Great - thanks for the feedback. Comments online below:
On 09/09/11 03:22, Charles Lepple 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.
Good question - I'm not sure if its a control message required??? I
expect it might just be a normal 'write' message (as on double checking
the on the windows output the 'request' filed was set as listed as 'set
report' )
Ok - 'lsusb -v' is at base of post.
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.
Thanks.
James
-----------------------------------------------------------------
jamespk@hal:~/project/driver/hidapi$ sudo lsusb -v -d 0fde:ca01
Bus 006 Device 002: ID 0fde:ca01
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x0fde
idProduct 0xca01
bcdDevice 3.02
iManufacturer 0
iProduct 1 Universal Bridge
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 34
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Device
bInterfaceSubClass 0 No Subclass
bInterfaceProtocol 0 None
iInterface 0
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.10
bCountryCode 0 Not supported
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 34
Report Descriptor: (length is 34)
Item(Global): Usage Page, data= [ 0x00 0xff ] 65280
(null)
Item(Local ): Usage, data= [ 0x01 ] 1
(null)
Item(Main ): Collection, data= [ 0x01 ] 1
Application
Item(Local ): Usage, data= [ 0x01 ] 1
(null)
Item(Global): Logical Minimum, data= [ 0x00 ] 0
Item(Global): Logical Maximum, data= [ 0xff 0x00 ] 255
Item(Global): Report Size, data= [ 0x08 ] 8
Item(Global): Report Count, data= [ 0x08 ] 8
Item(Main ): Input, data= [ 0x00 ] 0
Data Array Absolute No_Wrap Linear
Preferred_State No_Null_Position
Non_Volatile Bitfield
Item(Local ): Usage, data= [ 0x02 ] 2
(null)
Item(Global): Logical Minimum, data= [ 0x00 ] 0
Item(Global): Logical Maximum, data= [ 0xff 0x00 ] 255
Item(Global): Report Size, data= [ 0x08 ] 8
Item(Global): Report Count, data= [ 0x08 ] 8
Item(Main ): Output, data= [ 0x02 ] 2
Data Variable Absolute No_Wrap Linear
Preferred_State No_Null_Position
Non_Volatile Bitfield
Item(Main ): End Collection, data=none
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 1
Device Status: 0x0000
(Bus Powered)
--------------------------------------------
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