I posted something I thought might be helpful since it seemed to fix my problem but, then it started happening again. My SPI interface keeps getting reset as well and only when my spindle gets turned on. I already created a shielded cable between the SPI connections. I thought messing with the base servo speed helped in the ini file at one point but, I just tried again and got the same microcontroller reset. After that I have to reset the microcontroller before I get a good status signal for the SPI connection and I can toggle machine power once again and communications work as well. I guess it could be interference on the SPI interface still but, I'm not sure how that is happening. EDIT: I guess after creating a shielded SPI cable it did work for longer before getting an SPI reset. I still had issues and I just put a piece of tin foil over no directly onto the raspberry pi4 GPIO pins and it looks like all of my errors are gone so maybe some EMI was getting into the raspberry pi pins and resetting the controller somehow? I'm still testing to see if my problem is gone for good but, fingers crossed.