C++ dll for USB download in C# application

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  12 years ago

  by sumahs

  Suma H S

  Bangalore, India

  Joined 12 years ago
  Hi all, I am using a C++ dll (with functions to initialize, deinitialize, read and write data to USB port) in my C# application(with UI which allows user to select files to write to USB port). The objective of the application is to allow user select a file to download from PC to the target device and receive acknowledgements for every 256 bytes of data received. Once the entire file is downloaded a final acknowledgement is received. For USB communication, C++ API's are used. The problem that I am facing is that the application behaves unpredictably and fails to receive final acknowledgement sometimes. A single test application with USB API's (not converted to dll) in C++ (without UI) works fine, which means the target code and the API's are working fine. Code snippets here... public class UsbDownload { #region Imported DLL functions from usb.dll [DllImport("usb.dll")] private static extern HANDLE usbInit(); [DllImport("usb.dll")] private static extern BOOL usbDeinit(HANDLE hObject); [DllImport("usb.dll")] unsafe private static extern BOOL usbWrite(HANDLE hObject, void* buffer,DWORD nNumberOfBytesToWrite, ref System.UInt32 nNumberOfBytesWritten); [DllImport("usb.dll")] unsafe private static extern BOOL usbRead(HANDLE hObject, void* buffer,DWORD nNumberOfBytesToRead, ref System.UInt32 nNumberOfBytesRead); #endregion private bool writeFile(long nFileSize, byte[] filebuffer) { int nSize = 1; byte readData = 0; while (nSize <= nFileSize) { writeByte(filebuffer[nSize - 1]); if (nSize % TARGET_BUFFER_SIZE == 0) { #if (NO_ACK) Thread.Sleep(3); #else readByte(ref readData); if(readData != ACK_BYTE) { return false; } #endif } nSize++; } readData = 0; readByte(ref readData); if (readData != ACK_BYTE) { return false; } return true; } unsafe private bool writeByte(byte wrData) { byte[] data = new byte[1]; UInt32 noOfBytesWritten = 0; bool result = false; data[0] = wrData; fixed (byte* writePtr = data) { result = usbWrite(m_handle, writePtr, 1, ref noOfBytesWritten); } return result; } unsafe private bool readByte(ref byte rdData) { byte[] data = new byte[1]; UInt32 noOfBytesRead = 0; bool result = false; fixed (byte* readPtr = data) { result = usbRead(m_handle, readPtr, 1, ref noOfBytesRead); rdData = data[0]; } return result; } } } Another C# class creates the GUI, which I think, is unnecessary to put in here. Any suggestions as to what I might be doing wrong in the C# application, would be greatly appreciated. Thanks, Suma H S
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