Re: High stepper rate troubles

[Jon Elson <jmelson-at-artsci.wustl.edu>]

John Weismiller wrote:

> Hello,
>
> I tried changing the PERIOD, but this did not help.  I tried both
> increasing and decreasing the value.  I tried 0.000008, 0.000048 and even
> 0.00048.  I think that the default value should be okay, as the system is
> a Celeron 433.
>
> I also tried freqmod but all I could get is axis following errors.  I
> changed the P to 60 and default and max accel. in the [TRAJ] section to
> 1.5 as recommended in one of the posts on this list.  It would slowly get
> to about 0.0012 and then give the error.  I also noticed the mbuff
> problems when using freqmod.o.

Well, you are getting close, if it takes a while to hit the following
error.  Try turning P up to, say, 100.  Or, turn the accel down a little more,
maybe 1.2 or 1.0  That may be all the acceleration you should expect with
steppers, anyway.

> When using steppermod.o, everything works fine if I set the INPUT_SCALE
> for each axis to 20000.  It's only when I change it to 40000 that it
> causes the computer to crash.
>
> I have been reading through the source code, and I noticed that the
> period of the stepper motor task seems to linked to both the input scale
> and the max velocity.  Is this correct?  I tried changing the
> MAX_VELOCITY, but that did not help.  Can anybody tell if I am on the
> right track?

steppermod is really obsolete, as it has gross problems with large velocity
jumps at the higher speeds.

Jon