m2m-can

m2m-can

m2m-can is a basic can-bus library based on SocketCAN using a simple and easy API. Open and connect the can interface to the can-bus. Once connected, your device can start sending or receiving data to/from the can-bus.

• Supported devices
• Node.js version requirement
• Setup Raspberry Pi to use can-bus (using MCP2515 CAN module)
• Installation
• Quick Tour

Supported devices

• Raspberry Pi Models: B+, 2, 3, Zero & Zero W, Compute Module 3, 3B+, 3A+, 4B (generally all 40-pin models)

Node.js version requirement

• Node.js versions: 10.x, 11.x, 12.x, 14.x, 16.x. Ideally the latest LTS version.

Installation

$ npm install m2m-can

Raspberry Pi peripheral access (GPIO, I2C, SPI and PWM).

For projects requiring raspberry pi peripheral access such as GPIO, I2C, SPI and PWM, you will need to install array-gpio module.

$ npm install array-gpio

Quick Tour

On can-bus communication, each device should either be sending or receiving data to/from other devices on the network but not both.

Master application

'use strict';

const can = require('m2m-can');

let temp = null, random = null;

/* temperature can-bus device frame id */
const temp_id = '025';

/* random can-bus device frame id */
const random_id = '035';

/* master can-bus frame id or can node id */
const master_id = '00C';

/* open can0 interface, set bitrate to 500000 Hz */
// defaults to txqueuelen = 1000, rs = 100
can.open('can0', 500000, function(err){
  if(err) return console.error('can0 interface open error', err.message);
  // if can0 was opened successfully, you'll see an output - ip link set can0 up with txqueuelen 1000 and bitrate 500000 - success

  // read all frame data from CAN bus from all frame id's sending data to CAN bus
  can.read('can0', function(err, fdata){
    if(err) return console.log('can read error', err.message);
    console.log('read all frame data', fdata);
  });

  // read only random frame data from CAN bus using the random_id
  can.read('can0', {id:random_id}, function(err, fdata){
    if(err) return console.log('can read error', err.message);
    console.log('can-random frame data', fdata);
    // { id: '035', len: 3, data: [ 12, 52 ], filter: '035', change: true }   
    // data[0] - integer value
    // data[1] - integer value    
    random = fdata.data[0].toString() + fdata.data[1].toString();
    console.log('random data', random); // 1252
  });

  // read only temperature frame data from CAN bus using the temp_id
  can.read('can0', {id:temp_id} , function(err, fdata){
    if(err) return console.log('can read error', err.message);
    console.log('can-temp frame data', fdata);
    // { id: '025', len: 2, data: [ 18, 94 ], filter: '025', change: true }
    // data[0] - integer value
    // data[1] - fractional value    
    temp = fdata.data[0] + '.' + fdata.data[1];
    console.log('temperature data', temp); // 18.94
  });
});

Slave1 application

'use strict';

const can = require('m2m-can');
const r = require('array-gpio');

/* using the built-in MCP9808 chip library for capturing temperature data using i2c */
let i2c =  require('./node_modules/array-gpio/examples/i2c9808.js');

/* setup gpio output pins for led status indicator using array-gpio */
let led1 = r.out(33); // set gpio output pin 33 for can device status led
let led2 = r.out(35); // set gpio output pin 35 for data change status led

/* can-bus temperature device id */
const temp_id = '025';

can.open('can0', 500000, function(err){
  if(err) return console.error('can0 interface open error', err.message);

  led1.on();
  led2.off();

  // watch for changes in your data
  can.watch('can0', {id:temp_id}, (err, data) => { // watch interval defaults to 100 ms
    if(err) return console.error('can watch error', err.message);

    // set payload property to your data source
    data.payload = i2c.getTemp();

    // if temp data value has changed, send data to CAN bus from temp_id
    if(data.change === true){
      console.log('send temp data', data.payload);
      led2.pulse(200);
      can.send('can0', temp_id, data.payload);
    }
    else{
      console.log('no data change');
    }
  });
});

