Windows USB example

[gavagai]

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.

[high_flyer]

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

[wysota]

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.

[high_flyer]

I haven't looked at the code.

[squidge]

When you say:

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();

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();

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Have you tried:

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

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

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

[gavagai]

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

[pavanbarot]

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.

[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

[pavanbarot]

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

[gavagai]

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.

[purnima]

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

[caodungviet]

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

[squidge]

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

[kuzulis]

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

[squidge]

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.

[kuzulis]

aah, I understand, thank you.

[caodungviet]

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

[squidge]

Please rephrase. Don't understand.

[caodungviet]

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!!

[wysota]

You mean it reboots?