I have one use-case where the current API is quite painful to work around, and I think adding support for write-only or read-only opening would help a lot of people.

My scenario:
I need to send Feature Reports to a HID mouse (mostly to control RGB lighting, DPI stages, polling rate, etc. on gaming mice).

On Windows:
The mouse is opened successfully with GENERIC_WRITE access
Writing Feature Reports (via HidD_SetFeature) works perfectly
But Windows refuses to open the same device with GENERIC_READ access.
When I do device.TryOpen(out var stream) in HidSharp, it requests both read and write access and fails.

Feature request / suggestion
An OpenMode / Access option in TryOpen(OpenConfiguration)

Something like:
var config = new OpenConfiguration();
config.SetOption(OpenOption.ReadAccess, true);
config.SetOption(OpenOption.WriteAccess, true);
device.TryOpen(config, out var stream);

This would allow clean write-only usage for exactly the kind of devices that Windows protects from being read (mice, some keyboards, touchpads, etc.) while still letting us send output/feature reports.

Thanks for considering this.

Thanks for this library. There's a problem in the report descriptor parsing with signed values for axis (PhysicalMinimum and LogicalMinimum).

When a negative value is found, it is forced to 0 in Reports/Encoding/EncodedItems, line 160 and 162 :

Changing the following two lines fixes the bug:

EncodedItem.cs : L160 change
{ DataValue = (uint)(sbyte)value; if (value < 0) { Data.Add(0); } }
to
{ DataValue = (uint)(sbyte)value; }

and EncodedItem:L162 change
{ DataValue = (uint)(short)value; if (value < 0) { Data.Add(0); Data.Add(0); } }
to
{ DataValue = (uint)(short)value; }

I don't understand what is the purpose of these 2 tests, and if it is a correct fix. Currently I'm stuck in the development of a plugin for a software that uses this library in a dll because of this bug.

Thanks for the great HidSharp library, I find it very useful. I am using it in one C# project to communicate with a specific device and want to be able to write unit tests for it. Unfortunately, the library currently makes use of concrete types with no interfaces. This makes it hard to mock/fake for testing.

Is there any chance an `IHidDevice` interface could be added to the NuGet package please? I would be happy to contribute it myself, if you are accepting outside contributions and can tell me how best to share my code with you, as it isn't hosted on GitHub.

I envisage something like this:

```
public interface IHidDevice
{
    Stream Open();
    int ProductID { get; }
    int VendorID { get; }
}
```

Thanks for your effort in developing this.

I am currently trying to implement a VNC client in a C# form using this. I tried VNCSharp previously but found the performance to be poor. RemoteViewing seems much better in that respect. However I find that if I use any sizemode other than AutoSize then the mouse scaling seems incorrect - i.e. I cannot reach the bottom X amount of the screen, depending on how much the size of the control differs from that used by autosize.

If I use Autosize the problem I have is that the control is then bigger than the form in which I need to display it. I added a panel and made this the parent of the control so I at least get scrollbars and everything works but not userfriendly! Anyideas on a better solution?

TIA

Mike

I have a USB scanner for bar codes/QR codes/MRZ.
I have a user manual from the manufacturer, which contains a set of QR codes that allow me to configure the device.
For example by scanning the following values:

$>:S01010F.<$ (Enter Setup)
$>: S0F0516.<$ (USB HID POS)
$>:S01000F.<$ (Exit Setup)

I was able to switch the device to "USB HID POS" mode. (default mode being "USB HID-KBW" in which the scanner behaves like a keyboard)
In this mode I am able to read scanned data using the HidSharp library.

However I also need to be able to change the settings of the device programmatically. But when I call stream.Write, I always get the following exception:

System.IO.IOException: 'Operation failed early: The parameter is incorrect'

Stack trace:
at HidSharp.Platform.Windows.NativeMethods.OverlappedOperation(IntPtr ioHandle, IntPtr eventHandle, Int32 eventTimeout, IntPtr closeEventHandle, Boolean overlapResult, NativeOverlapped* overlapped, UInt32& bytesTransferred)

There's an inner exception that just says Win32Exception: 'The parameter is incorrect' (no stack trace)

Info about the device:

// hdev.ToString() + " | " + hdev.DevicePath
Linux 3.10.14 with dwc2-gadget hidpos 00000000 (VID 4619, PID 33287, version 3.10) | \\?\hid#vid_120b&pid_8207#7&52366e0&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}

