[libhid-discuss] Help on libhid - Accelerometer

[Charles Lepple]

On Mar 10, 2008, at 11:53 AM, domenico at terminus.it wrote:

>> Basically, it should not be sending a report ID if there
>> are no   report IDs defined in the HID report descriptor
>> (note that it says   "length: 6" but you passed in an
>> array of 5 bytes).
> What do you mean for report ID? The message to be sent to
> device?

You may want to check here for terminology:

http://www.usb.org/developers/devclass_docs/HID1_11.pdf

(Page 27 describes report IDs.)

> But before sending report, I can't find the item-address to
> send to:
>
> WARNING: hid_find_object(): can't find requested item
> 0xff000001.0x00010046.0x000a0001 of USB device
> 002/002-1b67-000a-00-00[0].

You may have found a bug in the hidparser code. It shouldn't print  
the path to a node that it can't find (although the paths ending in  
0x00000000 are just extra bytes for the first HID report element).

At the moment, I can't really debug this, since libhid only operates  
on live devices. One of my TODO items is to have a mode where libhid  
can read a HID descriptor captured on another computer.

-- 
Charles Lepple