Measuring motor speed

[Ether]

Originally Posted by fovea1959

Ether: we get one count per rev with that magnet. I believe the student had the averaging set to 1

The 6.525 us quantization of the FPGA timing of the period should give you about 38 RPM peak-to-peak jitter at 18,600 RPM with sample size set to 1. That's about 0.2% p-p. Pretty darn good.

I am anticipating doing bang-bang, and frankly, I don't know how fast we'll run it.

Nice thing about bang-bang is it doesn't care much if your control period has jitter. Since the bang-bang code is so minimal, you can run it fast without chewing up much CPU.