(the device itself has "Linux" in the name, I'm currently running Windows 10)

The following is an enumeration over the device's Reports:

Max Lengths: Input 64, Output 64, Feature 0
Serial Ports:
1 device items found.
Usage: 8C0001 9175041
Input: ReportID=2, Length=64, Items=1
63 Elements x 8 Bits, Units: None, Expected Usage Type: 0, Flags: Variable, BufferedBytes, Usages: 8C00FE 9175294
Output: ReportID=4, Length=64, Items=1
63 Elements x 8 Bits, Units: None, Expected Usage Type: 0, Flags: Variable, Relative, Nonlinear, Volatile, Usages: 8C0000 9175040

What I'm trying to do:

Assuming the device supports receiving setup commands, and that these are the same as the commands from the QR codes, I've been trying to send the following commands to the device (one at a time):

01010F (Enter Setup)
0C0814 (Set external illumination to "Always on")
01000F (Exit Setup)

NOTE: I've tried sending it in the format $>:S01010F.<$ and S01010F, but I suspect those are just some tags telling the QR parser it's a command, and the actual command is the 6 digit hex string.

I've tried creating the input buffer diretly:
var enterSetupBuffer = Encoding.ASCII.GetBytes("01010F");

I've tried creating a byte array of size 64 and setting the first few bytes in the array:
var someBuffer = new byte[64];
someBuffer[0] = 0x01;
someBuffer[1] = 0x01;
someBuffer[2] = 0x0F;
(and some variations on this)

no matter what I do, I get the same error: Operation failed early: The parameter is incorrect.
Some more details: I try to write using the HidStream.Write(buffer). I attempt the write before I start reading from the device. stream.CanWrite is returning true.

As you've probably guessed, I'm not good with hardware. I'm primarily a business application developer. All my attempts so far have been pretty much guesswork. I don't even know if it's the device rejecting my attempts at communication, or if there's something else I don't even know about tripping me up before the data is even sent to the device.

Any help would be greatly appreciated.

I have no troubles with 8-bit. Just with 16-bit joystick I'm having troubles with.

Here's the code:

static void Main()
{
    var list = DeviceList.Local;
    
    var joystick = list.GetHidDeviceOrNull(productID: 12345);

    if (joystick != null)
    {
        using (var stream = joystick.Open())
        {
            var inputReportBuffer = new byte[joystick.GetMaxInputReportLength()];
            while (true)
            {
                try
                {
                    int length = stream.Read(inputReportBuffer, 0, inputReportBuffer.Length);
                    Console.Write($"Worked!\n");
                    Thread.Sleep(1000);
                }
                catch (Exception ex)
                {
                    Console.Write($"Crashed!\n");
                    Console.WriteLine($"Exception: {ex.Message}\n{ex.StackTrace}");
                }

            }
        }
    }
    else
    {
        Console.WriteLine("Joystick not found.");
    }
}

Please help me. I really appreciate any kind of help.

I've noticed that after some random time the HidManager thread starts looping rapidly on Linux. The loop pins one core to 100% usage.
I've tried to profile the code a bit, and it seems that the NativeMethods.poll returns immediately (Platform/Linux/LinuxHidManager.cs, row 63, "ret = NativeMethods.retry(() => NativeMethods.poll(fds, (IntPtr)1, -1));").

My usage of the library is just opening a device, sending a report to the HID stream and reading a response report, then closing the stream. I'm doing this every 5 minutes or so, and at some random time the HidManager thread starts to eat up the CPU. The program seems to continue working despite this.

We have a custom HID device that has OutputReportByteLength set to 4 bytes in firmware, but when we open it in Windows, the value is equal to the InputReportByteLength, i.e. 31.

Is it Windows error ?
Linux reports correct value - HidSharp was not used there to test.

What I'm seeing is that I'm writing data to EP2 (64 Bytes, 10ms, INT) with a hidStream.Write() call, I can see on my USB analyzer (a Beagle USB 12) that the bytes are making it out to the device but on the device firmware side the endpoint status never reports an Event Pending (Out Buffer Full), which is how my firmware knows that data has been received on the endpoint.  Like I said, it seems more likely to be an issue on the device side, but wanted to at least see if there's any funny business I could check for on the host PC side.

Is anyone aware of any known issues with HIDSharp interfacing with 2.0 devices on 3.0 ports?  Any gotchas I should be aware of maybe?

