Issue with inconsistent spindle RPM readings on Mesa 7i76e + LinuxCNC setup

Hey everyone,
I’ve been setting up a CNC mill using LinuxCNC with a Mesa 7i76e board, and I’ve run into a bit of a headache. The spindle RPM readings in the LinuxCNC GUI are fluctuating a lot even when the spindle speed seems stable when measured with an external tachometer. I'm using an encoder on the spindle for feedback, but I’m not sure if the issue is from signal noise, encoder settings, or something else in the HAL config.Has anyone else had similar issues with inconsistent RPM readings? What would you recommend checking first encoder wiring, debounce filtering, or maybe even firmware updates for the Mesa board? Any guidance would be a huge help, I’m still getting comfortable with HAL and custom configs.Thanks in advance!

References:

www.theengineeringprojects.com/2023/06/i...l-with-linuxcnc.html
www.cnczone.com/forums/linuxcnc-formerly-emc2-/
store.mesanet.com/index.php?route=product/product&product_id=58

It could be a wiring/noise issue but typically this is because of the relatively
instantaneous velocity estimation (typically updated every ms), which tends
to accentuate the encoder inaccuracies. This fast update is important if a feedback
loop is used but a nuisance for a human readable display.

The way this is typically fixed is by low pass filtering the encoder velocity signal
before displaying it. If this has already been done, you might increase the time
constant of the filter