查看SX126x的源代码

== 各模式中断产生 ==

=== set_rx(timeout)===

timeout 为 24bit （最长可设置时间 (2^24-1) * 15.625us = 262s），timeout = 0xFF FFFF 时，为持续接收模式 (Continous RX)。

'''timeout 时长不够，可能会读取同一个数据包好几次。。。'''
* SF10 + CR4/6：数据位扩为 x1.5 (每 4bit 增加 2bit），10 个 4bit 组编码为 6 个 symbol
* 42 Bytes , 1~3/4~7/8~11... 共 11 个 6 symbol，66 x 2.048ms = 135.168ms


set_dio_irq_params() 只开启：

<source lang=bash>
SX126X_IRQ_RX_DONE | SX126X_IRQ_TIMEOUT | SX126X_IRQ_CRC_ERR
</source>

set_rx() 进入接收模式后，可能产生的中断：

* 主要产生 RX_DONE
* RX_DONE 和 CRC_ERR 会同时置位
* Continous RX 亦有可能产生 TIMEOUT 中断，即便所有 Timer 都没有设置

<source lang=bash>
[ 7539.366831] sx126x spi1.0: irq state 0x42         # IRQ_CRC_ERR & IRQ_RX_DONE
[ 7539.370941] sx126x sx126x0: crc err
</source>

<br>

=== RX Duty ===

  /*
   * rxTime: 1ms
   * sleepTime: 200ms
  */
  SetRxDutyCycle( rxTime, sleepTime );

用于减少接收功耗。rxTime 和 sleepTime 都是 24bit，最长可设置时间 (2^24-1) * 15.625us = 262s

Required to have a preamble emission time long enough to cover:
  sleepPeriod + preamble/header detection
  即：sleepPeriod + 8 symbols（显头固定长度）

发射方的 preamble_len 需要足够长（最大 65535）：
* '''setup_v0()''' 模式下，单 symbol 约 2ms，前导 8+4.25 个 symbol，则前导码约 24.5ms，因此如测试 RX duty 模式宜 rx_win: 1ms，sleep_win: 8ms
* 设置前导长 108 symbol，则 108+4.25，剔除显头固定的 8 symbol，sleepPeriod 可设为 200ms，48Bytes 的包，总发射时为 406ms


StopTimerOnPreamble() 用于规范接收到  false header 后行为：
* StopTimerOnPreamble(true)，则检测到 false header 后，继续在 rx 模式（5mA 左右），直到收到下一个 true header
* StopTimerOnPreamble(false)，则检测到 false header 后，Timer 活着，一个时间窗口后，即产生 rxTimeout irq，并退回 sleep 模式


参考：AN1200.36_SX1261-2_RxDutyCycle_V1.0.pdf

<br>

=== Continous RX ===

该模式下，仍然产生各种中断：
* IRQ_PREAMBLE_DETECTED
* IRQ_HEADER_VALID (+30ms)
* IRQ_TIMEOUT & IRQ_CAD_DETECTED
* IRQ_HEADER_ERR
* IRQ_RX_DONE (+100ms) & IRQ_CRC_ERR


建议用 set_dio_irq_params() 开启所有 IRQ （只开启 RX_DONE | CRC_ERR | TIMEOUT 会造成读取错误数据包）：

<source lang=cpp>
sx126x_set_dio_irq_params(dev, SX126X_IRQ_ALL, SX126X_IRQ_ALL, SX126X_IRQ_NONE, SX126X_IRQ_NONE);
</source>

10:30 - 15:00 接收数据，SPI 16M：
<source lang=cpp>
  1000s:
  * cnt_crc_err: 68
  * cnt_rx:      346
  * cnt_rx255:   406
  4000s:
  * cnt_crc_err: 255
  * cnt_rx:      1460
  * cnt_rx255:   1717
enable tx_boost, 8000s:
  * cnt_crc_err: 360
  * cnt_rx:      2627
  * cnt_rx255:   3235
</source>
cnt_rx / cnt_rx255 始终 0.85 左右