Im working on a project, and have been having some success with HidSharp. I can read from my device just fine, and can access the data i need from the IN reports.

However I totally cannot see how i can write OUT reports back to the device. I've trawled the internet, but no examples.

Ive found I can get the OUT report I need using the GetReport() method but i dont know how to write my values into it, or send it.

Any advice/help much appreciated.

To be more specific.
* I can detect the portal just fine and get the device.
* I can open a HidStream
* I then try to send the "restart" message. Basically report Zero and the letter R, the rest all zeros.
* As soon as this is send out the portal starts sending status messages which I receive continuously. So the message did wake up something.
* However the write errors out with an exception. On my linux laptop its and I/O exception hardcoded in the output source code of hidsharp and on windows its a timeout exception.

I'm no usb export and have little clue why this happens.

I converted portalIO.cpp to the C# code below. I must be missing something silly I think. No reason for it to work using the original cpp code and not thru HidSharp. The first write failure occurs on the call to restartportal. After that I am buried in status output from the portal but nothing else. Any further write messages give the same result

If anyone has a clue or suggestion on what to try next? That would be appreciated.

using System;
using System.Text;
using HidSharp;
using System.Linq;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using HidSharp.Reports;
using HidSharp.Reports.Input;

namespace SkyReaderLib
{
    public class PortalIO
    {
        public const int rw_buffer_size = 0x21;
        public const int TIMEOUT = 30000;
        public const int SKYLANDER_SIZE = 1024;
        public const int MAX_STR = 255;
        private HidDevice portal;
        private HidStream portalStream;

        private bool initialized = false;

        public event EventHandler<StatusChangedEventArgs> StatusEvent;

        public static IEnumerable<HidDevice> ListPortals()
        {

            IEnumerable<HidDevice> devices = DeviceList.Local.GetHidDevices()
                .Where(x => (x.VendorID == 0x12ba || x.VendorID == 0x54c || x.VendorID == 0x1430)
                    && (x.ProductID == 0x150 || x.ProductID == 0x967));

#if DEBUG
            if (devices.Any())
            {
                Console.WriteLine("Found portal usb devices:");
                foreach (HidDevice device in devices)
                {
                    Console.WriteLine($"\t{device.GetFriendlyName()}");
                }

            }
#endif
            return devices;
        }

        // Send a command to the portal
        private void Write(byte[] message)
        {

            try
            {
                byte[] buffer = new byte[portal.GetMaxOutputReportLength()];
                message.CopyTo(buffer, 0);
#if DEBUG
                Console.WriteLine("Issued report out:");
                Console.WriteLine(string.Join(" ", buffer));
#endif
                portalStream.Write(buffer);
            }
            catch (Exception e)
            {
                Console.WriteLine($"Exception while issuing a report occured: {e}");
            }
       

        }

        private bool CheckResponse(out RWBlock response, byte expect)
        {
            response = new RWBlock();
#if DEBUG
            Console.WriteLine(">>> CheckResponse\n");
#endif

            int result = portalStream.Read(response.buffer, 0, rw_buffer_size);

            if (result < 0)
                throw new Exception("Could not read response");

#if DEBUG
            Console.WriteLine("CheckResponse read = {0} bytes\n", result);
#endif

            response.dwBytesTransferred = result;

            // found wireless USB but portal is not connected
            if (response.buffer[0] == 'Z')
                throw new Exception("Found portal dongle, but portal not connected");

            // Status says no skylander on portal
            // if (response->buffer[0] == 'Q' && response->buffer[1] == 0)
            //     throw 11;

#if DEBUG
            Console.WriteLine("<<< CheckResponse\n");
#endif
            return (response.buffer[0] != expect);

        }

        //
        public void PortalStatus()
        {
            byte[] buffer = new byte[portal.GetMaxOutputReportLength()];

            buffer[0] = 0;
            buffer[1] = (byte)'S';
           
            Write(buffer);
        }

        // Start portal
        public void RestartPortal()
        {
            byte[] buffer = new byte[portal.GetMaxOutputReportLength()];

            buffer[0] = 0;
            buffer[1] = (byte)'R';
            Write(buffer);
                       
        }

        // Antenna up / activate
        public void ActivatePortal(int active)
        {
            byte[] buffer = new byte[portal.GetMaxOutputReportLength()];
           
            buffer[0] = 0;
            buffer[1] = (byte)'A';
            buffer[2] = (byte)active;

