operation) 14.4.2 Tx Setting and Operations 1. Define the output power and ramp time by sending the command: SetTxParam(power,rampTime) 2. Send the payload to the data buffer by sending the command: WriteBuffer(offset,*data) where *data is a pointer to the payload and offset is the address at which the first byte of the payload will be located in the buffer. Offset will correspond to txBaseAddress in normal operation. 3. Configure the DIOs and Interrupt sources (IRQs) by sending the command: SetDioIrqParams(irqMask,dio1Mask,dio2Mask,dio3Mask) In a typical Tx operation the user can select one or several IRQ sources: • TxDone IRQ to indicate the end of packet transmission. The transceiver will be in STDBY_RC mode. • RxTxTimeout (optional) to make sure no deadlock can happen. The transceiver will return automatically to STDBY_RC mode if a timeout occurs. 4. Once configured, set the transceiver in transmitter mode to start transmission by sending the command: SetTx(periodBase, periodBaseCount[15:8], periodBaseCount[7:0]) If a timeout is desired, set periodBaseCount to a non-zero value. This timeout can be used to avoid deadlock. Wait for IRQ TxDone or RxTxTimeout Once a packet has been sent or a timeout has occurred, the transceiver goes automatically to STDBY_RC mode. 5. Clear TxDone or RxTxTimeout IRQ by sending the command: ClrIrqStatus(irqStatus) This command will reset the flag for which the corresponding bit position in irqStatus is set to 1. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 133 of 158 Semtech 14.4.3 Rx Setting and Operations 1. Configure the DIOs and Interrupt sources (IRQs) by using command: SetDioIrqParams(irqMask,dio1Mask,dio2Mask,dio3Mask) In a typical LoRa® Rx operation the user could select one or several of the following IRQ sources: • RxDone to indicate a packet has been detected. This IRQ does not mean that the packet is valid (size or CRC correct). The user must check the packet status to ensure that a valid packed has been received. • PreambleValid is available to indicate a vaid loRa preamble has been detected. • HeaderValid (and HeaderError) are available to indicate whether a valid packet header has been received. • SyncWordValid to indicate that a Sync Word has been detected. • CrcError to indicate that the received packet has a CRC error • RxTxTimeout to indicate that no packet has been detected in a given time frame defined by timeout parameter in the SetRx() command. 2. Once configured, set the transceiver in receiver mode to start reception using command: SetRx(periodBase, periodBaseCount[15:8], periodBaseCount[7:0]) Depending on periodBaseCount, 3 possible Rx behaviors are possible: • periodBaseCount is set 0, then no Timeout, Rx Single mode, the device will stay in Rx mode until a reception occurs and the device returns to STDBY_RC mode upon completion. • periodBaseCount is set 0xFFFF, Rx Continuous mode, the device remains in Rx mode until the host sends a command to change the operation mode. The device can receive several packets. Each time a packet is received, a packet received indication is given to the host and the device will continue to search for a new packet. • periodBaseCount is set to another value, then Timeout is active. The device remains in Rx mode; it returns automatically to STDBY_RC Mode on timer end-of-count or when a packet has been received. As soon as a packet is detected, the timer is automatically disabled to allow complete reception of the packet. 3. In typical cases, use a timeout and wait for IRQ RxDone or RxTxTimeout. If IRQ RxDone is asserted, the transceiver goes to STDBY_RC mode if single mode is used (timeout set to a value different from 0xFFFF). If Continuous mode is used (timeout set to 0xFFFF) the transceiver stays in Rx and continues to listen for a new packet. 4. Check the packet status to make sure that the packet has been received properly, by sending the command: GetPacketStatus() The command returns the following parameters: • SnrPkt Estimation of SNR on last packet received. In two’s compliment format multiplied by 4. Actual SNR in dB =SnrPkt/4 , noting that only negative values should be used. 5. Once all checks are complete, clear IRQs by sending the command: ClrIrqStatus(irqMask) This command will reset the flag for which the corresponding bit position in irqMask is set to 1. Note: A DIO can be mapped to several IRQ sources (ORed with IRQ sources). The DIO will go to zero once IRQ flag has been set to zero. