I am writing some code for an Arduino pro micro (ATmega32u4) to monitor an SRX encoder. Yes, I had to use direct port access to get it fast enough. In any case, I am trying to backtrack the absolute position at the time I started sampling the quadrature encoder so that I have an absolute position from beginning of sampling.
Inspecting the results, I see that the voltage rises are evenly spaced (so I think of these as the clock pulses), and the voltage falls are based on angle (I think of them as the data pulses). The documentation clearly indicates that the time between the rise and fall on the absolute/PWM pin is typically 1 μs * (encoder position + 1), where the encoder position is in the range 0…4095.
The question is: **when **is this encoder position measured? My working guess is that it is taken as the rising pulse is sent, give or take a microsecond.