[Ether]

Originally Posted by iambujo

The AMT10 has a configurable resolution ranging from 48 up to 2048 at a max of 7500 RPMs

Assuming¹ for the moment that 2048 means "rising edges per rev per channel", let's do the math if you set this up for quadrature at 7500 RPM with a 20ms control loop period:

CPR: 2048$

decoding:4$

secondsPerControlLoop: 20/1000$

FPGAsamples: 127$

edgesPerControlLoop: RPM * (1/60) * (decoding*CPR) * secondsPerControlLoop = 20,480

secondsPerEdge²: float((1/RPM) * 60 * 1/(decoding*CPR)) = 0.9766e-6

secondsPerSamplesize: secondsPerEdge * FPGAsamples = 0.1240234375e-3

As can be seen, that is way overkill for operation at that speed.



¹ I am inferring that because there are a couple of odd-number PPRs in the list, namely 125 and 385. You can't have an odd number of "rising and falling edges per rev per channel" or "rising and falling edges per rev both channels"

² This number is even smaller if quadrature tolerance is included. But the 40MHz sampling rate of the roboRIO theoretically should handle it.