MESA 7i76e Stepgen Frequency

Hi everyone,
I've been working with a MESA 7i76e for a while now and I'm actually quite experienced (or so I would say image missing /media/kunena/emoticons/wink.png).

Now I am expanding my machine with an A-axis. I would like to drive the motor with 100kHz. At 50 kHz (MAX_VELOCITY=625) everything still runs well. But when I go to 100kHz (MAX_VELOCITY=1250), I get a position error that I can't explain. The MESA card should not have any problems here yet.

Does anyone want to help? Maybe it sounds familiar to someone.

Thanks in advance

It may be a setup error of some kind (7I76E stepgens are capable of generating
step rates of more than 10 MHz)

You may need to plot the following error + velocity with halscope to debug this


This might be an issue:

setp pid.a.maxerror 0.012700
(= .0127 degree)

That's only ~1/100000 of dynamic range for the A axis PID loop so might be less
than the LinuxCNC/7I76E clock differences.

Just tried setting the maxerror to 100 and got the same error.

The first professional screenshot shows the behavior at 50kHz, the second at 100kHz. As if the Stepgen or PID suddenly stops at a certain frequency.

image missing /media/kunena/emoticons/unsure.png

A screenshot is smaller and much more legible than a photo

You're right, of course. I couldn't have done any better at that moment.