Re: [Libusb-devel] Control transfers

[Alan S. <st...@ro...>]

On Tue, 7 Jul 2009, Nuno Santos wrote:

> Well,
> 
> What i'm doing is:
> 
> r = libusb_control_transfer(handle, 0x40, 0x12, 0, 0, &data, 1, 1000);
> 
> Where 0x40 means that I want to send a packet from the host to the 
> device (OUT), bit 7 =0, and that the requst is a vendor specific (10), 
> and that it is directed to the device (00000).
> 
> My request number is 0x12 which was what I defined in the event handler 
> in the device firmware.

May you didn't define it correctly.

> The result is a -9 error which is  a LIBUSB_ERROR_PIPE 
> <http://libusb.sourceforge.net/api-1.0/group__misc.html#ggb2323aa0f04bc22038e7e1740b2f29ef1406e98370900156484f5fe609270837>

That means the device returned a STALL.  You can verify this by using 
usbmon.

> But now, i don't know for sure if the request should be directed to the 
> device, or to a determined endpoint or interface! :)

It depends on what the request is supposed to do.  As the device 
implementor, that decision is up to you.

Alan Stern