USB interaction from user space. I need some light please!

[sinosoidal]

Hi, I'm developing a driver for a usb device. I have already a driver sample that allows me to get data from my device. And the sample code to interact with the device is a console application. I need to get that data into a C# program and now I don't know what to do. I can think in some options like: - Do this directly in the driver layer (which is a big puzzle) - Wrap the code of the sample app in a C++ dll which I can then use in the C# side (don't know which kind of project that belongs to) So, I was looking for some lights in order to see where I should focus my development efforts. Any help would be appreciatted. With my best regards, Nuno

[Roger Stoltz]

I suggest you write a DLL that exposes the functionality of your device in the API. This is the most common way and you'll be able to use the DLL from whatever programming language.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

[Lost User]

Hi sinosoidal, The DeviceIoControl Function[^] can be called directly from your C# application. There is no need to create a C++ DLL when you can pass information to and from a device driver with the C# language. Take a look in your USB driver code and look for the IRP_MJ_DEVICE_CONTROL entry point. Should be something like:

DriverObject->MajorFunction[IRP_MJ_DEVICE_CONTROL] = SomeFunction

This defines the function which processes IOCTL codes. All you need to do is define a new IOCTL code. You simply pass a pointer in the DeviceIoControl lpOutBuffer parameter and the device driver can write data into the buffer at this address. Its extremely simple. I would recommend spending a few hours playing with the sample project at: WinDDK\6001.18002\src\general\ioctl\ This will give you an idea about how simple communication with a device driver is. If the data arriving on the USB device needs to fire an event to notify your usermode application you can view the sample located at: WinDDK\6001.18002\src\general\event I highly recommend investing a few hours experimenting with these samples. The C# language is full featured and there is no reason to write a native DLL if the parent application is managed. You can communicate with the device driver directly from your C# application. Best Wishes, -David Delaune

[sinosoidal]

Hi, Thanks for the replies. That was good news for me. I'm trying to explorer the direct connection to the USB device from C# using DeviceIOControl. I found an example with code from an article here in codeproject. The example, basicly interacts with an pci card, but i have seen another example of interaction, but this time with an usb device and they both start with CreateFile passing the device GUID. However, i cant have a valid handle. I think i'm passing the right guid of the device, because i'm getting it from the driver it self.

hFileHandle = INVALID_HANDLE_VALUE;
//open handle
hFileHandle = CreateFile("{00873fdf-61a8-11d1-aa5e-00c04fb1728b}",
GENERIC_READ |
GENERIC_WRITE,
0,
(IntPtr)0,
OPEN_EXISTING,
0,
NULL);

            if (hFileHandle == INVALID\_HANDLE\_VALUE)
            {
                Console.WriteLine("Cannot open driver handle");
                return;
            }

Any tips? Thanks, Nuno

[Lost User]

Hi Nuno, You can use the GetLastError Function[^] or the managed equivilent Marshal.GetLastWin32Error()[^] to see why CreateFile is failing. You must add this call immediately following CreateFile. What type of USB device are you interacting with? Typically the SetupDiGetDeviceInterfaceDetail Function[^] is used to obtain the CreateFile() compatible device path. Best Wishes, -David Delaune

[sinosoidal]

Hi David, I made it! However it was a little hard to get the device name. But I made it! :) I have to try your suggestion to get the device name more genericly. In what regards to read from the device, I'm using readfile function which was what the test app was calling, because, otherwise, I didn't knew which IO_CTL codes to use in order to invoke the request! :) I'm still ambienting myself to the windows programming model. Your help crucial guys. Thank you very much, With my best regards, Nuno PS: you'll see me again here for sure! :D