Method receive

libraries/RS485/RS485.cpp:170–266

returns true if complete message is captured. multiple calls needed as it should be non-blocking.

//  returns true if complete message is captured.
//  multiple calls needed as it should be non-blocking.
bool RS485::receive(uint8_t &senderID, uint8_t msg[], uint8_t &msglen)
{
  static uint8_t state  = 0;
  static uint8_t sender = 255;  //  unknown / anonymous.
  static uint8_t length = 0;
  static bool    forMe  = false;
  uint8_t        CHKSUM = 0;

  if (_stream->available() == 0) return false;

  uint8_t v = _stream->read();
  //  if (debug) Serial.print(v, HEX);

  switch(state)
  {
    //  waiting for new packet
    case 0:
      if (v == SOH)
      {
        _bidx = 0;        // start new packet
        state = 1;
      }
      break;

    //  extract receiver
    case 1:
      forMe = ((v == _deviceID) || (v == 255));  //  PM or broadcast?
      if (not forMe) state = 99;
      else state = 2;
      break;

    //  extract sender
    case 2:
      sender = v;
      state = 3;
      break;

    //  extract length
    case 3:
      msglen = v;
      state = 3;
      break;

    //  expect STX
    case 4:
      if (v == STX) state = 5;
      else state = 99;
      break;

    //  extract message
    case 5:
      if (length == 0)
      {
        state = 6;
        break;
      }
      // error handling  if v not ascii ?
      _buffer[_bidx++] = v;