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copied!<p>For anyone interested, here is the code that fixed the problem. This method is called when the firmware detects the SD card has either been inserted or deleted after power up. In essence, it unloads/loads the device driver:</p> <pre><code>[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)] public struct DEVMGR_DEVICE_INFORMATION { public uint dwSize; public IntPtr hDevice; public IntPtr hParentDevice; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 6)] public string szLegacyName; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)] public string szDeviceKey; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)] public string szDeviceName; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)] public string szBusName; } public enum DeviceSearchType : int { DeviceSearchByLegacyName = 0, DeviceSearchByDeviceName = 1, DeviceSearchByBusName = 2, DeviceSearchByGuid = 3, DeviceSearchByParent = 4 } class DevDriverInterface { [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)] public struct SECURITY_ATTRIBUTES { public int nLength; public IntPtr lpSecurityDescriptor; public bool bInheritHandle; } [DllImport("coredll.dll", SetLastError = true)] public extern static int ActivateDeviceEx(string device, IntPtr regEnts, UInt32 cRegEnts, IntPtr devKey); [DllImport("coredll.dll", SetLastError = true)] public extern static bool DeactivateDevice(int handle); [DllImport("coredll.dll", SetLastError = true)] public static extern int FindFirstDevice(DeviceSearchType searchType, IntPtr searchParam, ref DEVMGR_DEVICE_INFORMATION pdi); // Constructor public DevDriverInterface() { } public bool MountSDCardDrive() { const int INVALID_HANDLE_VALUE = -1; string mRegPath1 = ""; int handle = INVALID_HANDLE_VALUE; DeviceSearchType searchType = DeviceSearchType.DeviceSearchByDeviceName; DEVMGR_DEVICE_INFORMATION di = new DEVMGR_DEVICE_INFORMATION(); di.dwSize = (uint)Marshal.SizeOf(typeof(DEVMGR_DEVICE_INFORMATION)); String searchParamString = "SDH1"; IntPtr searchParam = Marshal.StringToBSTR(searchParamString); handle = FindFirstDevice(searchType, searchParam, ref di); if (handle == INVALID_HANDLE_VALUE) { // Failure - print error int hFindFirstDeviceError = Marshal.GetLastWin32Error(); using (StreamWriter bw = new StreamWriter(File.Open(App.chipDebugFile, FileMode.Append))) { String iua = "DevDriverInterface: error from FindFirstDevice: " + hFindFirstDeviceError.ToString(); bw.WriteLine(iua); } return false; } else { mRegPath1 = di.szDeviceKey; bool deactBool = DeactivateDevice((int) di.hDevice); if (deactBool == false) { using (StreamWriter bw = new StreamWriter(File.Open(App.chipDebugFile, FileMode.Append))) { String iua = "DevDriverInterface: DeactivateDevice: returned false - FAILED"; bw.WriteLine(iua); } return false; } Thread.Sleep(50); // Call ActiveDevice to setup the device driver handle = ActivateDeviceEx(mRegPath1, IntPtr.Zero, 0, IntPtr.Zero); if (handle == INVALID_HANDLE_VALUE) { // Failure - print error int hActivateDeviceError = Marshal.GetLastWin32Error(); using (StreamWriter bw = new StreamWriter(File.Open(App.chipDebugFile, FileMode.Append))) { String iua = "DevDriverInterface: error from ActivateDevice: " + hActivateDeviceError.ToString(); bw.WriteLine(iua); } return false; } } return true; } }; // end class </code></pre>

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