Interrupts question

[alec]

Hi all
I've been trying to control a triac using an interrupt on RB0 and going to an interrupt handler - been basing it on the discussion surrounding Mr E's lamp dimmer code.

'****************************************************************
'*  Name    : triac_force.pbp                                     *
'*  Author  : Alec Noble                                        *
'*  Notice  : Copyright (c) 2011 Alec Noble                     *
'*          : All Rights Reserved                               *
'*  Date    : 6/18/2011                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
@ DEVICE PIC16F819, WDT_OFF, LVP_OFF, PWRT_ON, PROTECT_OFF, BOD_OFF, INTRC_OSC_NOCLKOUT

    DEFINE OSC           8        ' Set the Xtal frequency to 8mHz
    OSCCON = %01110100
' ** Setup the interrupts   **

INTCON.7 = 1                    'GIE - enable global interrupts
INTCON.4 = 1                    'Enable RB0 interrupt

                               

on interrupt goto AC_detect

      trisa   = %11111111         'Port A all inputs
      trisb   = %00000001         'Port B.0 input,  all others outputs
      
main:
    
    goto main
      




    '
    ' Interrupt routine called by ACLine (RB0) pin state change
    '
disable
AC_Detect:
    pauseus 100
    pulsout portb.1, 25
    INTCON.1=0 ' Clear interrrupt flag
resume
enable

My input pulse train to RB0 is clean - 8.3 ms apart as it should be. However, the output pulses are about 90 MS apart. Am I misunderstanding how to configure the interrupts, doing something else foolish or what? Any help would be appreciated...
Thanks
Alec

[Charles Linquis]

"ON INTERRUPT GOTO" Checks the interrupt flag after each major instruction. My guess is that it is "blind" during the PULSOUT command. If you want PORTB.1 to go high, and stay high whenever there is AC present. This won't do it.

I would use DT-INTS to handle this. Since DT-INTS has an ASM "core", no PBP command can block it.

[jellis00]

Alec, I totally agree with Charles. Don't waste your time with ON INTERRUPT...go download Darrel Taylor's DT_INT at http://darreltaylor.com/DT_INTS-18/home.html . Lot's of help available on this forum for using them.
Regards, John Ellis

[mister_e]

IMHO, and even if I agre with the previous suggestions, it Shouldn't be that messy since you have nothing in the mainloop. Do you have a square wave signal generator (or anything who can produce 50/60 hz with TTL logic level)? try it. If it works, you may have to rethink about your zero crossing circuit.

[mister_e]

Another thing that spring to mind, are you expecting a low to high pulse on PORTB.1 or a high to low pulse?

If you expect a LOW to HIGH, then you should clear PORTB.1 at the beginning of your code, and set it it you expect a High to low one.

It's always a good idea to set the idle state of any PORT pin as the initial state might be unknown.

[Charles Linquis]

But if you simply want to monitor the AC line, then you don't really need interrupts. I'll attach a circuit that (I think) does what you want. The output is LOW whenever there is AC present. The capacitor keeps it from going high during zero-crossings.

And - it has isolation.


The circuit works for both 110V and 220V.