Re: [Libusb-win32-devel] devices list is empty on Windows x64

[Martin K <mar...@gm...>]

On Mon, Apr 11, 2011 at 8:15 AM, Xiaofan Chen <xia...@gm...> wrote:
> On Mon, Apr 11, 2011 at 7:22 PM, Martin K <mar...@gm...> wrote:
>> On Sat, Apr 9, 2011 at 7:42 PM, Xiaofan Chen <xia...@gm...> wrote:
>>> As for "unknown device", it can be hardware or firmware problem.
>>> Please post to Microchip forum here for more help. You
>>> may need to post your schematics there for hardware check.
>>> http://www.microchip.com/forums/f102.aspx
>>>
>> I believe it's safe to say that "unknown device" is a firmware
>> problem. It's not communicating at all, but the computer knows
>> something is there (pullups)
>
> This may not be true. "Unknown device" can well be a hardware
> problem, for example, the clock is not stable or things like that.
> Actually in the Microchip forum, the No 1 enumeration problem
> for USB PIC18 is to forget about the Vusb capacitor (typically
> 470nF), No 2 being the improper clock configuration.
>
> Reference:
> http://www.microchip.com/forums/fb.ashx?m=335717
>
> --
> Xiaofan
>

If you're dealing with newbies I suppose. Both of those are very well
documented in the data sheet. I don't want to go down this road
though. I'll just point out that it's only ever been a firmware
problem for me.

-- 
Martin K.