CAN BUS Shield for Arduino: Example Code for Three Node CAN Network

The doc post offers example code for a three-node CAN network using Arduino, detailing nodes' roles in data transmission and reception, enhancing understanding of network communication.

Hardware Preparation

Item	SKU / Model	Qty	Link
Arduino UNO	Arduino UNO	3	Purchase
CAN-BUS Shield V2	DFR0370	3	Purchase
Dupont Cable	—	6	—

Software Preparation

Item	Version / Description	Link
Arduino IDE	v1.6.5	Download
CAN-BUS Shield Library	MCP2515 (v2.0)	GitHub
Installation Tutorial	Arduino IDE Library Installation	View Guide

Wiring Diagram

dfr0370 three

Other Preparation Work

Connect CAN-H and CAN-L lines between all three nodes.
Configure each node's mask and filter registers as per the code.

Sample Code

Node1 Code

Same as Specified ID Data Frame Receiver Code.

Node2 Code

#include <SPI.h>
#include "df_can.h"
const int SPI_CS_PIN =10;
MCPCAN CAN(SPI_CS_PIN);
unsigned char flagRecv=0;
unsigned char len=0;
unsigned char buf[8];
char str[20];
void setup()
{
    Serial.begin(115200);
    int count=50;
    do {
        CAN.init();
        CAN.init_Mask(MCP_RXM0,0,0x3ff);
        CAN.init_Mask(MCP_RXM1,0,0x3ff);
        CAN.init_Filter(MCP_RXF5,0,0x09);
        if(CAN_OK == CAN.begin(CAN_500KBPS))
        {
            Serial.println("DFROBOT's CAN BUS Shield init ok!");
            break;
        }
        else
        {
            Serial.println("DFROBOT's CAN BUS Shield init fail");
            Serial.println("Please Init CAN BUS Shield again");
            delay(100);
            if(count<=1) Serial.println("Please give up trying!, trying is useless!");
        }
    }while(count--);
    attachInterrupt(0, MCP2515_ISR, FALLING);
}

void MCP2515_ISR()
{
    flagRecv=1;
}

unsigned char data[] = "node 2";
void loop()
{
    if(flagRecv)
    {
        flagRecv=0;
        CAN.readMsgBuf(&len, buf);
        Serial.println("\r\n------------------------------------------------------------------");
        Serial.print("Get Data From id: ");
        Serial.println(CAN.getCanId());
        for(int i=0; i<len; i++)
        {
            Serial.print(buf[i]);
            Serial.print("\t");
        }
        Serial.println();
    }
    CAN.sendMsgBuf(0x08,0,sizeof(data),data);
    delay(1000);
}

Node3 Code

#include <SPI.h>
#include "df_can.h"
const int SPI_CS_PIN =10;
MCPCAN CAN(SPI_CS_PIN);
unsigned char flagRecv=0;
unsigned char len=0;
unsigned char buf[8];
char str[20];
void setup()
{
    Serial.begin(115200);
    int count=50;
    do {
        CAN.init();
        CAN.init_Mask(MCP_RXM0,0,0x3ff);
        CAN.init_Mask(MCP_RXM1,0,0x3ff);
        CAN.init_Filter(MCP_RXF5,0,0x08);
        if(CAN_OK == CAN.begin(CAN_500KBPS))
        {
            Serial.println("DFROBOT's CAN BUS Shield init ok!");
            break;
        }
        else
        {
            Serial.println("DFROBOT's CAN BUS Shield init fail");
            Serial.println("Please Init CAN BUS Shield again");
            delay(100);
            if(count<=1) Serial.println("Please give up trying!, trying is useless!");
        }
    }while(count--);
    attachInterrupt(0, MCP2515_ISR, FALLING);
}

void MCP2515_ISR()
{
    flagRecv=1;
}

unsigned char data[] = "node3";
void loop()
{
    if(flagRecv)
    {
        flagRecv=0;
        CAN.readMsgBuf(&len, buf);
        Serial.println("\r\n------------------------------------------------------------------");
        Serial.print("Get Data From id: ");
        Serial.println(CAN.getCanId());
        for(int i=0; i<len; i++)
        {
            Serial.print(buf[i]);
            Serial.print("\t");
        }
        Serial.println();
    }
    CAN.sendMsgBuf(0x09,0,sizeof(data),data);
    delay(1000);
}

Result

Each node's serial port output shows data from allowed IDs:

DFR0370

Additional Information

This example shows how to build a multi-node CAN network with selective data transmission and reception.

Example Code for Arduino-Three Node CAN Network