Working with USB devices in .NET

Question

Using .Net (C#), how can you work with USB devices?

How can you detect USB events (connections/disconnections) and how do you communicate with devices (read/write).

Answer 1

USB devices usually fall in to two categories: Hid, and USB. A USB device may or may not be a Hid device and vice versa. Hid is usually a little easier to work with than direct USB. Different platforms have different APIs for dealing with both USB and Hid.

Here is documentation for UWP:

USB: https://docs.microsoft.com/en-us/windows-hardware/drivers/usbcon/how-to-connect-to-a-usb-device--uwp-app-

Hid: https://docs.microsoft.com/en-us/uwp/api/windows.devices.humaninterfacedevice

Here is the documentation for Android: https://developer.xamarin.com/api/namespace/Android.Hardware.Usb/

Here are two classes for dealing with USB/Hid at the raw Windows API level:

https://github.com/MelbourneDeveloper/Device.Net/blob/master/src/Hid.Net/Windows/HidAPICalls.cs

public static class HidAPICalls 
{
    #region Constants
    private const int DigcfDeviceinterface = 16;
    private const int DigcfPresent = 2;
    private const uint FileShareRead = 1;
    private const uint FileShareWrite = 2;
    private const uint GenericRead = 2147483648;
    private const uint GenericWrite = 1073741824;
    private const uint OpenExisting = 3;
    private const int HIDP_STATUS_SUCCESS = 0x110000;
    private const int HIDP_STATUS_INVALID_PREPARSED_DATA = -0x3FEF0000;
    #endregion

    #region API Calls

    [DllImport("hid.dll", SetLastError = true)]
    private static extern bool HidD_GetPreparsedData(SafeFileHandle hidDeviceObject, out IntPtr pointerToPreparsedData);

    [DllImport("hid.dll", SetLastError = true, CallingConvention = CallingConvention.StdCall)]
    private static extern bool HidD_GetManufacturerString(SafeFileHandle hidDeviceObject, IntPtr pointerToBuffer, uint bufferLength);

    [DllImport("hid.dll", SetLastError = true, CallingConvention = CallingConvention.StdCall)]
    private static extern bool HidD_GetProductString(SafeFileHandle hidDeviceObject, IntPtr pointerToBuffer, uint bufferLength);

    [DllImport("hid.dll", SetLastError = true, CallingConvention = CallingConvention.StdCall)]
    private static extern bool HidD_GetSerialNumberString(SafeFileHandle hidDeviceObject, IntPtr pointerToBuffer, uint bufferLength);

    [DllImport("hid.dll", SetLastError = true)]
    private static extern int HidP_GetCaps(IntPtr pointerToPreparsedData, out HidCollectionCapabilities hidCollectionCapabilities);

    [DllImport("hid.dll", SetLastError = true)]
    private static extern bool HidD_GetAttributes(SafeFileHandle hidDeviceObject, out HidAttributes attributes);

    [DllImport("hid.dll", SetLastError = true)]
    private static extern bool HidD_FreePreparsedData(ref IntPtr pointerToPreparsedData);

    [DllImport("hid.dll", SetLastError = true)]
    private static extern void HidD_GetHidGuid(ref Guid hidGuid);

    private delegate bool GetString(SafeFileHandle hidDeviceObject, IntPtr pointerToBuffer, uint bufferLength);

    #endregion

    #region Helper Methods

    #region Public Methods
    public static HidAttributes GetHidAttributes(SafeFileHandle safeFileHandle)
    {
        var isSuccess = HidD_GetAttributes(safeFileHandle, out var hidAttributes);
        WindowsDeviceBase.HandleError(isSuccess, "Could not get Hid Attributes");
        return hidAttributes;
    }

    public static HidCollectionCapabilities GetHidCapabilities(SafeFileHandle readSafeFileHandle)
    {
        var isSuccess = HidD_GetPreparsedData(readSafeFileHandle, out var pointerToPreParsedData);
        WindowsDeviceBase.HandleError(isSuccess, "Could not get pre parsed data");

