Windows USB example

This program is an example of how to use an USB device in Qt.
It is limited only to the HID devices class (joystick, mouse, keyboard...)
It uses the standard Microsoft HID driver. If you use another driver you must know how it works.
It demonstrates how to:
-recognize a device by VID&PID
-read/write
-attach/detach notification
Two examples are provided:
-first example reads the XY position of a joystick
-second example sends a message to the device and waits for the answer.

See comments in source for details.

Licence: GPL.

I hope that this program can be useful to someone.

Excellent!
It might be a good idea if you'd add it to the examples section in the wiki, here it gets lost among the many other threads...
http://www.qtcentre.org/wiki/index.p...egory:Examples

I don't like the idea of using global variables. And threads access those variables without a proper protection. This is bound to blow up sooner or later.

I haven't looked at the code.

When you say:

Code:

---

QString s;
                    //to find a better way for this...
                    while(lpdbv->dbcc_name[i] != 0)
                    {
                        s.append(lpdbv->dbcc_name[i]);
                        i++;
                    }
                    s = s.toUpper();

---

Have you tried:

Code:

---

QString s = QString::fromWCharArray(lpdbv->dbcc_name).toUpper();

---

Don't know if it'll work, it's just something that sprung into mind when I read your code/comment.

hi squidge,
thanks for your suggestion. Yes, it works!
I had not seen this static function to convert wchar_t in QString.
Thanks again.

Thanks for Share awesome Example for USB Communication...
but i have problem to devide...... The "Device Class GUID" is {6bdd1fc6-810f-11d0-bec7-08002be2092f}
can u please explain me more.

i'll try this type #define HID_CLASSGUID {0x6bdd1fc6, 0x810f, 0x11d0,{ 0x08, 0x00, 0x2b, 0xe2, 0x09, 0x2f }}
but result is same not connected ....

please help me, i m waiting for u r kindly reply...
thanks in advance.

Don't use the class GUID returned by device manager, it don't works. It is the device SETUP GUID class. We need the device INTERFACE GUID class (see http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx).
Try this:
- be sure that your device is installed and recognized in the system
- start regedit and search for your vid&pid (VID_XXXX&PID_XXXX) in the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\DeviceClasses. You can get more of a result.
- Try to use the parent class GUID where the descriptor starts with the type of device (##?#HID#VID... or ##?#IMAGE#VID...).
For more informations see the examples in http://msdn.microsoft.com/en-us/library/ff551069.aspx

Your device seems to be an image device. I do not know if endpoint size (InputBuffer and OutputBuffer size) is correct for this device. Depends on the driver.

Good luck

Thanks a lot it's works fine....

ok, it works but I think it is not exactly correct.
Your image shows a generic class GUID for all USB devices (##?# USB VID # ...).
Better to use a GUID for a specific class of devices.
Search again to find something like # #? # IMAGE # VID_XXXX&PID_XXXX and uses its GUID.
Maybe I'm wrong, but I think for read / write operations you must use a more specific GUID.

I am new member to this forum. So this information is useful for me. I will try this.

sorry but i don't understand about The "Device Class GUID", please you help me?? for example,
#define HID_CLASSGUID {0x6bdd1fc6, 0x810f, 0x11d0,{ 0x08, 0x00, 0x2b, 0xe2, 0x09, 0x2f }}
so :{ 0x08, 0x00, 0x2b, 0xe2, 0x09, 0x2f }.what is it??
please explain for me,i don't understand about it. what it means?? sorry ,because my english is not good

They are device class GUIDs used in device detection and classification. See the Windows DDK for more information and other GUIDs.

Hi all.
And why different descriptors for reading and writing device?
(You can also open once a one descriptor for reading and writing!)

Quote:

---

Originally Posted by kuzulis

Hi all.
And why different descriptors for reading and writing device?
(You can also open once a one descriptor for reading and writing!)

---

You can but that will not work across all devices. Some devices for example are read-only, so if you try to open them as read/write the call will fail, but if you have seperate read and write only the write will fail, so you know the device is read-only and don't need to do additional work (such as reopening as read only and setting a read-only flag). Typically however you will know this before writing code but as an example it is impossible to know this in advance.

aah, I understand, thank you.

i can conect with USB, but when i open it ,so my computer is broke dow,, why such that??