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 134 of 158 Semtech 6. Get the packet length and start address of the received payload by sending the command: GetRxBufferStatus() This command returns the length of the last received packet (payloadLengthRx) and the address of the first byte received (rxStartBufferPointer). It is applicable to all modems. The address is an offset relative to the first byte of the data buffer. 7. Read the data buffer using the command: ReadBuffer(offset, payloadLengthRx) Where offset is equal to rxStartBufferPointer and payloadLengthRx is the size of buffer to read. 8. Optionally, the frequency error indicator (FEI) can be read from register 0x0954 (MSB) 0x0955, 0x0956 (LSB). The FEI is 2's complement (signed) 20 bit number: SignedFEIReading. This must be converted from two’s compliment to a signed FEI reading then, in turn, can be converted to a frequency error in Hz using the following formula: SignedFeiReading FrequencyError  Hz  = 1.55x ---------------------------------------------------1600 ------------------------BW  kHz  The resolution of the frequency error indicator measurement in LoRa mode is given by: FEI_RES [Hz] = 1 / (64 * Ts) Where Ts is the LoRa symbol time. The table below shows all possible FEI resolution combinations versus SF and bandwidth. (All values in milliseconds). Table 14-55: LoRa FEI Measurement Resolution [Hz ] SF/BW 1625 kHz 812 kHz 406 kHz 203 kHz 5 793 396 198 99 6 397 198 99 50 7 99 50 25 12 8 50 25 12 6 9 50 25 12 6 10 25 12 6 3 11 12 6 3 2 12 6 3 2 1 Note also that the sign of the FEI reading will change if the IQ of the receiver is inverted. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 135 of 158 Semtech 14.5 Ranging Operation Ranging is a round-trip time of flight measurement between a pair of SX1280 transceivers configured as a ranging Master radio and a ranging Slave. The following section will introduce the configuration required for ranging operation. These configuration steps must be reproduced identically on both Master and Slave, except where explicitly stated otherwise. 14.5.1 Ranging Device Setting The ranging settings for both master and slave are given below: 1. If not in STDBY_RC mode, go to this mode by sending the command: SetStandby(STDBY_RC) 2. Set the packet type to ranging by sending the command: SetPacketType(PACKET_TYPE_RANGING) 3. Set the modulation parameters for the ranging operation by sending the command: SetModulationParams(modParamSF,modParamBW, modParamCR) The definition of the three arguments of the SetModulationParams is the same as for LoRa® settings. However, for ranging operation, the use of SF11 and SF12 is not permitted. Similarly, the bandwidth configuration for ranging operations is restricted to the values 406.25 kHz, 812.5 kHz and 1625 kHz. The following table summarizes the acceptable values for SetModulationParams command (the three arguments can be combined in any way): Table 14-56: Ranging Device Modulation Parameters modParamSF modParamBW modParamCR LORA_SF_5 LORA_BW_400 LORA_CR_4_5 LORA_SF_6 LORA_BW_800 LORA_CR_4_6 LORA_SF_7 LORA_BW_1600 LORA_CR_4_7 LORA_SF_8 - LORA_CR_4_8 LORA_SF_9 - - LORA_SF_10 - - 4. Set the packet parameters by the command: SetPacketParams( preambleLength, headerType, payloadLength, crcMode, invertIq ) The signification of the arguments is similar to the one of LoRa® SetPacketParams usage. 5. Set the RF frequency to use by the command: SetRfFrequency( rfFrequency ) The rfFrequency is to be provided as a number of PLL step (ie. 52e6/(2^18) Hz). SetRfFrequency() defines the Tx frequency. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 136 of 158 Semtech 6. Set the Tx parameters by: SetTxParams( txPower, rampTime) 7. During ranging operation, multiple slaves and multiple masters can be within range of communication. However, the ranging operation must use only one slave and one master. To help slaves distinguish the master to respond to and other masters within range, and to address a specific slave, the ranging requests contain an address field which is checked by slave on ranging request reception. On slave only, use the WriteRegister command to set the address the slave can respond to. The registers to write are given by the following table (for addresses less than 32 bits the LSBs are considered): Table 14-57: Slave Ranging Request Address Definition Slave Ranging req address Address RangingRangingAddress[31:24] 0x916 RangingRangingAddress[23:16] 0x917 RangingRangingAddress[15:8] 0x918 RangingRangingAddress[7:0] 0x919 The slave also requires the