Interupt driven servo PWM output

[mark_s]

From a quick look at your code. I don't see where your intererupt calls
"SERVO_HANDLER:". Also the endif's after @ INT_RETURN will never be executed since the program will return before hitting the end if. I can't analysis your code fully but I would restructure it. I did a quick cut and paste on your code. Untested it may get you going

SERVO1 VAR LATD.0
SERVO1POS VAR BYTE
PRELOAD1 VAR WORD
PRELOAD2 VAR WORD
PRELOAD3 VAR WORD
SERVOCMDMODE VAR BYTE
SERVOPWMCOUNTER VAR WORD

PRELOAD1 = 63556                                                                ' 990us   '63556
TMR0_CON_PL1 CON %10000010                                                      ' 1:8
PRELOAD2 = 65528                                                                ' 4us     '65528
TMR0_CON_PL2 CON %10000010                                                      ' 1:8
PRELOAD3 = 29556                                                                ' 17990us '29556
TMR0_CON_PL3 CON %10000010                                                      ' 1:8
SERVOCMDMODE = 1
'____________________________________________________________
@ INT_ENABLE TMR0_INT
TMR0L = PRELOAD3.LOWBYTE
TMR0H = PRELOAD3.HIGHBYTE
T0CON = TMR0_CON_PL3
SERVO_HANDLER:
IF SERVOCMDMODE = 2 Then
    IF SERVOPWMCOUNTER < 256 THEN
        T0CON = TMR0_CON_PL2
        TMR0L = PRELOAD2.LOWBYTE
        TMR0H = PRELOAD2.HIGHBYTE
        IF SERVO1POS < SERVOPWMCOUNTER THEN
            SERVO1 = 0
            LATD.1 = 0
            LATD.2 = 0
            LATD.3 = 0
        ELSE
            SERVO1 = 1
            LATD.1 = 0
            LATD.2 = 1
            LATD.3 = 0            
        ENDIF
        SERVOPWMCOUNTER = SERVOPWMCOUNTER + 1
    ELSE
        T0CON = TMR0_CON_PL3
        TMR0L = PRELOAD3.LOWBYTE
        TMR0H = PRELOAD3.HIGHBYTE
        SERVO1 = 0
            LATD.1 = 0
            LATD.2 = 0
            LATD.3 = 1
        SERVOCMDMODE = 1
    ENDIF


IF SERVOCMDMODE = 1 Then
    T0CON = TMR0_CON_PL1
    TMR0L = PRELOAD1.LOWBYTE
    TMR0H = PRELOAD1.HIGHBYTE
    SERVOCMDMODE = 2
    SERVO1 = 1
    LATD.1 = 1
    LATD.2 = 0
    LATD.3 = 0
    SERVOPWMCOUNTER = 1
ENDIF

@ INT_RETURN 
'______________________________________________________________
MAIN:
SERVO1POS = 0
PAUSE 5000
SERVO1POS = 128
PAUSE 5000
SERVO1POS = 255
PAUSE 5000
GOTO MAIN

END