What bandwidth was requested from the system? Any desired performance specs?
On Monday, August 09, 1999 2:58 AM, SteenbeckDigital
[SMTP:[EMAIL PROTECTED]] wrote:
> Nachricht geschrieben von Tomasz Motylewski
> >
> On Mon, 9 Aug 1999, SteenbeckDigital wrote:
>
> > Tryed the example with a 300MHz Pentium and
> > could hear the machines load from the servo.
> > Using a professional RC-servo I could
> > even see the machines load.
> > The jitter is slightly to big for this.
> > This shows the limit of RtLinuX.
>
> What jitter did you expect? You will not get below 1 us with any program
> running on a PC Intel x86 withiout some special hardware.
>
> If you want to reach 1 us limit, you need to schedule your interrupt about
> 20-30 us before the deadline and then wait reading the clock counter - I
> guess you do the same when you really want to catch the train :-)
>
> Expect 5-10 us jitter with standard RT-Linux.
> <
>
> ############################
> I didn't expect something different.
> Just mentioned it to the group so not everybody
> runs into trouble relying on RC-servo control.
> Would be interested if polling the time could
> fix the jitter for this application.
> ############################
>
> Stuart Warren wrote
>
> I tried this myself and didn't have any trouble. That was on a P123 and
> RTL V1.0 For a while there I thought I had a problem with the timing
> accuracy but it ended up being my power supply not being able to handle
> the load of the servos.
>
> #############################
> - For my test I took the power from an extra power supply.
> - Where did you get the P123 from???
> - What kind of RC-servo did you use??
> Only the slow servos didn't show the symthom to me.
> The fast one showed the jitter very good.
> - Is there a patch to RtLinuX where the jitter has been reduced??
> #############################
>
> Jens Michaelsen
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