PID-filter routine (2nd try).

[phoenix_1]

I runing your PID rutine in 18F4431 and output is locked antiphase , all work like you explain me . I use two interrupt's one for position reding - QEI module and second to calculate PID , in main loop is only increment of setpoint. No Usart , no DEBUG or LCDOUT.
From time to time not a linear in time it have some little noise which I can also see with scope in PWM out and I can't image from where is ?
Simple motor have jig - agitation in range of couple step's to +/- and after couple next step's it go linear.
I use only CW rotation not CCW all the time and PID becouse it good magnetic and precise break in position.
Can it be from bad tuning of P,I,D parameter's ?
Output amplifier is copy of HP UHU with 4 x IRF540N.
Simple I am lost - it is not disaster but meke me little problems on my machin.
Best regards
\ ROBERT