Problem with RAC_INT


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  1. #1

    Default Problem with RAC_INT

    Hello again,
    Thanks to DT's advice I was able to get my elapsed timer test program working well. I modified the original Elasped_INT routine in order to keep track of time in seconds and tenths of seconds to suit my purpose. My test circuit using this program worked perfectly, with good accuracy when checked against a stopwatch.

    However, when adding another interrupt source there was no response from the breadboard circuit. The new source was RAC_INT, interrupt on portA change. The circuit has switches on several portA pins. Input changes on the pins was verified, but the test progarm did not respond as expected.

    Code:
     '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    
    
    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
    
    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:
       low led              'turn led on
       pause 2000        'pause 2 seconds
    @ INT_RETURN
    '---------------------------------------------
    halt: end
    427 words

  2. #2

    Default

    Your timer interrupt is firing 10 times a second, which means your "RDT" routine can never complete with a 2 second pause. Try polling the switches in your "main" loop, instead of using a second interrupt. You should have plenty of time.

    Regards

  3. #3
    Join Date
    Jul 2003
    Location
    Colorado Springs
    Posts
    4,959

    Default

    Code:
    '-------Interrupt Handler for RDT------------
    RDT:
       low led              'turn led on
       pause 2000        'pause 2 seconds
    @ INT_RETURN
    With any of the PORT change interrupts, you have to Read the port inside the handler to end the "mismatch" condition.
    Otherwise DT_INTS can't reset the int flag, and it will lock up in a continuous interrupt loop..
    DUMMY = PORTA
    <br>
    DT

  4. #4
    Join Date
    Jul 2003
    Posts
    2,405

    Default

    Ditto - and you might want to have something in your interrupt handler that waits for the input pin to return to the idle state before exiting your interrupt handler.

    I.E. if your button press takes the pin low, to generate the interrupt, wait for it to return high before exiting. Otherwise you'll have interrupts on button press & release.
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com

  5. #5

    Default

    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.

    Code:
    '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

  6. #6
    Join Date
    Jul 2003
    Posts
    2,405

    Default

    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.
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com

  7. #7

    Default

    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 ...

  8. #8
    Join Date
    Jul 2003
    Posts
    2,405

    Default

    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.
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com

  9. #9
    Join Date
    Feb 2010
    Posts
    15

    Default

    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?

  10. #10

    Default

    Files attached. Rename without .txt to use.
    Attached Files Attached Files

  11. #11
    Join Date
    Feb 2010
    Posts
    15

    Default

    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

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