Re: [pyusb-users] re ctrl_transfer

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

2011/11/29 Eric Hewett <eri...@gm...>:
>                     print dev.ctrl_transfer(0x60, 0x09, msg, 0, len(msg))

This line makes no sense. Your bmRequestValue is invalid in USB 2.0 (I
haven't read the 3.0 spec yet). What are you trying to do? Send msg?
Please take a look at ctrl_transfer reference:

     |  ctrl_transfer(self, bmRequestType, bRequest, wValue=0,
wIndex=0, data_or_wLength=None, timeout=None)
     |      Do a control transfer on the endpoint 0.
     |
     |      This method is used to issue a control transfer over the
     |      endpoint 0(endpoint 0 is required to always be a control endpoint).
     |
     |      The parameters bmRequestType, bRequest, wValue and wIndex are the
     |      same of the USB Standard Control Request format.
     |
     |      Control requests may or may not have a data payload to write/read.
     |      In cases which it has, the direction bit of the bmRequestType
     |      field is used to infere the desired request direction. For
     |      host to device requests (OUT), data_or_wLength parameter is
     |      the data payload to send, and it must be a sequence type convertible
     |      to an array object. In this case, the return value is the
number of data
     |      payload written. For device to host requests (IN), data_or_wLength
     |      is the wLength parameter of the control request specifying the
     |      number of bytes to read in data payload. In this case, the return
     |      value is the data payload read, as an array object.



-- 
Best Regards,
Wander Lairson Costa
https://github.com/walac
https://gitorious.org/~walac