number of address bits to be checked by issuing a WriteRegister command with the following parameters: Table 14-58: Register Address Bit Definition Register Address Field 0x931 Value Number of Address Bits Checked 0x0 8 bits 0x1 16 bits 0x2 24 bits 0x3 32 bits 7:6 The Master also needs to use the same address, as this is the address to which the ranging request will be issued. It is set by issuing the WriteRegister command to the following registers: Table 14-59: Master Ranging Request Address Definition Master Ranging Request Address Address RangingRequestAddress[31:24] 0x912 RangingRequestAddress[23:16] 0x913 RangingRequestAddress[15:8] 0x914 RangingRequestAddress[7:0] 0x915 8. Set the IRQ that should be generated by the radio for ranging operations using the command: SetDioIrqParams( irqMask, dio1Mask, dio2Mask, dio3Mask ) SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 137 of 158 Semtech The IRQs to be activated depend of the ranging role of the sx1280. For the Master typical ranging operations require the following IRQs: • RangingMasterResultValid • RangingMasterResultTimeout For the Slave the typical IRQs are: • RangingSlaveResponseDone • RangingSlaveRequestDiscarded 9. The ranging process needs a calibration value to compensate the Rx-Tx delay offset. The calibration value is set by calling WriteRegister command on the following registers: Table 14-60: Calibration Value in Register Calibration Value Register Calibration[15:8] 0x92C Calibration[7:0] 0x92D The calibration value is a function of SF, BW and of any group delay seen by the propagating RF ranging signal. A rudimentary calibration can be applied using the values above. For more details about calibration in ranging, see the Application Note “Introduction to Ranging for SX1280” on www.semtech.com. 10. The role of the SX1280 in ranging operation must be explicitly given issuing the following command: SetRangingRole( role ) Where role value is provided by the following table: Table 14-61: Ranging Role Value Ranging Role Value Master 0x01 Slave 0x00 11. Finally, use the following commands to start the ranging procedure: • On Slave side: SetRx( periodBaseRx, periodCountRx ) • On Master side: SetTx( periodBaseTx, periodCountTx ) If there is no timing constraint in the application level, it is advised to use the continuous mode (ie. PeriodCount=0xFFFF). The ranging modem automatically manages the transition from Rx to Tx for Slave, and from Tx to Rx for Master. SX1280/SX1281 Data Sheet DS.SX1280-1.W.APP www.semtech.com Rev 3.2 March 2020 138 of 158 Semtech 12. The ranging results are accessible only from the Master. When Master generates the IRQ RangingMasterResultValid, the ranging result is ready to be read from the three registers detailed below: Table 14-62: Register Result Address Register Address Ranging Result 0x961 RangingResult[23:16] 0x962 RangingResult[15:8] 0x963 RangingResult[7:0] The ranging results can, optionally, be post processed using the internal filtering of the SX1280. The ranging result can be recovered at various points throughout the filtering process. The process is as follows: 1. The raw ranging results are collected. 2. A sliding window of samples is recovered, the length of the window is determined by the value of register address 0x91E the size of the averaging window RangingFilterWindowSize is limited from 8 to 255. 3. The maximum received RSSI received in the RangingFilterWindowSize results is determined. 4. The RangingFilterRssiThresholdOffset set by the contents of register value 0x953 determines the relative power below (in dB) which samples from our sample window will be rejected (default value is 0x24). 5. The remaining results are averaged and returned as the ranging result. At any time the filter window samples can be reset by setting bit 6 of register 0x923. The ranging result value optionally be preserved by setting bit 1 of register 0x97f, Freeze Ranging Result. The output format of the ranging result will depend upon the setting of RangingResMux: Table 14-63: Ranging Result Type Selection RangingResMux(5:4) Ranging Output Type Output Conversion to Distance [m] 00 Raw result Step 1 Distance [m] = RangingResult*150/(2^12*BW) 01 Average RSSI filtered result Step 5 with BW in MHz Due to the particular usage of the ranging result register, the following procedure is required to read the ranging result: 1. Set the radio in Oscillator mode with SetStandby( STDBY_XOSC ) 2. Enable clock in LoRa® memory: WriteRegister( 0x97F, ReadRegister( 0x97F ) | ( 1