pi-can

This package is capable of controlling CAN BUS modules with SPI interface.
I used the MCP2515 CAN BUS module, but might be useful for other CAN modules.

This package is created according to this arduino library: https://github.com/Seeed-Studio/CAN_BUS_Shield

Installation

Firstly, you need to install Node.js. I am using node v12.16.1 and npm 6.14.3.
Follow this tutorial for installation: How to Install Node.js and npm on Raspberry Pi

Secondly, you need to create an npm project.

After that, you can install PI-CAN node module.
Use:

npm i pi-can

Finally, you need to enable SPI communication on the Pi.
Use sudo raspi-config and navigate to 5 Interfacing Options > SPI > Yes (enable)

Reboot your Pi and you can start to programming your CAN network.

Examples

Basics

const PiCan = require('pi-can');
 
const can = new PiCan('/dev/spidev0.0');
can.begin(PiCan.defs.CAN_500KBPS)
    .then(() => {
        console.log('INIT SUCCESS');
        // You can now use readMsg, sendMsg and others
    })
    .catch(() => {
        console.log('INIT FAILED');
    })

Reading data from CAN module

setInterval(async () => {
    let stat = await can.checkReceive();
    if (stat === PiCan.defs.CAN_MSGAVAIL) {
        can.readMsg()
            .then(data => console.log('Recv:', data))
            .catch(error => {
                console.log('error', error);
            })
    }
    if (stat === PiCan.defs.CAN_NOMSG) { }
}, 10);

Writing data to CAN module

// ID, Extended, RTR, Length, Data
can.sendMsg(123, false, false, 3, [1, 2, 3])
    .then(() => {
        console.log('SENT');
    })
    .catch(() => {
        console.log('Failed to send');
    })

Applying filters to a message

can.begin(PiCan.defs.CAN_500KBPS)
.then(() => can.setMask(0, false, 0x7ff))
.then(() => can.setMask(1, false, 0x7ff))
// You should set both masks. More detailes at API > setMask
.then(() => can.setFilter(0, false, 0xfa))
//.then(() => can.setFilter(0..5, Extended, Accepted_id))

Reading and writing to CAN module's GPIO

can.begin(PiCan.defs.CAN_500KBPS)
// You can set pinmodes like this:
.then(() => can.pinMode(PiCan.rxPin(0), PiCan.defs.MCP_PIN_OUT))
.then(() => can.pinMode(PiCan.rxPin(1), PiCan.defs.MCP_PIN_OUT))
.then(() => can.pinMode(PiCan.txPin(0), PiCan.defs.MCP_PIN_IN))
.then(() => can.pinMode(PiCan.txPin(1), PiCan.defs.MCP_PIN_IN))
.then(() => can.pinMode(PiCan.txPin(2), PiCan.defs.MCP_PIN_IN))
 
// Write to output
can.digitalWrite(PiCan.rxPin(0), true);
can.digitalWrite(PiCan.rxPin(1), false);
 
// Read from input
can.digitalRead(PiCan.txPin(0)).then(value=>console.log(value));
can.digitalRead(PiCan.txPin(1)).then(value=>console.log(value));
can.digitalRead(PiCan.txPin(2)).then(value=>console.log(value));
// You can also read written output value. Use rxPin with digitalRead.

IMPORTANT: TX is the input, RX is the output

API

new PiCan(spi, debug)

Creates a new instance of this module.

spi:

SPI device
Usually it is '/dev/spidev0.0' or '/dev/spidev0.1'.

debug:

true of false
If set to true, you will get logs in the console about the current state of the program.

begin(speedset, clockset)

Initializes the module, than set speed and clock.

speedset:

Any of these values:

PiCan.defs.CAN_5KBPS  
PiCan.defs.CAN_10KBPS  
PiCan.defs.CAN_20KBPS  
PiCan.defs.CAN_25KBPS  
PiCan.defs.CAN_31K25BPS  
PiCan.defs.CAN_33KBPS  
PiCan.defs.CAN_40KBPS  
PiCan.defs.CAN_50KBPS  
PiCan.defs.CAN_80KBPS  
PiCan.defs.CAN_83K3BPS  
PiCan.defs.CAN_95KBPS  
PiCan.defs.CAN_100KBPS  
PiCan.defs.CAN_125KBPS  
PiCan.defs.CAN_200KBPS  
PiCan.defs.CAN_250KBPS  
PiCan.defs.CAN_500KBPS  
PiCan.defs.CAN_666KBPS  
PiCan.defs.CAN_1000KBPS  

This speed needs to be consistent between the CAN nodes.
You need to set this, there is no default value.

clockset:

MCP_16MHz (default) or
MCP_8MHz

RETURN

Promise

checkReceive()

Returns the status of the receive buffers.

