Crate socketcan_hal

SocketCAN support.

The Linux kernel supports using CAN-devices through a network-like API (see https://www.kernel.org/doc/Documentation/networking/can.txt). This crate allows easy access to this functionality without having to wrestle libc calls.

An introduction to CAN

The CAN bus was originally designed to allow microcontrollers inside a vehicle to communicate over a single shared bus. Messages called frames are multicast to all devices on the bus.

Every frame consists of an ID and a payload of up to 8 bytes. If two devices attempt to send a frame at the same time, the device with the higher ID will notice the conflict, stop sending and reattempt to sent its frame in the next time slot. This means that the lower the ID, the higher the priority. Since most devices have a limited buffer for outgoing frames, a single device with a high priority (== low ID) can block communication on that bus by sending messages too fast.

The Linux socketcan subsystem makes the CAN bus available as a regular networking device. Opening an network interface allows receiving all CAN messages received on it. A device CAN be opened multiple times, every client will receive all CAN frames simultaneously.

Similarly, CAN frames can be sent to the bus by multiple client simultaneously as well.

Hardware and more information

More information on CAN can be found on Wikipedia. When not running on an embedded platform with already integrated CAN components, Thomas Fischl’s USBtin (see section 2.4) is one of many ways to get started.

RawFd

Raw access to the underlying file descriptor and construction through is available through the AsRawFd, IntoRawFd and FromRawFd implementations.

Crate Features

Default

• netlink - Whether to include programmable CAN interface configuration capabilities based on netlink kernel communications. This brings in the neli library and its dependencies.

Non-default

• utils - Whether to build command-line utilities. This brings in additional dependencies like anyhow and clap

Modules

dump

candump format parsing

Structs

CanFilter

CanFilter

CanFrame

CanFrame

CanInterface

SocketCAN interface

CanSocket

A socket for a CAN device.

Enums

CanError

CanErrorDecodingFailure

Error decoding a CanError from a CanFrame.

CanSocketOpenError

Errors opening socket

ConstructionError

Error that occurs when creating CAN packets

Constants

EFF_FLAG

if set, indicate 29 bit extended format

EFF_MASK

valid bits in extended frame id

ERR_FLAG

error flag

ERR_MASK

valid bits in error frame

ERR_MASK_ALL

an error mask that will cause SocketCAN to report all errors

ERR_MASK_NONE

an error mask that will cause SocketCAN to silently drop all errors

RTR_FLAG

remote transmission request flag

SFF_MASK

valid bits in standard frame id

Traits

ShouldRetry

Check an error return value for timeouts.