Please rephrase. Don't understand.

sorry, because my english is not good..i can connect this project with USB,but when i open this project ,my computer can't run.
please help me!!

You mean it reboots?

sorry but i can't understand how you can search HID_CLASSGUID {0x6bdd1fc6, 0x810f, 0x11d0,{ 0x08, 0x00, 0x2b, 0xe2, 0x09, 0x2f }},.everytime i have searched and i allway search "{a5dcbf10-6530-11d2-901f-00c04fb951ed}" with the another USB.
please help me!! thanks
Please give me the directions by images!!

I don't understand your question. This example is made for HID devices, a5dcbf10-6530-11d2-901f-00c04fb951ed is USB raw device ?

sorry, i wrong. However how can you find PID and VID of a USB HID?? please help me!!

Use SetupDi API

Hi there

I'm a newbie in c++ programming, I'm doing my thesis and stealing code from here and there.... So thanks for the example first!

I noted that the ReadThread is actually eating one CPU because it's in an endless loop, checking for events. I added a sleep statement that lets it run once per second and CPU usage dropped dramatically. Of course you lose responsiveness and you get a notification a second after the device is plugged in, but I don't think it's a major drawback.

EDIT: My bad, I'm looking from the perspective of my device (a thermometer) that really doesn't run in realtime. Following joystick movement requires more frequent updates. Still some delay of 0.01sec won't be noticeable and should reduce CPU usage too.

Hi, all!
First of all I want to tell "Thanks" for this example!
Now I write project for using Magnetic Stripe Reader that recognized by Windows as USB HID Device:

Code:

---

##?#HID#VID_1136&PID_3003#6&2b575f1c&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}

---

But in this example it always return INVALID_HANDLE_VALUE in usbexample.cpp:273 on:

Code:

---

ReadHandle = CreateFile((DetailedInterfaceDataStructure->DevicePath), GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, 0);

---

And DevicePath is correct:

Code:

---

qDebug() << QString::fromWCharArray(DetailedInterfaceDataStructure->DevicePath);

---

return

Code:

---

\\?\hid#vid_1136&pid_3003#6&2b575f1c&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}

---

What's wrong?

Hi stringer,

try following code might it help's you.

Code:

---

HANDLE hFile = CreateFile( DetailedInterfaceDataStructure->DevicePath, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,  OPEN_EXISTING, 0,  NULL );

---

Thanks for quick reply!
But nope!

---

Added after 32 minutes:

When I call GetLastError() after CreateFile, I get number 5. Google tell me that this is ERROR_ACCESS_DENIED. Why?
My System is Windows 7 x64 with disabled UAC.

Assignment of WriteHandle goes well, but ReadHandle generate error ERROR_ACCESS_DENIED.
Maybe, for my task, use RAW Input Devices like here: http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx ?
But I don't know how. Can anybody help me?

Hooray! I get the example to WORK!
I just needed to switch MSR (Magnetic Stripe Reader) Mode from "Keyboard Emulation Mode" to "HID Mode" via 3rd Party Utility which absent in box for MSR.

i am trying to develop qt application using USB to control relay board..... I was trying this windows USB Example...
always getting an error message " :: error: No rule to make target `../../qt/2010.05/qt/mkspecs/win32-g++/qmake.conf', needed by `makefile'. Stop." Can anyone please give suggestion how to recover from this error.........Is there any sample application available using USB in windows.....

please reply to my post......can any one help me to overcome this problem.....

Call qmake. This has nothing to do with USB.

Please help me regarding this !!!!!!!!!!!!!... i have entered correct VID & PID for the device but this application is not showing the device connected......
i tried to connect USB relay board which uses Microchip Pic 18 series.... I want to control those relays through USB......

Are you sure your device is compliant with this example?

My device is getting connected with this app....... now the proble is that, wen am creating file ReadHandle and WriteHandle bot are getting value 0xffffffff...... i tried by changing the values but no use..... when i tried to display device path its showing correct only...... CreateFile function always returns 0xffffffff only..............

Hello, I am using this example and it seems to be recognizing my HID device just fine in the checkUSB(),
but, in the winEvent I am getting wParam = 7 all the time, both when I connect or disconnect the device, so it doesn't catch these events:
DBT_DEVICEARRIVAL = 0x8000 and DBT_DEVICEREMOVECOMPLETE = 0x8004.

any ideas?
Thanks

Quote:

---

My device is getting connected with this app....... now the proble is that, wen am creating file ReadHandle and WriteHandle bot are getting value 0xffffffff...... i tried by changing the values but no use..... when i tried to display device path its showing correct only...... CreateFile function always returns 0xffffffff only..............