11/20 9:40 开始，SPI 16M
<source lang=bash>
3000s:
  * cnt_crc_err: 202
  * cnt_rx:      988
  * cnt_rx255:   1257
4000s:
  * cnt_crc_err: 260
  * cnt_rx:      1323
  * cnt_rx255:   1725
enable tx_boost, 8000s:
  * cnt_crc_err: 360
  * cnt_rx:      2627
  * cnt_rx255:   3235
enable tx_boost, 15200s:
  * cnt_crc_err: 777
  * cnt_rx:      5208
  * cnt_rx255:   6236
</source>

11/27 16:30 左右 SPI 8M
<source lang=bash>
cch 2000S:
  * cnt_crc_err: 266
  * cnt_rx:      2984
  * cnt_rx255:   0
dch 300s:
  * cnt_crc_err:22
  * cnt_rx:      396
  * cnt_rx255:   0

radio0 (SPI 4M) & radio1 (SPI 8M) 同时，1500s:
  * cnt_crc_err: 212
  * cnt_rx:      2282
  * cnt_rx255:   0

  * cnt_crc_err: 137
  * cnt_rx:      2017
  * cnt_rx255:   0
</source>

11/28 11:20 开始：
<source lang=cpp>
 SPI0 2M + SPI1 8M 1400s
  * cnt_crc_err: 148
  * cnt_rx:      1332
  * cnt_rx255:   0

  * cnt_crc_err: 180
  * cnt_rx:      2383
  * cnt_rx255:   0

SPI0 12M + SPI1 8M 3300s
  * cnt_crc_err: 457
  * cnt_rx:      4836
  * cnt_rx255:   388

  * cnt_crc_err: 82
  * cnt_rx:      1247
  * cnt_rx255:   0
</source>

cch (radio0) 需要：  
  echo 8 >/sys/class/sx126x/radio0/pre_len && echo 472500000 >/sys/class/sx126x/radio0/freq
  echo RX_CON >/sys/class/sx126x/radio0/rx_mode && echo RX_CON >/sys/class/sx126x/radio1/rx_mode

才能正常接收


一个有效接收可能产生的中断：

<source lang=bash>
[  111.479486] sx126x spi1.0: irq state 0x04         # IRQ_PREAMBLE_DETECTED
[  112.446459] sx126x spi1.0: irq state 0x04         # IRQ_PREAMBLE_DETECTED
[  112.483135] sx126x spi1.0: irq state 0x10         # IRQ_HEADER_VALID
[  112.487350] sx126x sx126x0: Header Valid for received payload
[  112.606014] sx126x spi1.0: irq state 0x02         # IRQ_RX_DONE
[  112.610270] sx126x spi1.0: FIFO read: 36 from 0xe4
[  112.616506] rx: 47 4f 34 00 00 00 02 e3 9a 12 e2 01 4a 0e 56 02  GO4.........J.V.
[  112.624091] rx: 08 00 04 0b 16 04 0b 18 00 00 00 04 00 02 04 48  ...............H
[  112.631754] rx: 9a 6c 8f 22
[  112.913692] sx126x spi1.0: irq state 0x300        # IRQ_TIMEOUT & IRQ_CAD_DETECTED
[  112.917988] sx126x sx126x0: Tx or Rx timeout
[  116.042765] sx126x spi1.0: irq state 0x04         # IRQ_PREAMBLE_DETECTED
[  116.078858] sx126x spi1.0: irq state 0x300       # IRQ_TIMEOUT & IRQ_CAD_DETECTED
[  116.083053] sx126x sx126x0: Tx or Rx timeout
[  116.201725] sx126x spi1.0: irq state 0x02         # IRQ_RX_DONE
[  116.206084] sx126x spi1.0: FIFO read: 36 from 0x08
[  116.211163] rx: 47 4f 33 00 00 00 02 e4 d8 3c 93 0b b8 0e 07 02  GO3......<......
[  116.218796] rx: 00 00 00 00 fe 16 02 58 00 00 00 04 00 00 05 a2  .......X........
[  116.226382] rx: 4e 33 5e 0f  
</source>


Continous RX 模式下，Enable IRQ_ALL，对类似 IRQ_HEADER_VALID、IRQ_PREAMBLE_DETECTED、 IRQ_TIMEOUT、IRQ_CAD_DETECTED 中断进行 clear_irq() 可以提高从 buffer 解包数据的正确性：

