Method mcp2518fd_ReceiveMessageGet

src/mcp2518fd_can.cpp:1412–1513

}

int8_t mcp2518fd::mcp2518fd_ReceiveMessageGet(CAN_FIFO_CHANNEL channel,
                                              CAN_RX_MSGOBJ *rxObj,
                                              uint8_t *rxd, uint8_t nBytes) {
  uint8_t n = 0;
  uint8_t i = 0;
  uint16_t a;
  uint32_t fifoReg[3];
  REG_CiFIFOCON ciFifoCon;
  REG_CiFIFOUA ciFifoUa;
  int8_t spiTransferError = 0;

  // Get FIFO registers
  a = cREGADDR_CiFIFOCON + (channel * CiFIFO_OFFSET);

  spiTransferError = mcp2518fd_ReadWordArray(a, fifoReg, 3);
  if (spiTransferError) {
    return -1;
  }

  // Check that it is a receive buffer
  ciFifoCon.word = fifoReg[0];
  ciFifoCon.txBF.TxEnable = 0;
  if (ciFifoCon.txBF.TxEnable) {
    return -2;
  }

  // Get address
  ciFifoUa.word = fifoReg[2];
#ifdef USERADDRESS_TIMES_FOUR
  a = 4 * ciFifoUa.bF.UserAddress;
#else
  a = ciFifoUa.bF.UserAddress;
#endif
  a += cRAMADDR_START;

  // Number of bytes to read
  n = nBytes + 8; // Add 8 header bytes

  if (ciFifoCon.rxBF.RxTimeStampEnable) {
    n += 4; // Add 4 time stamp bytes
  }

  // Make sure we read a multiple of 4 bytes from RAM
  if (n % 4) {
    n = n + 4 - (n % 4);
  }

  // Read rxObj using one access
  uint8_t ba[MAX_MSG_SIZE];

  if (n > MAX_MSG_SIZE) {
    n = MAX_MSG_SIZE;
  }

  spiTransferError = mcp2518fd_ReadByteArray(a, ba, n);
  if (spiTransferError) {
    return -3;
  }