On Fri, 11 Mar 2011 19:37:36 wander.lairson wrote:
> 2011/3/10 Andrew Errington <a.erring...@lancaster.ac.uk>:
>
> [snip]
>
> > How do I do this in pyUSB? So far I have managed to identify the device,
> > detach the driver (for interface 3, the HID interface) and I can read the
> > state of the GPIO pins (but I cannot write to them).
> >
> > Hints and tips would be welcome.
>
> What endpoint this data is sent to?
I'm not sure. SnoopUSB tells me there is no endpoint involved (it is n/a),
and you can see in the XML I sent it is -1, so I don't know. I am sure it is
supposed to be endpoint 0x83 on interface 3.
Here is the summary of the first packet from SnoopUSB. This is the first
packet that is sent when I set the GPIO from the test software:
Seq Dir Endpt Time Function Data Result
9 out down n/a 31.341 CLASS_INTERFACE 00 01 01 00
If I expand this packet in the SnoopUSB program I see this:
URB Header (length: 80)
SequenceNumber: 9
Function: 001b (CLASS_INTERFACE)
PipeHandle: 00000000
SetupPacket:
0000: 22 09 00 02 03 00 00 00
bmRequestType: 22
DIR: Host-To-Device
TYPE: Class
RECIPIENT: Endpoint
bRequest: 09
TransferBuffer: 0x00000004 (4) length
0000: 00 01 01 00
There is no more information to be seen in this packet. There are four
packets in the transaction. I assume that the following three packets are
acknowledgement and housekeeping (they are in the XML I sent, but they
are 'prettier' in SnoopUSB).
Here are the interfaces and endpoints. First, a short program to print them:
dev = usb.core.find(idVendor=0x0c76, idProduct=0x160b)
for cfg in dev:
sys.stdout.write(str(cfg.bConfigurationValue) + '\n')
for intf in cfg:
sys.stdout.write('\ti/f no:' + \
str(intf.bInterfaceNumber) + \
',' + \
str(intf.bAlternateSetting) + \
'\n')
for ep in intf:
sys.stdout.write('\t\te/p addr:' + \
str(hex(ep.bEndpointAddress)) + \
'\n')
Here is the output:
1
i/f no:0,0
i/f no:1,0
i/f no:1,1
e/p addr:0x1
i/f no:2,0
i/f no:2,1
e/p addr:0x82
i/f no:3,0
e/p addr:0x83
What should I look for/try next?
Thanks,
Andrew
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