You can get pretty far nowadays with preempt rt and an FPGA. Maybe you even can get near 1µs max jitter. One problem with the older RPis was unpredictable (to m

You can get pretty far nowadays with preempt rt and an FPGA. Maybe you even can get near 1µs max jitter. One problem with the older RPis was unpredictable (to me) behaviour of the hardware, i.e. "randomly" changing SPI clocks, and limited bandwidth. Hobby systems like a small CNC mill or lathe usually don't need anything near 1µs (or better) max jitter. LinuxCNC (derived from NIST's Enhanced Machine Controller, name changed due to legal threats) runs fine on preempt-rt with control loops around 1kHz, with some systems you can also run a "fast" thread with say 20kHz and more to generate stepper motor signals, but that job is best left for the FPGA or an additional µC IMHO.