Alternative to digital rotary encoder

[backflip]

@DaveX

A 1000 line encoder using interrupts on a 30RPM shaft can deliver 2kHz pulses/sec by triggering on all 4 rising and falling changes of the A&B signal lines, and you can trim it down to 1kHz by configuring the interrupts to just trigger on A changes or 500Hz with just A falling. At 30000RPM, you could use and ABZ encoder and switch over to triggering off of the index pulse, or run the AB signals through a divider. With some adaptive coding and a 1000PPR ABZ encoder you could handle a range from 15RPM to 30000RPM with interrupts between 1kHZ to 30kHz with some tradeoffs between resolution and speed. With some hardware dividers you could extend that RPM coverage further.

I guess, that it would be possible, but it do not seam easy like just reading the voltage from a DC tacho generator as shown above. I do not think, that the specific time between each edge of the two digital outputs from the encoder would be the same. So each of the four transitions timing would need to be calibrated individually.

Just now I use timer1 of the Arduino Nano for 20 kHz PWM to motor and control of ADC for current measurement. How can other timers be used to measure the time between transitions? Could you provide some link to an encoder, that you might suggest?

I should like to get a bit closer on how it is done, and how accurate it might be in the speed range. I think it can be hard to rely on interrupt routines to measure some timing, and therefor some hardware timer solution is needed to measure the time between these edges from encoder.