Re: hidapi: does not retrieve serial number of device on macos x

[Alan O. <al...@si...>]

On 04/24/2013 10:27 AM, Folkert van Heusden wrote:
>>> I ported clewarecontrol to hidapi and all runs fine on linux.
>>> On macos x, though, it doesn't show the serial number. This is rather
>>> essential as it is needed to distinguish what device to control when you
>>> have multiple connected.
>>> The hidtest program included in hidapi doesn't show the serial either:
>>> The serial number ought to be 900705 (decimal) or DBE61 (hex).
>> It's worth noting that the serial number is a string descriptor,
>> containing a Unicode string, UTF-16 encoded. Sticking random bytes in it
>> may be causing the UTF-16 parser in the Apple kernel/libraries to bail
>> somewhere. That's my first guess since it seems to work for others.
> The code of the (original) cleware c++ library does:
>
>                                         int strInc = (s[1] == 0) ? 2 : 1 ;
>                                         for ( ; *s ; s+=strInc) {
>  // unicode byte 2 == 0
>                                                 if (*s >= '0' && *s <= '9')
>                                                         SerNum =
> SerNum * 16 + *s - '0' ;
>                                                 else if (*s >= 'A' && *s <= 'F')
>                                                         SerNum =
> SerNum * 16 + *s - 'A' + 10 ;
>                                                 }
>
> So I think that some use plain ascii while others may use UTF-16 (with
> high byte set to 0x00).

You should use the wide character functions. HIDAPI will give you a
wchar_t, with which you could use something like wcstol().

I'm less interested in what the PC-side does than what the firmware
does. Can you send your string descriptor (as a fragment of your firmware)?

Have you tried putting a normal string for the serial number in the
firmware (like hard-coding to "ASDF") and seeing if that makes it
through? Are you able to see serial numbers from other devices?

Alan.