Re: Report ID problem with HID-RAW interface usage

[Alan Ott <alan-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org>]

On 07/02/2010 02:46 AM, Amit Nagal wrote:
>> 1. Your device has lots of reports, which all take the same type of data.
>>      
> Yes . the device has lots of inputs and output reports .
> the report values are<command>  <  response>  only .
>
>    
>> 2. Each report differs _only_ in its length, but the data is the same. For
>> example:
>>         1. If you want to send 5 bytes to the device, you use report 1, which
>> is 5 bytes long
>>         2. If you want to send 10 bytes to the device, you use report 2,
>> which is 10 bytes long.
>>         3. if you want to send 20 bytes to the device, you use report 3,
>> which is 20 bytes long.
>>         etc.
>>      
> Yes. exactly . data  payload len is the defining parameter to
> determine the report N to use .
>    

I'm going to challenge this. I looked at the report descriptor you 
attached, and I don't think it really works the way you think it does. 
What it looks like to me is separate reports expecting separate data, 
not a bunch of reports all expecting the same data but of different 
lengths. What you describe would be fairly non-standard, IMO.

What I would suggest for the short-term is this:
With the device you have, send data based on the HID descriptor you 
attached to the last email. I mean manually. In the case of your 
descriptor: if the report length you want to send is <= 5, use report 1; 
If it's <= 9, use report 2; if it's <= 13, use report 3; if it's <= 17, 
use report 4; if it's <= 25, use report 5, etc.

This will allow you to say for sure that it works the way you think it 
does. If it does, then you're right, (and I'm wrong :) ). I'm betting 
though, that it won't, and that each report is expecting different types 
of data than all the other reports.

Does this sound like a reasonable approach to the rest of you guys?

Alan.



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