I'm looking to count revolutions on a fast (e.g. 2000-4000 RPM) motor output shaft. I can easily put in a couple of optical switches and an interrupt disk. This leaves me pondering quadrature encoding:
- Do I really need to bother with quadrature encoding? Of course you have to for something like an input knob, where the user may turn it in either direction. But in this case, I'm in control of the motor (it goes through a worm gear before getting to user-accessible outputs, so the user won't be able to rotate the motor anyway). Can I simply count the pulses from a single opto switch, and assume that I know which way I'm driving the motor? Or will I run into problems where the motor continues to turn in the old direction for some (unknown) number of pulses after I've told it to reverse?
- Assuming I do need to worry about that, and assuming that quadrature encoding is the best way to go -- can anyone recommend a good (cheap but reliable) quadrature decoder chip? It would need to track something like 100-200 pulses per second, which doesn't seem all that fast in the world of electronics.
I'm a complete newbie to this area, so any pointers or resources you can share would be greatly appreciated.