cattledog:
I'm actually of the opinion that your encoder reading is correct, and there are issues with your how you are trying to validate its performance. Moving a wheel back and forth to see if you can be accurate to .0015 is not something to eyeball. If you come to a hard stop and zero the count, and then move out to another stop(or some number of index pulse interrupts) is the count repeatable for multiple measurements in the same direction?
I will try tomorrow and zero at each stop see if i get the same counts in each direction. As to zeroing and starting at one stop and going from one stop (hard stops) to the next back and forth the results are shown in my previous reply
Start 0.0000
Max 57.6933
Back again 0.0030
57.6872
-0.0045
57.6621
-0.0121
57.6631
-0.0272
57.6510
-0.0408
Ill also try paul stoffregen sample program to just see if the pulses add up when sliding from one hard stop to the next.