src/python/bootloader.py

   1
   2 INIT_SEQ = {
   3     "CRSF": [0xEC,0x04,0x32,ord('b'),ord('l')],
   4     "GHST": [0x89,0x04,0x32,ord('b'),ord('l')],
   5 }
   6
   7 BIND_SEQ = {
   8     "CRSF": [0xEC,0x04,0x32,ord('b'),ord('d')],
   9     "GHST": [0x89,0x04,0x32,ord('b'),ord('d')],
  10 }
  11
  12 MODEL_SEQ = [0xEC,0x04,0x32,ord('m'),ord('m')]
  13
  14 def calc_crc8(payload, poly=0xD5):
  15     crc = 0
  16     for data in payload:
  17         crc ^= data
  18         for _ in range(8):
  19             if crc & 0x80:
  20                 crc = (crc << 1) ^ poly
  21             else:
  22                 crc = crc << 1
  23     return crc & 0xFF
  24
  25 def get_telemetry_seq(seq, key=None):
  26     payload = list(seq)
  27     if payload:
  28         if key:
  29             if type(key) == str:
  30                 key = [ord(x) for x in key]
  31             payload += key
  32             payload[1] += len(key)
  33         payload += [calc_crc8(payload[2:])]
  34     return bytes(payload)
  35
  36 def get_init_seq(module, key=None):
  37     return get_telemetry_seq(INIT_SEQ.get(module, []), key)
  38
  39 def get_bind_seq(module, key=None):
  40     return get_telemetry_seq(BIND_SEQ.get(module, []), key)
  41
  42 def get_model_seq(model):
  43     return get_telemetry_seq(MODEL_SEQ, model)
  44
  45 if __name__ == '__main__':
  46     print("CRC: %s" % get_init_seq('CRSF', [ord(x) for x in 'R9MM']))
  47     print("CRC: %s" % get_init_seq('CRSF', 'R9MM'))