RETURN

Promise
If fulfilled the return value can be PiCan.defs.CAN_MSGAVAIL or PiCan.defs.CAN_NOMSG

readMsg()

Returns a message from the receive buffers.

RETURN

Promise
If fulfilled the return value is an object like this:

{
  id: number, // The ID of the message
  ext: boolean, // Extended frame
  rtr: boolean, // Remote transmission request
  size: number, // Message length
  data: number[], // Message data
}
// Message data is an empty array if RTR received

sendMsg(id, ext, rtrBit, len, buf)

Sends a message to the CAN network.

id

The ID of the message.
Accepts number value.

ext

True if you want to send an extended frame.
Accepts boolean value.

rtrBit

True if you want to send a remote request.
Accepts boolean value.

len

The length of the message
Accepts number value from 0 to 8.

buf

The content of the message
Accepts an array of numbers. Needs to contain between 0 and 8 numbers.
If rtrBit === true, this shuld be an empty array.

RETURN

Promise
If rejected the return value can be PiCan.defs.CAN_GETTXBFTIMEOUT

trySendMsg(id, ext, rtrBit, len, buf, iTxBuf) {

Tries to send a message through a specified transfer buffer.

iTxBuf

The transfer buffer's number.
Accepts 0, 1 or 2

See other parameters above, at the sendMsg description.

sleep()

Takes the module into sleep mode.

RETURN

Promise

wake()

Wakes up the module

RETURN

Promise

setFilter(num, ext, ulData)

Sets a filter to the recived messages.
You can use up to 6 filters (from 0 to 5)

num

The number of the filter.
Number between 0 and 5

ext

Extended ID, boolean

ulData

The accepted ID, number

RETURN

Promise

getFilter(num)

Gets a filter value.

num

The number of the filter

RETURN

An object like this:

{
  id: number, // Filter ID
  ext: number // Is ID extended
}

setMask(num, ext, ulData)

Sets a mask to the filters.
There are two different masks. They are for the two different receive buffers.
You should set the same mask for each receive buffer.
The message will be received, if this logic returns true:

(RECEIVED_ID & MASK) == (FILTER & MASK)
// & means bitwise and.

So, you can turn off masks and filters, if both masks are set to 0.

num

The number of the mask.
Number 0 or 1

ext

Extended ID, boolean

ulData

The applied mask on the filter, number

RETURN

Promise

getMask(num)

Gets a mask value.

Parameters: Same as setFilter.

pinMode(pin, mode)

Sets pin mode on GPIO

pin

Any of these values:

PiCan.rxPin(0)
PiCan.rxPin(1)
PiCan.txPin(0)
PiCan.txPin(1)
PiCan.txPin(2)

mode

Any of these values:

PiCan.defs.MCP_PIN_HIZ
PiCan.defs.MCP_PIN_INT
PiCan.defs.MCP_PIN_OUT
PiCan.defs.MCP_PIN_IN

MCP_PIN_IN cannot be applied to RX pins.
MCP_PIN_HIZ and MCP_PIN_IN cannot be applied to TX pins.

RETURN

Promise

digitalWrite(pin, mode)

Writes data to a GPIO output (to RX pin)

pin

PiCan.rxPin(0) or PiCan.rxPin(1)

mode

true or false

RETURN

Promise

digitalRead(pin)

Reads data from a GPIO input (from TX pin)

pin

Any of these values

PiCan.rxPin(0)
PiCan.rxPin(1)
PiCan.txPin(0)
PiCan.txPin(1)
PiCan.txPin(2)

RETURN

Promise
If fulfilled the return can be true or false

static rxPin(pin)

Gets RX GPIO pin.

pin

0 or 1

RETURN

PiCan.defs.MCP_RX0BF or PiCan.defs.MCP_RX1BF

static txPin(pin)

Gets TX GPIO pin.

pin

0, 1 or 2

RETURN

PiCan.defs.MCP_TX0RTS, PiCan.defs.MCP_TX1RTS or PiCan.defs.MCP_TX2RTS

static defs

PiCan.defs contains all definitions for this module.

Donation

If this project was useful for you, you can give me a cup of coffee :)
Thank You!