            Write(buffer);
        }

        // Set the portal color
        public void SetPortalColor(byte r, byte g, byte b)
        {
            byte[] buffer = new byte[portal.GetMaxOutputReportLength()];

            buffer[0] = 0;
            buffer[1] = (byte)'C';
            buffer[2] = r; // R
            buffer[3] = g; // G
            buffer[4] = b; // B

            Write(buffer);
        }

        // Release hPortalInstance
        ~PortalIO()
        {
            ActivatePortal(0);
            portalStream.Close();
        }

        public void Flash()
        {

            for (; ; )
            {
                ActivatePortal(1);
                ActivatePortal(0);
            }
        }

        public PortalIO(HidDevice portal)
        {
            Console.WriteLine("Connecting to portal.\n");

            this.portal = portal;

            initialized = OpenPortal(portal);
            if (initialized)
            {
                RestartPortal();
                ActivatePortal(1);
                SetPortalColor(0xC8, 0xC8, 0xC8);
            }
            else
            {
                Console.WriteLine("Error initializing portal.");
            }
        }

        private bool OpenPortal(HidDevice portal)
        {
            Console.WriteLine(portal.GetMaxInputReportLength());
            ReportDescriptor descriptor = portal.GetReportDescriptor();

            HidDeviceInputReceiver reciever = descriptor.CreateHidDeviceInputReceiver();
            bool opened = portal.TryOpen(out portalStream);

            var x = portal.GetReportDescriptor();

            reciever.Start(portalStream);
            reciever.Received += OnReceiverReceived;
           
            portalStream.Closed += PortalStreamOnClosed;
           
            return opened;
        }

        private void PortalStreamOnClosed(object? sender, EventArgs e)
        {
            Console.WriteLine("Closed!");
        }

        private void OnReceiverReceived(object sender, EventArgs args)
        {
            try
            {
                var receiver = (HidDeviceInputReceiver)sender;

                if (receiver.Stream?.Device == null)
                {
                    return;
                }

                var length = receiver.Stream.Device.GetMaxInputReportLength();

                var buffer = new byte[length];

                if (receiver.TryRead(buffer, 0, out Report report))
                {
                   // Console.WriteLine($"Received report with id: {report.ReportID}, type: {report.ReportType}");

                    report.Read(buffer, 0, (bytes, offset, item, dataItem) =>
                    {
                       // Console.WriteLine(string.Join(" ", bytes));
                    });

                    switch((char)buffer[1])
                    {
                        case 'S':
                            StatusEvent?.Invoke(this, new StatusChangedEventArgs(buffer));
                            break;
                        default:
                            break;
                    }
                }
                else
                {
                    Console.WriteLine("Failed to read report.");
                }
            }
            catch (Exception e)
            {
                Console.WriteLine($"Exception while reading report occured: {e}");
            }
        }

    }
}

When I build into a mac application, if I call application.Quit() to exit application, it freeze to, and also can be recovered by change device list(plug some device in/out).

If not call GetDeviceList(), all about above will not happend.Also, DeviceListChanged callback will not be called.

I wanna know how to repair this issue.

Please help me to solve this issue.

private static object lo = new object();
        public byte[] WriteAndWaitResponse(byte[] data)
        {

            lock (lo)
            {
                byte[] result;
                Console.WriteLine("vid:" + vendorId + " pid:" + productId);

                if (!DeviceList.Local.TryGetHidDevice(out Dev, vendorId, productId))
                {
                    Console.WriteLine("Cannot GetHidDevice");
                    return null;
                }

                HidStream stream = null;
                if (Dev.CanOpen)
                {
                    
                    try
                    {
                        OpenConfiguration configuration = new OpenConfiguration();
                        stream = Dev.Open();
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                    }
                    if(stream == null)
                    {
                        Console.WriteLine("Try Open failed");
                    }
                }
                else
                {
                    Console.WriteLine("Cannot Open");
                }

                try
                {
                    stream.Write(data);
                    Console.WriteLine("data:" + data.Length);
                    Thread.Sleep(100);
                    result = stream.Read();
                    Console.WriteLine("result:" + result.Length);

                    return result;
                }
                catch (Exception ex)
                {

                    throw new RealDeviceException("error while writing to USB", ex);
                }
            }
        }