MCP2515 Library example

CANTest.ino

/*
  MCP2515 CAN Interface Using SPI
  
  Author: David Harding
  
  Created: 11/08/2010
  Modified: 6/26/12 by RechargeCar Inc.
  
  For further information see:
  
  http://ww1.microchip.com/downloads/en/DeviceDoc/21801e.pdf
  http://en.wikipedia.org/wiki/CAN_bus

  The MCP2515 Library files also contain important information.
  
  This sketch is configured to work with the 'Macchina' Automotive Interface board 
  manufactured by RechargeCar Inc. CS_PIN and INT_PIN are specific to this board.
  
  This sketch shows the most basic of steps to send and receive CAN messages.
  
  NOTE!!!  If you use this sketch to test on a live system I suggest that you comment out the
  send messages lines unless you are certain that they will have no detrimental effect! 


  This example code is in the public domain.
  
*/

#include <SPI.h> // Arduino SPI Library
#include <MCP2515.h>

// Pin definitions specific to how the MCP2515 is wired up.
#define CS_PIN    85
#define RESET_PIN  7
#define INT_PIN    84

// Create CAN object with pins as defined
MCP2515 CAN(CS_PIN, RESET_PIN, INT_PIN);

void setup() {
  Serial.begin(115200);
  
  Serial.println("Initializing ...");

  // Set up SPI Communication
  // dataMode can be SPI_MODE0 or SPI_MODE3 only for MCP2515
  SPI.setClockDivider(SPI_CLOCK_DIV2);
  SPI.setDataMode(SPI_MODE0);
  SPI.setBitOrder(MSBFIRST);
  SPI.begin();
  
  // Initialise MCP2515 CAN controller at the specified speed and clock frequency
  // In this case 125kbps with a 16MHz oscillator
  // (Note:  This is the oscillator attached to the MCP2515, not the Arduino oscillaltor)
  if(CAN.Init(250,16))
  {
    Serial.println("MCP2515 Init OK ...");
  } else {
    Serial.println("MCP2515 Init Failed ...");
  }

  Serial.println("Ready ...");
}

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);
  }
}

nice

Am in initial stages of introducing myself to the CANBUS to use in a bi-directional DIY application. Last couple of days' discoveries of available (and bug-free examples) has been disappointing. Thank you for explaining this so well and providing the resources. It's the best I've seen and will likely form the foundation of my DIY project. Thanks a million !