SwiftCANLib

SwiftCANLib is a library used to process Controller Area Network (CAN) frames utilizing the Linux kernel open source library SOCKETCAN.
This library has been tested with Rapsbian Buster, arm32 & arm64, on a Raspberry Pi 4. It will not compile and run on macOS/iOS/iPadOS/tvOS because SOCKETCAN is not distributed on these platforms.

This is not an officially supported Google product.

How to add SwiftCANLib to your project

In your Package.swift file add the following dependency and add SwiftCANLib to all targets that will use the library:

https://github.com/leisurehound/swiftcanlib.git

Import SwiftCANLib in files where your project will interact with the CAN interface on your device

#import SwiftCANLib

Create a set of signals for the data parameters you’re interested in:

let speedSignal = CANCalibrations.Signal(name: "Speed",
                                            unit: "km/h",
                                            dataLength: 16, startBit: 32,
                                            endianness: .bigEndian,
                                            isSigned: false,
                                            offset: -100.0,
                                            gain: 0.01)
let rpmSignal = CANCalibrations.Signal(name: "Engine Speed",
                                            unit: "rpm",
                                            dataLength: 0, startBit: 16,
                                            endianness: .bigEndian,
                                            isSigned: false,
                                            offset: 0.0,
                                            gain: 1.0)

Add signals to a frame calibration:

let frame100Calibration = CANCalibrations.FrameDefinition(frameID: 0x100, signals: [speedSignal])
let frame120Calibration = CANCalibrations.FrameDefinition(frameID: 0x120, signals: [rpmSignal])

Add the frame calibrations to the CANCalibrations object:

let calibrations = CANCalibrations(frames: [frame100Calibration, frame120Calibration], delegate: self)

Create the CANInterface object, injecting the calibrations you’re interested in processing from that interface and start listening:

let primaryCAN = try? CANInterface(name: "can1", filters: [0x100,0x120], calibrations: calibrations)
primaryCAN?.startListening()

Create a delegate object that conforms the CANCalibrationsListenerDelegate and implement the processCalibratedData method:

func processCalibratedData(_ calibrations: CANCalibrations, calibratedData: CANCalibrations.CalibratedData) {

  for (signalName, datum) in calibratedData.signals {
    print("Received data for \(signalName) of value \(datum.value) \(datum.unit)")
  }

}

Thats it! This has been tested with Swift 5.4 on arm64 Raspberry Pi 4 and with Swift 5.1 on arm32 Raspberry Pi 3B.

SwiftCANLib performs its listening on each CAN interface on its own queue; you can direct SwiftCANLib to return data to you on an thread you specify, or it will default to calling the delegate on DispatchQueue.main.

Caveats

The library supports both little and big endian frames on big and little endian platforms. However, there are currently no big endian platforms that support Swift, thus running on a big endian platform is completely untested. Big and little endian frames on a little endian platform is supported and tested by unit tests.

Note that SwiftCANLib does not use SOCKETCAN directly. Swift currently will not link correctly against a CSocketCAN module on Linux thus a C language bridge module is utlized to make the SOCKETCAN calls.

SwiftCANLib will not compile and run on macOS/iOS/iPadOS/tvOS because SOCKETCAN is not distributed on these platforms.

Utlizing Combine for feeding CAN frames to client applications would be awesome. However Apple has not open sourced Combine thus it has not been ported to Linux and SwiftCANLib uses a simple delegate pattern for providing data the client application.

License

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this work except in compliance with the License.

GitHub

View Github