Re: [Libusb-devel] libusb_interrupt_transfer timeout problem

[al <al...@al...>]

> From: Tim Roberts <ti...@pr...>
> 
> Al wrote:
>> I`ve been trying to do an interrupt read from my usb device, so far I`ve 
>> had no success.
>>
>> Any help on what I might be doing wrong would be most appreciated.
>>   
> 
> This is a HID device.  To save yourself a lot of grief, you should use
> libhid to talk to it.  libhid knows how to handle the interrupt
> endpoints and provides a better level of abstraction for this class of
> device.

Tried that, same problem I`m afraid.


>> Here`s the code snippet.
>>
>> devh = libusb_open_device_with_vid_pid(ctx,vendor, product);
>> ret = libusb_kernel_driver_active(devh, 0);
>> if (ret == 1) {
>> 	printf("interface 0 already claimed by driver \"%s\", attempting to 
>> detach it\n", buf);
>> 	ret = libusb_detach_kernel_driver(devh, 0);
>> 	printf("usb_detach_kernel_driver_np returned %d\n", ret);
>>      }
>> ret = libusb_claim_interface(devh, 0);
>> if (ret != 0) {
>> 	printf("claim failed with error %d\n", ret);
>> 	exit(1);
>> }
>>
>>
>> // send message to device, causes device to output configuration on 
>> endpoint 1
>> memcpy(buf, "\x59\xdd\x00\x00", 0x0000004);
>> ret = libusb_control_transfer(devh, LIBUSB_REQUEST_TYPE_CLASS + 
>> LIBUSB_RECIPIENT_INTERFACE, 0x0000009, 0x0000200, 0x0000000, buf, 
>> 0x0000004, 1000);
>>   
> 
> That's a SET_REPORT request for an output report (type 2), which means
> it is an output request.  In order to trigger a report to be read, you
> would usually sent a GET_REPORT (bRequest = 1, not 9).  Did you pull
> this from a trace?

Yep from trace, so I could have misread it.


>> // grab first 4 bytes of output
>> int transferred;
>> ret = libusb_interrupt_transfer(devh, LIBUSB_ENDPOINT_IN|0x1, buf, 
>> 0x0000004, &transferred,1000);
>>
>> it fails here with error -7
>>   
> 
> But did you get any data?  What was in "transferred"?

Nope 0 transferred, buffer is zero`d.

I`ll try changing the bRequest.

ta