---

Try to use this libraries and demos: microchip.com

---

Added after 6 minutes:

Quote:

---

Originally Posted by galrub

Hello, I am using this example and it seems to be recognizing my HID device just fine in the checkUSB(),
but, in the winEvent I am getting wParam = 7 all the time, both when I connect or disconnect the device, so it doesn't catch these events:
DBT_DEVICEARRIVAL = 0x8000 and DBT_DEVICEREMOVECOMPLETE = 0x8004.

any ideas?
Thanks

---

Try to add this line into .pro file:

Code:

---

DEFINES += _WIN32_WINNT=0x0501

---

Quote:

---

Originally Posted by stringer

Try to use this libraries and demos: microchip.com

---

Added after 6 minutes:

Try to add this line into .pro file:

Code:

---

DEFINES += _WIN32_WINNT=0x0501

---

---

well, it's just a part of the issue, I just realized that the USB hub for the front panel of this PC is, well, not a very 'well built' one,
so this is why I get the wParam = 7, I tried using the USB socket in the back... no problem there.
thanks.

Hi All,

I've followed this thread with great interest and with Gavagai's very usefull initial sourcefiles and everyone else's additions I finally managed to get a working usb interface between my PIC 4550 chip and a pc. I've attached my sources for both ends of the link so that others might find them useful. I also added some extra error trapping to make my life easier.

Note the PIC end is on a Mikroelectronica EasyPIC4 board using their C Pro software.

Hi All,
After I found this example I was very happy and even before trying I modified it to match with my application... then I found out that device detection worked properly but write failed.
I get a proper read and write handle, no errors at write, but... it seems to send nothing.

I went back to the example changed nothing but MY_DEVICE_VIDPID and added a debug message after WriteFile to check BytesWritten
It may be clear that the protocol to my device differs, but I should at least be able to send something even when it is wrong -- or not?
If I only received an error would help already :)

any ideas?
Thanks

---
BytesWritten always 0

Oops... inverted my error checking, WriteFile did give an error (87)

Hi there,
I have the same error..I am wondering if you managed to fix it!!
Thanks

Quote:

---

Originally Posted by gavagai

Don't use the class GUID returned by device manager, it don't works. It is the device SETUP GUID class. We need the device INTERFACE GUID class (see http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx).
Try this:
- be sure that your device is installed and recognized in the system
- start regedit and search for your vid&pid (VID_XXXX&PID_XXXX) in the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\DeviceClasses. You can get more of a result.
- Try to use the parent class GUID where the descriptor starts with the type of device (##?#HID#VID... or ##?#IMAGE#VID...).
For more informations see the examples in http://msdn.microsoft.com/en-us/library/ff551069.aspx

Your device seems to be an image device. I do not know if endpoint size (InputBuffer and OutputBuffer size) is correct for this device. Depends on the driver.

Good luck

---

Hi gavagai,
First of all thanks for the great upload.
I am tryint to build qt application to detect a usb device(Not necessarily a HID) when plugged in.
Now, i have two HIDs connected to my PC a keyboard and a mouse.
how do i know which VID/PID is for which device? Coz its really confusing even when i navigate to registry location you mentioned above.
how does HID differs from Mass storage device in terms of VID/PID?
Just want to put me in the right direction.
Thnx.

Hi Marc van der Kamp,

I am still getting error 87.. Have you fixed it ? I really need to make it work..
Please help me..

Many thanks

Quote:

---

Originally Posted by Marc van der Kamp

Oops... inverted my error checking, WriteFile did give an error (87)

---

Hi Marc van der Kamp,

I am still getting error 87.. Have you fixed it ? I really need to make it work..
Please help me..

Many thanks

Thanks for great example. With Qt 5 you should use code like:

To header:
bool nativeEvent(const QByteArray & eventType, void * message, long *result);

And to CPP:
bool USBexample::nativeEvent(const QByteArray & eventType, void * message, long *result)
{
MSG* msg = reinterpret_cast<MSG*>(message);
...
}

Hi
How i can get product name of HID device?
Thanks