Interupt driven servo PWM output

[comwarrior]

ok, here is the full code... i didn't think the top bit was necessary...

@ __config _CONFIG1H, _FOSC_INTIO67_1H & _PLLCFG_ON_1H & _PRICLKEN_ON_1H & _FCMEN_OFF_1H & _IESO_OFF_1H
@ __config _CONFIG2L, _PWRTEN_ON_2L & _BOREN_SBORDIS_2L & _BORV_220_2L
@ __config _CONFIG2H, _WDTEN_OFF_2H & _WDTPS_32768_2H & _CCP2MX_PORTC1_3H & _PBADEN_OFF_3H
@ __config _CONFIG3H, _CCP3MX_PORTE0_3H & _HFOFST_OFF_3H & _T3CMX_PORTC0_3H & _P2BMX_PORTC0_3H & _MCLRE_INTMCLR_3H
@ __config _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _XINST_OFF_4L & _DEBUG_OFF_4L
@ __config _CONFIG5L, _CP0_OFF_5L & _CP1_OFF_5L & _CP2_OFF_5L & _CP3_OFF_5L & _CP1_OFF_5L & _CP2_OFF_5L & _CP3_OFF_5L
@ __config _CONFIG5H, _CPB_OFF_5H & _CPD_OFF_5H
@ __config _CONFIG6L, _WRT0_OFF_6L
@ __config _CONFIG6H, _WRTC_OFF_6H & _WRTB_OFF_6H & _WRTD_OFF_6H
@ __config _CONFIG7L, _EBTR0_OFF_7L & _EBTR1_OFF_7L & _EBTR2_OFF_7L & _EBTR3_OFF_7L
@ __config _CONFIG7H, _EBTRB_OFF_7H

INCLUDE "DT_INTS-18.bas" ; Base Interrupt System
INCLUDE "ReEnterPBP-18.bas" ; Include if using PBP interrupts

ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
INT_Handler TMR0_INT, _SERVO_HANDLER, PBP, yes
endm
INT_CREATE ; Creates the interrupt processor
ENDASM

Define OSC 64 ' Set clock speed

OSCCON.7 = 0
OSCCON.6 = 1
OSCCON.5 = 1
OSCCON.4 = 1
OSCCON.1 = 0
OSCCON.0 = 0
OSCTUNE.6 = 1

ANSELA = %00000000
ANSELB = %00000000
ANSELC = %00000000
ANSELD = %00000000
ANSELE = %00000000

TRISB = 0
PORTB = 0
TRISC = 0
PORTC = 0
TRISD = 0
PORTD = 0
TRISE = 0
PORTE = 0
TRISA = 0
ALOOP VAR WORD

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

@ INT_ENABLE TMR0_INT
TMR0L = PRELOAD3.LOWBYTE
TMR0H = PRELOAD3.HIGHBYTE
T0CON = TMR0_CON_PL3
SERVOCMDMODE = 1

MAIN:
SERVO1POS = 0
PAUSE 5000
SERVO1POS = 128
PAUSE 5000
SERVO1POS = 255
PAUSE 5000
GOTO MAIN

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
@ INT_RETURN
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
@ INT_RETURN
ENDIF

@ INT_RETURN

[HenrikOlsson]

Hi,
OK, so you're running at 64MHz, that gives it bit more time but I still think that interrupting at 4us intervals is way to fast, there's only 64 instruction cycles between each interrupt and I think it takes more than that for the DT-Ints system just to save and later restore the system variables. And, even if it does work the code would spend most of its time in transit to and from the interrupt handler.

/Henrik.

[LettyLocke]

The time between transit and interrupt handler is the main culprit here in your servo pulse width modulation. Sometimes the turn around time makes us wait more and it doesn't work in the end even though everything seems right. Happens with me all the time. Connected a lipo battery once as a power supply and it never worked because of misconfiguration.
Good luck to you.

[LettyLocke]

The time between transit and interrupt handler is the main culprit here in your servo pulse width modulation. Sometimes the turn around time makes us wait more and it doesn't work in the end even though everything seems right. Happens with me all the time. Connected a lipo battery once as a power supply and it never worked because of misconfiguration.
Good luck to you.

No more updates regrading the issue? I think the interval time of interrupts must be increased in order for it to work. Interrupt handlers are very tricky to work with.

[Acetronics2]

some pointers ???

http://www.mikroe.com/forum/viewtopic.php?f=10&t=7081

Alain