SX126x

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目录

1 Overview

  • SX1262: (+22dBm), 150-960 MHz (e.g. 430/490MHz, 868/915MHz), Rx Current 4.6mA, QFN 4x4mm
  • SX1261: (+15dBm), 150-960 MHz (e.g. 430/490MHz, 868/915MHz), Rx Current 4.6mA, QFN 4x4mm
  • SX1268: (+22dBm), 410-810 MHz, Rx Current 4.6mA, QFN 4x4mm


  • 4.2 mA of active receive current consumption
  • 25 mA TX @ 14dbm
  • Programmable bit rate up to 62.5 kbps LoRa and 300 kbps FSK
  • High sensitivity: down to -148 dBm


https://www.semtech.com/products/wireless-rf/lora-transceivers/sx1262


2 Notes

2.1 Busy Ctrl Line

Used to indicate the status of the internal state machine.

The amount of time the BUSY line is stay HIGH.

When the BUSY line is held low, it indicates that the internal state machine is in idle mode and that the radio is ready to accept a command from the host controller.

The BUSY line is set back to zero once the chip has reached a stable mode and it's ready for a new command


2.2 RF Switch

  • DIO2 控制 RF Switch 之 ctrl,用于切换 RF1 (RF_OUT) 还是 RF2 (RF_IN) 连接到 RFC (ANT)


对于 RF switch PE4259:

  • Pin 6 (~CTRL) = VDD (3.3V Max), Pin 4 (CTRL) = High ------> RF1 (RFO, Pin1) -> RFC
  • Pin 6 (~CTRL) = VDD (3.3V Max), Pin 4 (CTRL) = Low ------> RF2 (RFI, Pin3) -> RFC

PE4259.pinmap.png


2.3 SetModulationParams

  • cmd opcode: 0x8B
  • cmd format: 0x8B param1 param2 ... param4
  • param1: SF
    • 0xA (SF10)
    • 0xC (SF12)
  • param2: BW
    • 0x04 (BW125KHz)
    • 0x05 (BW250KHz)
    • 0x06 (BW500KHz)
  • param3: CR
    • 0x01 (CR 4/5)
    • 0x02 (CR 4/6)
  • param4: LowDataRateOptimize
    • 0x00: Off
    • 0x01: On

  • LowDataRateOptimize -----> 1: Enabled; mandated for when the symbol length exceeds 16ms
  • AgcAutoOn -----> 1: LNA gain set by the internal AGC loop


2.4 SetPacketParams

  • cmd opcode: 0x8C
  • cmd format: 0x8C param1 param2 ... param6
  • param1 & param2: PreambleLength, 0x1 ~ 0xFFFF
  • param3: HeaderType
    • 0x0: variable length packet (explicite header)
    • 0x1: fixed length packet (implicite header)
  • param4: PayloadLength: 0x0 - 0xFF
  • param5: CRC Type
    • 0x0: CRC off
    • 0x1: CRC on
  • param6: InvertQ
    • 0x0: standard IQ setup
    • 0x1: Inverted IQ setup


2.5 SetTx

  • cmd opcode: 0x83
  • cmd format: 0x83 param1 param2 param3
    • param1 ... param3: timeout[23:0] 高字节在前
    • timeout = 0: Timeout disable, Tx single mode, the device will stay in TX mode utile the the packet is transmitted and returns in STBY_RC mode upon completion
    • timeout = others: Timeout active, the device remains in Tx mode it returns automatically to STBY_RC mode on timer end-of-count or when a packet has been transmitted. The maximum timeout is then 262s.


2.6 SetBufferBaseAddress

  • cmd opcode: 0x8F
  • cmd format: 0x8F param1 param2
  • param1: TX base addr
  • param2: RX base addr



3 Pinmap

Sx126x.pinmap.png


4 Application Schematics

4.1 Power

Sx126x-power.png


4.2 TCXO

Sx126x-TXCO-ctrl-block.png


4.3 参考实现

  • DC-DC 使用常用的 Option C
  • XTAL 使用的是非温补晶振,现在基本都使用 TCXO 了,这个要注意一下,实现的时候替换为 TCXO

Sx126x.app.sch.png


5 Module Pinmap

Sx126x-pinmap.jpg


6 Reference



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