Hi Richard,

The profile generator will generate the moving target setpoint that the PID filter servos the motor to, output of PID filter goes to PCPWM module which drives the H-bridge. Everything running on the same PIC. (Step/dir signals could also provide the moving target setpoint TO the PID filter (bypassing the profile generator) but for this project I'm not interested in generating step/dir signals.)

I think that generating a step/dir based profile would actually be easier (though generating step pulses at any decent frequency isn't easy on a PIC) because then you are basically controlling the motor down to the individual step level. For each "tick" you either issue a step or you don't so it's easy to "hit" the exact spot where deceleration needs to start in order to get to the target position without violating any of the settings.

When doing the profile generation, PID, PWM and feedback in the same PIC it's not as easy since the motor is moving more than a single count for each "tick". You tell the motor to move an arbitrary amount of counts per "tick" which so you're likely to overshoot the "sweetspot" where you need to start decelerating.

I hope that makes sense.

/Henrik.