Slave2 application

'use strict';

const can = require('m2m-can');
const r = require('array-gpio');

/* setup can bus device led status indicator using array-gpio */
let led1 = r.out(33); // can device status
let led2 = r.out(35); // data change status

// can-bus device random id
const random_id = '035';

can.open('can0', 500000, function(err){
  if(err) return console.error('can0 interface open error', err.message);

    led1.on();
    led2.off();

    can.watch('can0', {id:random_id}, (err, data) => {
       if(err) return console.error('can watch error', err.message);

       data.payload = 1010 + Math.floor(( Math.random() * 200) + 100);

       // if random value has changed, send data to CAN bus from random_id
       // since a new value will be generated everytime, it will always send data to CAN bus   
       if(data.change){
         console.log('send random data', data.payload);
         can.send('can0', random_id, data.payload);
         led2.pulse(200);
       }
       else{
         console.log('no data change');
       }
    });
});

Can-bus setup

Pin Connection

RPI GPIO Header         MCP2515 CAN Module

PIN  NAME              PIN

#01   3.3V  ------------------  VCC

#06   GND  -----------------  GND

#19   SPI_MOSI  ----------  SI

#21   SPI_MISO  ----------  SO

#22   GPIO25  -------------  INT

#23   SPI_SCLK  ----------  SCK/CLK

#24   SPI_CE0  ------------  CS

• Open the Raspberry Pi config.txt file using an editor.

$ sudo mousepad /boot/config.txt

  or

$ sudo leafpad /boot/config.txt

• Uncomment the following section to enable SPI.

dtparam=spi=on

• Add the following as additional SPI setup.

dtoverlay=mcp2515-can0,oscillator=16000000,interrupt=25

• Comment the following section. This is not needed.

# dtoverlay=spi0-hw-cs

• Save the config.txt file. Reboot the Raspberry Pi.

• Verify the SPI configuration. The CAN module should be initialized.

$ dmesg | grep -i spi

  The result will look like as shown below.

[    8.544607] mcp251x spi0.0 can0: MCP2515 successfully initialized.

  By the same command you can check the CAN module if it was started by default:

$ dmesg | grep -i can

  The result will look like as shown below.

[    9.793497] CAN device driver interface
[    9.819174] mcp251x spi0.0 can0: MCP2515 successfully initialized.
[  271.563711] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready
[  271.695497] can: controller area network core
[  271.711043] can: raw protocol

  If for any reason this is not the case, you can add the CAN module at system start:

$ sudo nano /etc/modules

  Add "can" in a new line, save the file and reboot.

Optional additional CAN utilities.

• Install Linux can utility for SocketCAN (https://github.com/linux-can/can-utils).

$ sudo apt-get install can-utils

• Set the clock speed.

$ sudo ip link set can0 up type can bitrate 500000

  If the device is busy as shown below:

$ RTNETLINK answers: Device or resource busy

  Shutdown the CAN interface as shown below:

$ sudo ifconfig can0 down

  And then restart it as shown below:

$ sudo ifconfig can0 up

• Listen for any data in the CAN bus.

$ candump any

• Send some data to the CAN bus.

$ cansend can0 111#FF

• Below are some examples.

  Wrong CAN-frame format! Try:

<can_id>#{R|data}          for CAN 2.0 frames
<can_id>##<flags>{data}    for CAN FD frames

<can_id> can have 3 (SFF) or 8 (EFF) hex chars
{data} has 0..8 (0..64 CAN FD) ASCII hex-values (optionally separated by '.')
<flags> a single ASCII Hex value (0 .. F) which defines canfd_frame.flags

e.g. 5A1#11.2233.44556677.88 / 123#DEADBEEF / 5AA# / 123##1 / 213##311
     1F334455#1122334455667788 / 123#R for remote transmission request.

Links

can-utils https://github.com/linux-can/can-utils