Re: [Libusb-devel] Control transfers

[Nuno S. <ns...@ed...>]

Hi again,

I'm claiming interface before setting mode:

This is my device side control packets handling (LUFA syntax):

case 0x12:
            if (bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_VENDOR | 
REQREC_DEVICE))
            {
                Endpoint_ClearSetupReceived();

                PORTD ^=0xff;
               
                /* Send the flag to the host */
                Endpoint_ClearSetupOUT();
            }
           
            break;

And my libusb transfer request:

uint8_t data = 0x00;
int r;
r = libusb_control_transfer(handle, 0x40, 0x12, 0, 0, &data, 1, 1000);

0x12 is my request... i choose 0x12 as I could choose 0x00 as I'm trying 
to set up vendor request, right?

then I'm looking for a request type from host to device, from vendor 
type, which target is the device itself

REQDIR_HOSTTODEVICE -> 0 at bit 7
REQTYPE_VENDOR -> 2 at bit 5 means 10 starting at bit 5
REQREC_DEVICE -> 00000 starting at bit 0

Results in 0100 0000 which is 0x40!

I have a -9 error an endpoint error

Still haven't found the problem...

Thx,

Nuno

Tim Roberts wrote:
> Nuno Santos wrote:
>   
>> Today I was doing some experiments on control transfers with libusb. I  
>> was setting a custom request to process on the device side,
>> and then invoking a control transfer on the host side to activate that  
>> request.
>>
>> I was getting pipe error on the transaction.
>>
>> My device is only composed by a unique custom endpoint but I was  
>> assuming the use of the default control endpoint.
>>
>> Why could this not be working? What can possibly be the most direct  
>> cause?
>>   
>>     
>
> What exactly was the request you were trying?  One of the bit fields in
> the request code (in bmRequestType) says whether the request is aimed at
> the device, the interface, the endpoint, or "other".  If you pick
> "interface" or "endpoint", then you must have claimed the interface
> number that is specified in the request.  This trips up some people,
> because the Windows kernel does not enforce this.  The Linux kernel does.
>
> However, I think that reports an EACCESS error, so I could be blowing
> smoke.  How large was the transfer?  Control transfers are quite limited
> in size.
>
>