RPI4 Raspbian 64 bit & LinuxCNC

Base thread gave me error so i used servo thread :

GPIO working as expected



sorry for dog noises.

Verry cool!
If you installed gpiod, can you remove it and retest?
sudo apt remove gpiod
I was going to add gpiod to the image but if it works without it there is no need and the last image can be a final for a while.
We will leave the installer on 2.10 branch for now. Hopefully,  Andy can backport the driver to 2.9 branch before 2.9 is released.

I did not install gpiod. image missing /media/kunena/emoticons/cool.png

I think you'd have to spend some time working on latency to run a base thread to run steppers from the GPIO.

Maybe with a decent sd card, 3 cores isolated and a base thread of 30k to 40k you may have luck.

I did my testing on a Pi400 with a 10kHz base thread. With the reset function you can still get to 750rpm with 4x microstepping on a 200 step motor.

andypugh wrote:

I did my testing on a Pi400 with a 10kHz base thread. With the reset function you can still get to 750rpm with 4x microstepping on a 200 step motor.

I don't understand why people insist on using a base thread on the Pi. It has a 54 Mhz timer frequency so that means  using a simple square wave, the maximum frequency  is 27 Mhz. We should be driving it like a Mesa stepgen.

I have run steppers on an Arduino this way.   To program a pulse with say 10 usec to write to a port and the same for the time for the end of a pulse, (total 30 usec), you should be able to get up to 33 kHz without a base thread. (if my maths is right) Which gives you about 1000 rpm on 10 x microstepping. MOst motors give up at 750 rpm