[pyusb-users] Specifying bRequest, wValue, wLength and wIndex in non-control requests

[Joel S. <jo...@sn...>]

Hi,

I'm trying to reverse engineering something with a windows driver, but I'm
having trouble replicating one of the reads it makes with pyUSB.

The driver sends a read-request on each endpoint, with different wValue,
wIndex and wLength fields set. I can see how to do this on the control
channel with pyUSB (using dev.ctrl_transfer), but I can't see how to set
these if I'm doing a read request as that just takes a length...

The driver packet looks like this in wireshark:

...
Endpoint: 0x80, Direction: IN
<snip>
URB:
bmRequestType: 0xc0
bRequest: 4
wValue: 0x0040
wIndex: 0 (0x0000)
wLength: 8

I'm not sure if I'm missing something about how USB works, or how pyUSB
works....any pointers much appreciated!

Thanks,

Joel