Crate socketcan

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.

• dump - Whether to include candump parsing capabilities.

Non-default

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

• tokio - Include support for async/await using tokio.

• async-io - Include support for async/await using async-io This will work with any runtime that uses async_io, including async-std and smol.

• async-std - Include support for async/await using async-io with a submodule aliased for async-std and examples for that runtime.

• smol - Include support for async/await using async-io with a submodule aliased for smol and examples for that runtime.

Re-exports

• pub use errors::CanError;
• pub use errors::CanErrorDecodingFailure;
• pub use errors::ConstructionError;
• pub use errors::Error;
• pub use errors::Result;
• pub use frame::CanAnyFrame;
• pub use frame::CanDataFrame;
• pub use frame::CanErrorFrame;
• pub use frame::CanFdFrame;
• pub use frame::CanFrame;
• pub use frame::CanRemoteFrame;
• pub use frame::Frame;
• pub use socket::CanAddr;
• pub use socket::CanFdSocket;
• pub use socket::CanFilter;
• pub use socket::CanSocket;
• pub use socket::ShouldRetry;
• pub use socket::Socket;
• pub use socket::SocketOptions;
• pub use nl::CanCtrlMode;
• pub use nl::CanInterface;
• pub use embedded_can;

Modules

• dump
  candump format parsing
• errors
  CAN bus errors.
• frame
  CAN bus frames.
• nl
  CAN Netlink access
• socket
  Implementation of sockets for CANbus 2.0 and FD for SocketCAN on Linux.

Structs

• ExtendedId
  Extended 29-bit CAN Identifier (0..=1FFF_FFFF).
• StandardId
  Standard 11-bit CAN Identifier (0..=0x7FF).

Enums

• Id
  A CAN Identifier (standard or extended).

Traits

• BlockingCan
  A blocking CAN interface that is able to transmit and receive frames.
• EmbeddedFrame
  A CAN2.0 Frame
• NonBlockingCan
  A CAN interface that is able to transmit and receive frames.