--- In "fabianmejia" <> wrote:
>
> Hi All,
>
> I am under development of a capture system. I need to sample about
> 200Hz. That is, about sampling each 0.005 seconds.
>
> I have it working using the Jim Jackson's adc_logger.
>
> Unfortunatelly, this can't accomplish the job as it's accurate about 10ms.
>
> So, I decided using gettimeofday. Oh surprise!!! It doesn't work
> properly. microsecond precision? Forget about it. Readings give me
> mumbers like this:
>
> 510000
> 530000
> 550000
>
> It sounds like 10msec precision.
>
>
There is an alternative that may be suitable. The nanosleep libary call will
do busy-loop
wait when invoked with a duration less than the tick interval. This allows you
to go down
to microsecond resolution, but your CPU usage will be be a nice level 100%, and
other
programs may or may not get a look in. PS -you also have to set your processes
scheduling prority to one of the realtime classes - SCHED_RR or SCHED_FIFO.
Martin
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