Interrupt On both (Rising and Falling)


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  1. #1

    Default Interrupt On both (Rising and Falling)

    Hi to all.
    In my project I've used external interrupt. Rising edge on RB0 causes to occure an Interrupt. In the ISR, data are read from serial EEPROM. I've used a micro switch for determining the direction of movement. For example rising edge (1 to 0) implies right direction and falling edge (0 to 1) left direction. I need both of edge change detection. It means that in right direction should be done one thing and in left direction another thing. Unfortunately I can only detect one of directions: right or left! (By setting of OPTION register). How can I determine direction of movement?
    At the first I wanted to implement it by PORTB chane interrupt (RBIE). I defined all of pins of portB as output except for RB0. But it didn't work and it was so unstable.
    Please help me.
    Thanks alot

  2. #2
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    Wink

    Hi,

    Look at your available interrupts list ...

    Does "change on Port B" seem familiar ???

    Go on ...

    Alain
    ************************************************** ***********************
    Why insist on using 32 Bits when you're not even able to deal with the first 8 ones ??? ehhhhhh ...
    ************************************************** ***********************
    IF there is the word "Problem" in your question ...
    certainly the answer is " RTFM " or " RTFDataSheet " !!!
    *****************************************

  3. #3


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    Default Good but HOW?!!

    Hi Acetronics. Thanks for your reply. As I said I wanted to use Interrupt from "Change on portB", but it didnot work. I use PIC16F84 in my project so I should optimize use of pins. I defined all of pins of PORTB as output except for one of them. I connected a push button to that. It didnot work normally. Why? Can you help me? How can I do that? Have you any example of method of using Change on port B interrupt?

  4. #4
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    Question My car doesn't start - Why ???

    Hi,Yasser

    First , In the title , understand we do not know at all what you did ( hardware ) nor what you wrote ( software ) ... and there are no "crystal ball" option on this forum ...

    For the car ... " did you insert the key ??? " is a first question to consider ...


    ...

    There's a funny thing in this feature ... the "end of mismatch" condition.

    I think there were ( numerous ) threads about that on this forum. ( a SEARCH will be useful ...)

    ... in a word, you have to READ PortB in your interrupt stubb to get it that interrupt working properly ( see examples given ...)

    BUT, as always ... only knowing which processor and compiler ... leaves NUMEROUS non-working reasons ...

    Alain
    ************************************************** ***********************
    Why insist on using 32 Bits when you're not even able to deal with the first 8 ones ??? ehhhhhh ...
    ************************************************** ***********************
    IF there is the word "Problem" in your question ...
    certainly the answer is " RTFM " or " RTFDataSheet " !!!
    *****************************************

  5. #5


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    Default My car has unknown problem!!

    Thanks alot dear Acetronics.
    I wrote this simple program for testing portB change interrupt.

    '************************************************* ****************
    '* LCD Deifnes *
    '************************************************* ****************

    DEFINE LCD_DREG PORTD ' I/O port where LCD is connected
    DEFINE LCD_DBIT 4
    DEFINE LCD_RSREG PORTD
    DEFINE LCD_RSBIT 2 ' Register select pin
    DEFINE LCD_EREG PORTD
    DEFINE LCD_EBIT 3 ' Enable pin
    DEFINE LCD_BITS 4 ' 4-bit data bus
    DEFINE LCD_LINES 2 ' LCD has 2 character lines

    '************************************************* ****************
    '* Interrupt Initialzing *
    '************************************************* ****************

    INTCON = %10001000 ' GIE and RBIE are set
    OPTION_REG = %10000000

    '************************************************* ****************
    '* Initialzation *
    '************************************************* ****************

    TRISB = %00010000
    PORTB = 0

    ON INTERRUPT GOTO DIRECTION

    '************************************************* ****************
    '* Main Program *
    '************************************************* ****************

    MAIN:
    lcdout $fe,1
    lcdout "Main Routine"
    pause 500
    GOTO MAIN
    END

    '************************************************* ****************
    '* Interrupt Service Routine *
    '************************************************* ****************

    DISABLE
    DIRECTION:
    lcdout $fe,1
    lcdout "Interrupt !!!"
    PAUSE 100
    INTCON.0 = 0
    RESUME
    ENABLE

    I compiled it and downloaded HEX file to PIC. I use PROTEUS 6 pro for simulating my program.(My Circuit Attached) When I pushed start debugging button on
    proteus an unusual thing happened. I think that program should work in main loop so "Main Routine" should be written on LCD! But as soon as program starts
    executing, the message "Interrupt !!!" is shown on LCD!! even if the push button isn't pressed. Why it does not work correct?!!

    You wrote for me: "... in a word, you have to READ PortB in your interrupt stubb to get it that interrupt working properly ( see examples given ...)" What do you maen? Could you tell me about given examples?
    ** Although I use PIC16F877 in this simulator, I want to use PIC16F84 in my project. **
    Attached Images Attached Images  

  6. #6
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    Default

    Do you know what the inital value of port B is in order to detect a change on said port B?
    Are all of your Port B pins pulled high/low or whatever?
    Are any of them floating? open?

    2nd thought...get rid of the simulator and build some real hardware...

  7. #7
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    Wink

    Hi, Yasser

    I'll give a try on my test board : 16F84 + LCD ...

    Alain
    ************************************************** ***********************
    Why insist on using 32 Bits when you're not even able to deal with the first 8 ones ??? ehhhhhh ...
    ************************************************** ***********************
    IF there is the word "Problem" in your question ...
    certainly the answer is " RTFM " or " RTFDataSheet " !!!
    *****************************************

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