<source lang=bash>
[ 9951.480925] sx126x spi1.0: irq state 0x02
[ 9951.485287] sx126x spi1.0: Rx FIFO: 36 Bytes @ 0xea
[ 9951.490470] rx: 47 4f 33 00 00 00 02 cc 0b 57 b2 ff ec 0e 17 02  GO3......W......
[ 9951.498110] rx: 00 00 00 00 fe 12 fe fe 00 00 00 00 32 fc 08 f7  ............2...
[ 9951.505700] rx: fc 4e 62 b7                                      .Nb.
[ 9951.796843] sx126x spi1.0: irq state 0x04
[ 9951.831965] sx126x spi1.0: irq state 0x10
[ 9951.954882] sx126x spi1.0: irq state 0x300
[ 9952.303437] sx126x spi1.0: irq state 0x04
[ 9952.339928] sx126x spi1.0: irq state 0x300
[ 9952.462799] sx126x spi1.0: irq state 0x300
[ 9953.438117] sx126x spi1.0: irq state 0x300
[ 9953.473598] sx126x spi1.0: irq state 0x10
[ 9953.596473] sx126x spi1.0: irq state 0x300
[ 9954.575904] sx126x spi1.0: irq state 0x300
[ 9954.611397] sx126x spi1.0: irq state 0x300
[ 9954.734278] sx126x spi1.0: irq state 0x300
[ 9955.044056] sx126x spi1.0: irq state 0x04
[ 9955.078832] sx126x spi1.0: irq state 0x10
[ 9955.201722] sx126x spi1.0: irq state 0x02
[ 9955.206095] sx126x spi1.0: Rx FIFO: 36 Bytes @ 0x9e
[ 9955.211273] rx: 47 4f 33 00 00 00 02 ea ce 42 54 0b b8 0e 53 02  GO3......BT...S.
[ 9955.218914] rx: 00 01 0a 16 fe 14 01 2a b7 b2 00 14 00 09 07 23  .......*.......#
[ 9955.226504] rx: a8 87 98 d0                                      ....
[ 9955.347561] sx126x spi1.0: irq state 0x300
[ 9955.512402] sx126x spi1.0: irq state 0x300
[ 9955.549066] sx126x spi1.0: irq state 0x300
[ 9955.671928] sx126x spi1.0: irq state 0x300
[ 9955.973515] sx126x spi1.0: irq state 0x04
[ 9956.008291] sx126x spi1.0: irq state 0x10
[ 9956.131136] sx126x spi1.0: irq state 0x300
[ 9956.676438] sx126x spi1.0: irq state 0x300
[ 9956.711175] sx126x spi1.0: irq state 0x10
[ 9956.834011] sx126x spi1.0: irq state 0x300
[ 9957.164285] sx126x spi1.0: irq state 0x300
[ 9957.200151] sx126x spi1.0: irq state 0x300
[ 9957.322975] sx126x spi1.0: irq state 0x300
[ 9957.483283] sx126x spi1.0: irq state 0x300
[ 9957.520345] sx126x spi1.0: irq state 0x300
[ 9957.643218] sx126x spi1.0: irq state 0x02
[ 9957.647595] sx126x spi1.0: Rx FIFO: 255 Bytes @ 0x24
[ 9957.652626] sx126x sx126x0: payload len is 0
[ 9957.700262] sx126x spi1.0: irq state 0x300
[ 9958.350278] sx126x spi1.0: irq state 0x300
[ 9959.484997] sx126x spi1.0: irq state 0x300
[ 9959.521237] sx126x spi1.0: irq state 0x300
[ 9959.644097] sx126x spi1.0: irq state 0x02
[ 9959.648453] sx126x spi1.0: Rx FIFO: 36 Bytes @ 0x76
[ 9959.653635] rx: 47 4f 33 00 00 00 02 ea ce 40 ec 0b b8 0e 3f 02  GO3......@....?.
[ 9959.661275] rx: 00 01 0a 25 fe 16 01 2a 2b 4e 00 14 00 1c 06 d9  ...%...*+N......
[ 9959.668867] rx: a9 37 12 8d   
</source>

<br>