MCP2515 basic reading (and writing)

gistfile1.ino

byte i=0;

// CAN message frame (actually just the parts that are exposed by the MCP2515 RX/TX buffers)
Frame message;

void loop() {
  
  message.id = 0;
  
  // This implementation utilizes the MCP2515 INT pin to flag received messages or other events
  if(CAN.Interrupt()) {
    // determine which interrupt flags have been set
    byte interruptFlags = CAN.Read(CANINTF);
    
    if(interruptFlags & RX0IF) {
      // read from RX buffer 0
      message = CAN.ReadBuffer(RXB0);
    }
    if(interruptFlags & RX1IF) {
      // read from RX buffer 1
      message = CAN.ReadBuffer(RXB1);
      // (this is poor code as clearly if two messages are received then the second will overwrite the first)
    }
    if(interruptFlags & TX0IF) {
      // TX buffer 0 sent
    }
    if(interruptFlags & TX1IF) {
      // TX buffer 1 sent
    }
    if(interruptFlags & TX2IF) {
      // TX buffer 2 sent
    }
    if(interruptFlags & ERRIF) {
      // error handling code
    }
    if(interruptFlags & MERRF) {
      // error handling code
      // if TXBnCTRL.TXERR set then transmission error
      // if message is lost TXBnCTRL.MLOA will be set
    }
 }
  
  if(message.id>0) {
    // Print message
    Serial.print("ID: ");
    Serial.println(message.id,HEX);
    Serial.print("Extended: ");
    if(message.ide) {
      Serial.println("Yes");
    } else {
      Serial.println("No");
    }
    Serial.print("DLC: ");
    Serial.println(message.dlc,DEC);
    for(i=0;i<message.dlc;i++) {
      Serial.print(message.data[i],HEX);
      Serial.print(" ");
    }
    Serial.println();
    Serial.println();

    // Send out a return message for each one received
    // Simply increment message id and data bytes to show proper transmission
    // Note: Please see explanation at top of sketch. You might want to comment this out!
   // message.id++;
 // for(i=0;i<message.dlc;i++) {
  // message.data[i]++;
  // }
 // CAN.LoadBuffer(TXB0, message);
 // CAN.SendBuffer(TXB0);
  }
}