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Thanks!
On Sep 8, 2011, at 6:45 AM, JamesPK wrote:
Hi,
Apologies for what might be a basic libhid question.
I'm running Ubuntu, and using libhid via Python to communicate with
a HID device (and have used 'lsusb' to glean all the details of the
device).
I've started out with the example code here: http://anonscm.debian.org/viewvc/libhid/trunk/swig/test_libhid.py
.I added the vendor and product ID and the example code itself
worked FINE.
I then added some code to the example. From the 'snooping' on the
communication with the device under Windows it needs a control
message with an initialisation string to initialise the device,
which I thought would be:
Not to sound too nit-picky, but is it an actual USB control transfer,
or is it just a message that is being sent to the device?
USB has the notion of Control endpoints (EP0 IN and OUT), and also
Interrupt endpoints. Not all devices have interrupt endpoints, but if
you post the output of 'lsusb -v' (run as root, preferably after
something like libhid has detached the kernel HID driver), we can see
which endpoints are available.
INIT_SEQ='0x20 0x00 0x08 0x01 0x00 0x00 0x00 0x00'
ret = hid_interrupt_write(hid, 0, INIT_SEQ, 8)
if ret != HID_RET_SUCCESS:
log_error("hid_set_output_report", ret)
But when I added the above spinet to the example and run it I get:
(ALL messages fine up to here)
---------------------
NOTICE: hid_force_open(): successfully opened USB device 006/002[0].
TRACE: hid_reset_parser(): resetting the HID parser for USB device
006/002[0]...
TRACE: hid_dump_tree(): iterating the parse tree for USB device
006/002[0]...
TRACE: hid_reset_parser(): resetting the HID parser for USB device
006/002[0]...
TRACE: hid_interrupt_write(): writing interrupt report to device
006/002[0] ...
WARNING: hid_interrupt_write(): failed to perform interrupt write to
device 006/002[0]: error submitting URB: No such file or directory
---------------------
Ah, I think I see what's going on: you passed endpoint 0 to
hid_interrupt_write() - it should be 1 or higher. Again, lsusb output
will pin this down.
Any ideas/pointers would be much appreciated.
Thanks
James
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