        var result = HidP_GetCaps(pointerToPreParsedData, out var hidCollectionCapabilities);
        if (result != HIDP_STATUS_SUCCESS)
        {
            throw new Exception($"Could not get Hid capabilities. Return code: {result}");
        }

        isSuccess = HidD_FreePreparsedData(ref pointerToPreParsedData);
        WindowsDeviceBase.HandleError(isSuccess, "Could not release handle for getting Hid capabilities");

        return hidCollectionCapabilities;
    }

    public static string GetManufacturer(SafeFileHandle safeFileHandle)
    {
        return GetHidString(safeFileHandle, HidD_GetManufacturerString);
    }

    public static string GetProduct(SafeFileHandle safeFileHandle)
    {
        return GetHidString(safeFileHandle, HidD_GetProductString);
    }

    public static string GetSerialNumber(SafeFileHandle safeFileHandle)
    {
        return GetHidString(safeFileHandle, HidD_GetSerialNumberString);
    }
    #endregion

    #region Private Static Methods
    private static string GetHidString(SafeFileHandle safeFileHandle, GetString getString)
    {
        var pointerToBuffer = Marshal.AllocHGlobal(126);
        var isSuccess = getString(safeFileHandle, pointerToBuffer, 126);
        Marshal.FreeHGlobal(pointerToBuffer);
        WindowsDeviceBase.HandleError(isSuccess, "Could not get Hid string");
        return Marshal.PtrToStringUni(pointerToBuffer);     
    }
    #endregion

    #endregion

}

https://github.com/MelbourneDeveloper/Device.Net/blob/master/src/Usb.Net/Windows/WinUsbApiCalls.cs

public static partial class WinUsbApiCalls
{
    #region Constants
    public const int EnglishLanguageID = 1033;
    public const uint DEVICE_SPEED = 1;
    public const byte USB_ENDPOINT_DIRECTION_MASK = 0X80;
    public const int WritePipeId = 0x80;

    /// 

    /// Not sure where this constant is defined...
    /// 
    public const int DEFAULT_DESCRIPTOR_TYPE = 0x01;
    public const int USB_STRING_DESCRIPTOR_TYPE = 0x03;
    #endregion

    #region API Calls
    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_ControlTransfer(IntPtr InterfaceHandle, WINUSB_SETUP_PACKET SetupPacket, byte[] Buffer, uint BufferLength, ref uint LengthTransferred, IntPtr Overlapped);

    [DllImport("winusb.dll", SetLastError = true, CharSet = CharSet.Auto)]
    public static extern bool WinUsb_GetAssociatedInterface(SafeFileHandle InterfaceHandle, byte AssociatedInterfaceIndex, out SafeFileHandle AssociatedInterfaceHandle);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_GetDescriptor(SafeFileHandle InterfaceHandle, byte DescriptorType, byte Index, ushort LanguageID, out USB_DEVICE_DESCRIPTOR deviceDesc, uint BufferLength, out uint LengthTransfered);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_GetDescriptor(SafeFileHandle InterfaceHandle, byte DescriptorType, byte Index, UInt16 LanguageID, byte[] Buffer, UInt32 BufferLength, out UInt32 LengthTransfered);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_Free(SafeFileHandle InterfaceHandle);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_Initialize(SafeFileHandle DeviceHandle, out SafeFileHandle InterfaceHandle);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_QueryDeviceInformation(IntPtr InterfaceHandle, uint InformationType, ref uint BufferLength, ref byte Buffer);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_QueryInterfaceSettings(SafeFileHandle InterfaceHandle, byte AlternateInterfaceNumber, out USB_INTERFACE_DESCRIPTOR UsbAltInterfaceDescriptor);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_QueryPipe(SafeFileHandle InterfaceHandle, byte AlternateInterfaceNumber, byte PipeIndex, out WINUSB_PIPE_INFORMATION PipeInformation);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_ReadPipe(SafeFileHandle InterfaceHandle, byte PipeID, byte[] Buffer, uint BufferLength, out uint LengthTransferred, IntPtr Overlapped);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_SetPipePolicy(IntPtr InterfaceHandle, byte PipeID, uint PolicyType, uint ValueLength, ref uint Value);

