Mcp25xxx device family - CAN bus

This binding is currently not finished. Please consider contributing to help us finish it.

The MCP25XXX is a stand-alone CAN controller and includes features like faster throughput, databyte filtering, and support for time-triggered protocols.

Documentation

MCP25XXX devices contain different markings to distinguish features like interfacing, packaging, and temperature ratings. For example, MCP25625 contains a CAN transceiver. Please review specific datasheet for more information.

Usage

Important: make sure you properly setup the SPI pins especially for ESP32 before creating the SpiDevice, make sure you install the nanoFramework.Hardware.ESP32 nuget:

//////////////////////////////////////////////////////////////////////
// when connecting to an ESP32 device, need to configure the SPI GPIOs
// used for the bus
Configuration.SetPinFunction(21, DeviceFunction.SPI1_MOSI);
Configuration.SetPinFunction(22, DeviceFunction.SPI1_MISO);
Configuration.SetPinFunction(23, DeviceFunction.SPI1_CLOCK);
// Make sure as well you are using the right chip select

For other devices like STM32, please make sure you're using the preset pins for the SPI bus you want to use. The chip select can as well be pre setup.

You can create a Mcp25625 device like this:

SpiConnectionSettings spiConnectionSettings = new(1, 42);
SpiDevice spiDevice = SpiDevice.Create(spiConnectionSettings);
Mcp25625 mcp25xxx = new Mcp25625(spiDevice);

Read all the registers

You can read all the registers like this:

Debug.WriteLine("Read Instruction for All Registers");
Array addresses = Enum.GetValues(typeof(Address));

foreach (Address address in addresses)
{
    byte addressData = mcp25xxx.Read(address);
    Debug.WriteLine($"0x{(byte)address:X2} - {address,-10}: 0x{addressData:X2}");
}

to read a single register, just use the Address enum.

RX Status

The RX status is available like this:

Debug.WriteLine("Rx Status Instruction");
RxStatusResponse rxStatusResponse = mcp25xxx.RxStatus();
Debug.WriteLine($"Value: 0x{rxStatusResponse.ToByte():X2}");
Debug.WriteLine($"Filter Match: {rxStatusResponse.FilterMatch}");
Debug.WriteLine($"Message Type Received: {rxStatusResponse.MessageTypeReceived}");
Debug.WriteLine($"Received Message: {rxStatusResponse.ReceivedMessage}");

Read Status

The Read status is available like this:

Debug.WriteLine("Read Status Instruction");
ReadStatusResponse readStatusResponse = mcp25xxx.ReadStatus();
Debug.WriteLine($"Value: 0x{readStatusResponse:X2}");
Debug.WriteLine($"Rx0If: {readStatusResponse.HasFlag(ReadStatusResponse.Rx0If)}");
Debug.WriteLine($"Rx1If: {readStatusResponse.HasFlag(ReadStatusResponse.Rx1If)}");
Debug.WriteLine($"Tx0Req: {readStatusResponse.HasFlag(ReadStatusResponse.Tx0Req)}");
Debug.WriteLine($"Tx0If: {readStatusResponse.HasFlag(ReadStatusResponse.Tx0If)}");
Debug.WriteLine($"Tx0Req: {readStatusResponse.HasFlag(ReadStatusResponse.Tx0Req)}");
Debug.WriteLine($"Tx1If: {readStatusResponse.HasFlag(ReadStatusResponse.Tx1If)}");
Debug.WriteLine($"Tx1Req: {readStatusResponse.HasFlag(ReadStatusResponse.Tx1Req)}");
Debug.WriteLine($"Tx2Req: {readStatusResponse.HasFlag(ReadStatusResponse.Tx2Req)}");
Debug.WriteLine($"Tx2If: {readStatusResponse.HasFlag(ReadStatusResponse.Tx2If)}");

Transmit a message

You can transmit a message like this:

Debug.WriteLine("Transmit Message");

mcp25xxx.WriteByte(
    new CanCtrl(CanCtrl.PinPrescaler.ClockDivideBy8,
        false,
        false,
        false,
        OperationMode.NormalOperation));

byte[] data = new byte[] { 0b0000_0001, 0b0010_0011, 0b0100_0101, 0b0110_0111, 0b1000_1001 };

mcp25xxx.Write(
    Address.TxB0Sidh,
    new byte[]
    {
        new TxBxSidh(0, 0b0000_1001).ToByte(), new TxBxSidl(0, 0b001, false, 0b00).ToByte(),
        new TxBxEid8(0, 0b0000_0000).ToByte(), new TxBxEid0(0, 0b0000_0000).ToByte(),
        new TxBxDlc(0, data.Length, false).ToByte()
    });

mcp25xxx.Write(Address.TxB0D0, data);

// Send with TxB0 buffer.
mcp25xxx.RequestToSend(true, false, false);
cp25xxx.RequestToSend(false, false, true);

Note: You will find detailed way of using this binding in the sample file

Binding Notes

More details will be added in future PR once core CAN classes/interfaces are determined.