Re: [pyusb-users] Help with writing a driver for USB HID device.

[Wander L. C. <wan...@gm...>]

2014-11-13 12:14 GMT-02:00 Anatoly Verkhovsky <an...@gm...>:
> Hi,
>

Hi, sorry for the delay, but I was out most of the month.

> I'm writing a driver for a device.  It was originally using MDB ICP, but now
> it ships with a USB to MDB bridge, why they have chosen to do it as HID
> rather then USB Serial i have no idea.  So behind the usb there is a simple
> serial protocol.
>

[snip]

> Here is the gist of my code:
>
> dev = usb.core.find(idVendor=0x155d, idProduct=0x0002)
> # check and remove kernel driver
> dev.set_configuration()
> dev.reset()

iirc, reset is problematic in Windows (maybe a should log a warning
for this), what if you remove it?

> # bmRequestType, bRequest are taken from SnoopyPro trace.
> res = dev.ctrl_transfer(0x22, 0x9, 0, 0, [0x02, 0x85, 0x0a], 1000)

This seems to be a class request, so it is a HID class request?

> data = dev.read(0x82, 32, timeout=10000)
>
> ctrl_transfer fails with USBError(32, 'Pipe error') and
> after couple of retries : USBError(19, 'No such device (it may have been
> disconnected)')

In general, this kind of errors in Windows is due to the reset call.

> i have also tried the whole byte string from the capture
>
> res = dev.ctrl_transfer(0x22, 0x9, 0, 0, [0x03, 0x02, 0x85, 0x0a, 0x05,
> 0x14, 0xff, 0xff], 1000)
>
> to same effect.
>
> So what am i missing?
> Why is the trace saying that host to device message is using function 0x1b
> (Class interface) and device to host is using function 0x08 (control
> transfer), shouldn't it be the other way around?
>
> thanks,
> Anatoli
>
>
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-- 
Best Regards,
Wander Lairson Costa