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POLibUsbDotNet UsbDevice.ControlTransfer hangs
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copied!<p>I have a C# .Net Winforms application, which uses LibUsbDotNet to program firmware into an USB-device (Atmel AVR32) using "DFU_DNLOAD" transfers, which is a special kind of control-transfers. This all works, BUT: A specific kind of transfer, which causes the device to erase its internal flash, fails to send an ACK within the correct timing.</p> <p>When this happens, my LibUsbDotNet connection becomes irreparably broken, which causes everything to fail.</p> <p>My code does the following:</p> <pre><code>int TransferToDevice(byte request, short value, byte[] data) { var setup = new UsbSetupPacket( (byte)(UsbCtrlFlags.Direction_Out | UsbCtrlFlags.RequestType_Class | UsbCtrlFlags.Recipient_Interface), request, value, 0, (short)data.Length); int n; IntPtr unmanagedPointer = System.Runtime.InteropServices.Marshal.AllocHGlobal(data.Length); System.Runtime.InteropServices.Marshal.Copy(data, 0, unmanagedPointer, data.Length); // UsbDevice obtained else-where if (!UsbDevice.ControlTransfer(ref setup, unmanagedPointer, data.Length, out n)) { n = 0; } System.Runtime.InteropServices.Marshal.FreeHGlobal(unmanagedPointer); return n; } // In order to do a "DFU_DNLOAD", the method above is used as follows: TransferToDevice(DFU_DNLOAD, Transactions++, data); // "data" is the payload // where DFU_DNLOAD is: private const byte DFU_DNLOAD = 1; // Transactions is short Transaction = 0; </code></pre> <p>The above code works (the device correctly receives the "DFU_DNLOAD" message), but the missing ACK is the problem. Once the error occurs, every attempt to communicate with the device (even if I try to re-initialize everything) fails, untill the device is disconnected and re-inserted...</p> <p>I would like to be able to reset or re-initialize the USB-connection somehow, when this error occurs. Currently I am only able to re-establish communications with the device by exiting my application and re-starting it manually.</p>

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