On 08/02/2011 22:33, Joe Koberg wrote:
>> Joe Koberg wrote:
>>> http://s3.ae5ne.com.s3.amazonaws.com/dspic33_bad_sinewave.pdf
>> I have no idea what you're trying to do and what this waveform is suppos=
ed
>> to look like.  However, this looks very much like high bits wrapping
>> somewhere.  That could be due to overflow or improper handling of signed
>> versus unsigned integers, for example.
>
> Just for added detail, here is a capture containing "at least one"
> complete cycle without a glitch.  To me this indicates the table is
> being indexed properly (and the counter is wrapping OK), and that the
> table values are valid.
>
>       http://s3.ae5ne.com.s3.amazonaws.com/dspic33_bad_sinewave2.pdf
>
>
> FYI the PC scope software is OSQOOP from
>
>
> http://www.eig.ch/fr/laboratoires/systemes-numeriques/projets/osqoop-l-os=
cilloscope-libre/index.html
>
> Joe
>
>

Looks like it may be a software problem then - I used OSQOOP a while=20
back (while looking  at open source possibilities for basing scope=20
software on) Anyway, I remember vaguely the trigger could be a little=20
fussy (it expects streaming data and in my case I was sampling at >>USB=20
speeds so had to "trick" it a bit) Took me a little while to  get the=20
wave displayed correctly. Other random thoughts are that it may not be=20
interfacing with your soundcard correctly (IIRC it has plugins for=20
various sources), the buffer is overunning etc.
Just seen your next mail - Audacity is a good move, glad it's fixed now...



--=20
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