Usb

@inject Bit.Butil.Usb usb

var supported = await usb.IsSupported();

private UsbDevice? _device;

_device = await usb.RequestDevice();                       // every device the browser will show
_device = await usb.RequestDevice(new UsbDeviceFilter { VendorId = 0x2341 });

var granted = await usb.GetDevices();

@code {
    // The handle from RequestDevice above - a grant is per device, and this is the way back to one
    // the user has already chosen.
    private UsbDevice? _device;

    private async Task Session()
    {
        await _device!.Open();
        await _device.SelectConfiguration(1);

        // Nothing can be transferred until the interface is claimed, and the OS may already hold it
        // for a driver of its own.
        await _device.ClaimInterface(0);

        // ... transfers ...

        await _device.ReleaseInterface(0);
        await _device.Close();
    }
}

@code {
    private UsbDevice? _device;   // opened, with its interface claimed

    private async Task Transfer()
    {
        var read = await _device!.TransferIn(endpointNumber: 1, length: 64);
        var text = read?.Data is null ? "" : System.Text.Encoding.UTF8.GetString(read.Data);

        await _device.TransferOut(endpointNumber: 2, "ping"u8.ToArray());

        await _device.ControlTransferOut(new UsbControlTransferParameters
        {
            RequestType = "vendor",
            Recipient = "device",
            Request = 0x01,
            Value = 0x0001,
            Index = 0
        });
    }
}

await using var watch = await usb.SubscribeConnection(
    onConnected: device => Console.WriteLine($"+ {device.Info.ProductName}"),
    onDisconnected: device => Console.WriteLine($"- {device.Info.ProductName}"));

@code {
    private UsbDevice? _device;   // from RequestDevice

    // Drops the grant, so GetDevices stops returning it and the picker has to be shown again.
    private async Task Revoke()
    {
        var revoked = await _device!.Forget();
        _device = null;
    }
}