Categorygithub.com/tech-pi/can
modulepackage
0.0.2
Repository: https://github.com/tech-pi/can.git
Documentation: pkg.go.dev
Overview
Versions
1
Dependencies
9
Dependents
1
Files
356 SLOC

# README

can

can provides an interface to a CAN bus to read and write frames. The library is based on the SocketCAN network stack on Linux.

Hardware

I'm using a Raspberry Pi 2 Model B and PiCAN2 CAN-Bus board for Raspberry Pi 2 to connect to a CAN bus.

Software

The Raspberry Pi runs Raspbian.

Configuration

Update /boot/config.txt with

dtparam=spi=on 
dtoverlay=mcp2515-can0-overlay,oscillator=16000000,interrupt=25 
dtoverlay=spi-bcm2835-overlay

and reboot.

After phyiscally connecting to the CAN bus, you have to set up the can network interface for a specific bitrate, i.e. 50 kB

sudo ip link set can0 up type can bitrate 50000

Running ifconfig should now include the can0 interface.

Test your configuration

You should test if you actually receive data from the CAN bus. You can either use the candump tool from the can-utils or a simple reimplementation under cmd/candump.go.

Either way you will see something like this

> go run $GOSRC/github.com/brutella/can/cmd/candump.go -if can0

can0 100  [6] 20 83 0C 00 67 29        ' ...g)'
can0 701  [1] 05                       '.'

Usage

Setup the CAN bus

bus, _ := can.NewBusForInterfaceWithName("can0")
bus.ConnectAndPublish()

Send a CAN frame

frm := can.Frame{
	ID:     0x701,
	Length: 1,
	Flags:  0,
	Res0:   0,
	Res1:   0,
	Data:   [8]uint8{0x05},
}

bus.Publish(frm)

Receive a CAN frame

bus.SubscribeFunc(handleCANFrame)

func handleCANFrame(frm can.Frame) {    
    ...
}

There is more to learn from the documentation.

Contact

Matthias Hochgatterer

Github: https://github.com/brutella

Twitter: https://twitter.com/brutella

License

can is available under the MIT license. See the LICENSE file for more info.

# Packages

This program logs can frames to the console similar to candump from can-utils[1].

# Functions

Marshal returns the byte encoding of frm.
NewBus returns a new CAN bus.
NewBusForInterfaceWithName returns a bus from the network interface with name ifaceName.
NewEchoReadWriteCloser returns a ReadWriteCloser which echoes received bytes.
NewHandler returns a new handler which calls fn when a frame is received.
NewReadWriteCloser returns a ReadWriteCloser for an `io.ReadWriteCloser`.
No description provided by the author
No description provided by the author
Unmarshal parses the bytes b and stores the result in the value pointed to by frm.
Wait returns a channel, which receives a frame or an error, if the frame with the expected id didn't arrive on time.

# Constants

No description provided by the author
MaskEff is used to extract the eff flag (0 = standard frame, 1 = extended frame) from the frame ID.
MaskErr is used to extract the the error flag (0 = data frame, 1 = error message) from the frame ID.
MaskIDEff is used to extract the valid 29-bit CAN identifier bits from the frame ID of an extended frame format.
MaskIDSff is used to extract the valid 11-bit CAN identifier bits from the frame ID of a standard frame format.
MaskRtr is used to extract the rtr flag (1 = rtr frame) from the frame ID.
MaxExtFrameDataLength defines the max length of an CAN extended data frame defined in ISO ISO 11898-7.
MaxFrameDataLength defines the max length of a CAN data frame defined in ISO 11898-1.

# Structs

Bus represents the CAN bus.
Frame represents a standard CAN data frame.
A WaitResponse encapsulates the response of waiting for a frame.

# Interfaces

The Handler interfaces defines a method to receive a frame.
The Reader interface extends the `io.Reader` interface by method to read a frame.
The ReadWriteCloser interface combines the Reader and Writer and `io.Closer` interface.
The Writer interface extends the `io.Writer` interface by method to write a frame.

# Type aliases

HandlerFunc defines the function type to handle a frame.