    [DllImport("winusb.dll", SetLastError = true)]
    public static extern bool WinUsb_WritePipe(SafeFileHandle InterfaceHandle, byte PipeID, byte[] Buffer, uint BufferLength, out uint LengthTransferred, IntPtr Overlapped);
    #endregion

    #region Public Methods
    public static string GetDescriptor(SafeFileHandle defaultInterfaceHandle, byte index, string errorMessage)
    {
        var buffer = new byte[256];
        var isSuccess = WinUsb_GetDescriptor(defaultInterfaceHandle, USB_STRING_DESCRIPTOR_TYPE, index, EnglishLanguageID, buffer, (uint)buffer.Length, out var transfered);
        WindowsDeviceBase.HandleError(isSuccess, errorMessage);
        var descriptor = new string(Encoding.Unicode.GetChars(buffer, 2, (int)transfered));
        return descriptor.Substring(0, descriptor.Length - 1);
    }
    #endregion
}

With any of these solutions you will either need to poll for the device on an interval, or use one of the API's native device listening classes. However, this library puts a layer across Hid, and USB on all platforms so that you can detect connections and disconnections easily: https://github.com/MelbourneDeveloper/Device.Net/wiki/Device-Listener . This is how you would use it:

internal class TrezorExample : IDisposable
{
    #region Fields
    //Define the types of devices to search for. This particular device can be connected to via USB, or Hid
    private readonly List _DeviceDefinitions = new List
    {
        new FilterDeviceDefinition{ DeviceType= DeviceType.Hid, VendorId= 0x534C, ProductId=0x0001, Label="Trezor One Firmware 1.6.x", UsagePage=65280 },
        new FilterDeviceDefinition{ DeviceType= DeviceType.Usb, VendorId= 0x534C, ProductId=0x0001, Label="Trezor One Firmware 1.6.x (Android Only)" },
        new FilterDeviceDefinition{ DeviceType= DeviceType.Usb, VendorId= 0x1209, ProductId=0x53C1, Label="Trezor One Firmware 1.7.x" },
        new FilterDeviceDefinition{ DeviceType= DeviceType.Usb, VendorId= 0x1209, ProductId=0x53C0, Label="Model T" }
    };
    #endregion

    #region Events
    public event EventHandler TrezorInitialized;
    public event EventHandler TrezorDisconnected;
    #endregion

    #region Public Properties
    public IDevice TrezorDevice { get; private set; }
    public DeviceListener DeviceListener { get; private set; }
    #endregion

    #region Event Handlers
    private void DevicePoller_DeviceInitialized(object sender, DeviceEventArgs e)
    {
        TrezorDevice = e.Device;
        TrezorInitialized?.Invoke(this, new EventArgs());
    }

    private void DevicePoller_DeviceDisconnected(object sender, DeviceEventArgs e)
    {
        TrezorDevice = null;
        TrezorDisconnected?.Invoke(this, new EventArgs());
    }
    #endregion

    #region Public Methods
    public void StartListening()
    {
        TrezorDevice?.Dispose();
        DeviceListener = new DeviceListener(_DeviceDefinitions, 3000);
        DeviceListener.DeviceDisconnected += DevicePoller_DeviceDisconnected;
        DeviceListener.DeviceInitialized += DevicePoller_DeviceInitialized;
    }

    public async Task InitializeTrezorAsync()
    {
        //Get the first available device and connect to it
        var devices = await DeviceManager.Current.GetDevices(_DeviceDefinitions);
        TrezorDevice = devices.FirstOrDefault();
        await TrezorDevice.InitializeAsync();
    }

    public async Task WriteAndReadFromDeviceAsync()
    {
        //Create a buffer with 3 bytes (initialize)
        var writeBuffer = new byte[64];
        writeBuffer[0] = 0x3f;
        writeBuffer[1] = 0x23;
        writeBuffer[2] = 0x23;

        //Write the data to the device
        return await TrezorDevice.WriteAndReadAsync(writeBuffer);
    }

    public void Dispose()
    {
        TrezorDevice?.Dispose();
    }
    #endregion
}