[libhid-discuss] Usage Path Question

[Charles Lepple]

On Oct 2, 2008, at 1:25 PM, Christopher Moore wrote:

> Hey everyone,
>
> I have a question about usage path and formatting a
> hid_set_output/input_report.
>
> Given the output below, I'm trying to:
>
> send a report to:  Report ID #4, I believe the Path to be:
> PATHLEN = 2
> PATH_OUT = [0x000B0001,0x0014002C] or is it [0x0B01,0x142C]?
> SEND_PACKET_LEN = 8

(By the way, if you're using Python, it calculates the length of the  
list/tuple before passing that to the C portion of libhid. So PATHLEN  
is not needed.)

It's the first one - 0x000B0001 etc.

The elements of the usage path are 32-bit numbers, composed of the  
usage page in the upper 16 bits, and the usage in the lower 16 bits.

> receive a report from: Report ID #3 (same as above ... which seems  
> wierd...)
> PATHLEN = 2
> PATH_OUT = [0x000B0001,0x0014002C] or is it [0x0B01,0x142C]?
> RECEIVE_PACKET_LEN = 7
>
> Is my assumption/formatting correct?

I think so.

It's OK to have the same path for inputs, outputs and features. (For  
instance, with a file, you can read or write to it.)

You just have to use the proper function for each item.

-- 
Charles Lepple