Problem with RAC_INT

[Dick Ivers]

Still not clear on how to end the mismatch in porta. Tried the following code, but it did not work on the breadboard. I'm looking for the the led to go off and stay off for 2 seconds, and then the timing to resume. This is just a demo tryout.

All of this is just testing to try to understand how instant interrupts work. Of course I know it's possible to just poll a porta pin in the main loop ... I do it that way with my non-interrupt software.

'device is PIC 16F684

'set registers
        OPTION_REG.7 = 0     'enable porta pullups    
        CMCON0 = 7           'comparators off
        ANSEL = 0            'porta pins all digital 
        TRISA = %111111      'set porta pins as input
        TRISC = %001101      'set portc pins 0,2,3 as input, all others output
        OSCCON = %1110000    'set internal osc. at 8 mhz, wait for stable freq.
        OSCTUNE = 0          'internal osc. running at factory calibration

        DEFINE OSC 8         '8 Mhz oscillator

        while OSCCON.2 = 0   'wait for osc.to be stable
        wend

'declare variables
        led     var portc.3      'led output on portc.3
        DTtime  var word
        sum     var word    
        dummy   var byte

start:   
        low led      'flash red LED for 0.5 sec
        pause 500
        input led  

        pause 2000   'pause 2 seconds
        
INCLUDE "DT_INTS-14 for F684.bas" 'Base interrupt with wsave selected for 16F684
INCLUDE "ReEnterPBP.bas"          'Using PBP interrupts
INCLUDE "Elapsed_INT_RI.bas" 'Elasped timer counting seconds and tenths seconds

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,  _ClockCount,   PBP,  yes
        INT_Handler   RAC_INT,   _RDT,          PBP,  yes
    endm
    INT_CREATE            ; Creates the interrupt processor

    INT_ENABLE  TMR1_INT  ; Enable Timer 1 Interrupts  
    INT_ENABLE  RAC_INT   ; Enable PortA Change Interrupt
ENDASM

dummy = porta             ' initialize dummy variable
DTtime = 1800             ' 180.0 second test
Gosub ResetTime           ' Reset Time to  0d-00:00:00.00
Gosub StartTimer          ' Start the Elapsed Timer

Main:
    low Led               'turn on led
    sum = 10*Seconds + Tenths
    if sum => DTtime then
    high led              'turn off led
    goto halt
    endif
GOTO Main

'-------Interrupt Handler for RDT------------
RDT:
   high led           'turn led off
   dummy = porta      'needed to end mismatch in porta
   pause 2000         'pause 2 seconds
@ INT_RETURN
'---------------------------------------------
halt: end

431 words

[Bruce]

You may need to enable the on-change interrupt for the input pin you're using to trigger
the interrupt. Say you're using RA0, then IOCA0=1 would enable on-change interrupt for
this pin.

Then in your interrupt handler, wait for the pin to return to the idle state before exiting.

Something like WHILE PORTA.0 = 1:WEND. Assuming RA0 was held low, and a switch press
taking it high caused the on-change interrupt.

Interrupt happens on RA0 going high, jumps to int handler, waits for pin to return low before
exiting & re-enabling interrupts.

[Dick Ivers]

Thanks Bruce, your suggestion worked. Setting IOCA.4 = 1 enabled the change on porta interrupt to function properly. I have a switch on porta pin 4. The interrupt works for both on-switching and off-switching.

Of course, each time the interrupt is used 2 seconds is added to the clocked time because of the delay inside the handler. In the real program I don't want this happening. This interrupt will only be used once. After it occurs this interrrupt can be disabled. I then want to jump to another program loop. I'll try some experiments to see if this can be done ...

[Bruce]

Hi Dick,

If the user will not be pressing & holding the switch, then read the port pin after the 2 sec
pause.

Otherwise you need to wait for the pin to return to the non-button-pressed state or it just
interrupts again after the port read & switch release.

If it's a one-shot deal, just disable it by clearing IOCA.4.

[lugo.p]

I intend to use the IOC too, but i'm not sure if i need those:

DT_INTS-14 for F684.bas
ReEnterPBP.bas
Elapsed_INT_RI.bas


if so, where i find this .bas files?

[Dick Ivers]

Files attached. Rename without .txt to use.

[lugo.p]

Thanks Dick but i'm still having troubles with IOCA over 16f684.

Because i have not much experience with PicBasic, i have been reading about IOC but don't understad how to implement a basic interrupt on change