PIC16F877A - Timer0 won't interrupt

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  1. - 14th April 2007, 09:57 #1
    WishMaster^'s Avatar
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    Thanks all for your responds, will try them out on monday, it's weekend now. But thank you all very very much !!!
  2. - 16th April 2007, 07:34 #2
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    It's working perfectly!!! Thanks for the help!

    Cheers,

    William
  3. - 17th April 2007, 08:36 #3
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    Hello all!!
    An update and help request on my program:

    Code:
    define loader_used 1  
define osc 20 

;---Defining Variables---
wsave var   byte $70 system
ssave var   byte bank0 system
psave var   byte bank0 system       

count0  var byte bank0 system
count1  var byte bank0 system
count2  var byte bank0 system
count3  var byte bank0 system  
count4  var byte bank0 system
count5  var byte bank0 system
hulp0   var byte bank0 system
hulp1   var byte bank0 system
hulp2   var byte bank0 system
whulp   var byte bank0 system
pclhulp var byte bank0 system
sthulp  var byte bank0 system

;---Zeroing registers---
count0   = 0
count1   = 0
count2   = 0
count3   = 0  
count4   = 0
count5   = 0
hulp0    = 0
hulp1    = 0
hulp2    = 0
whulp    = 0
pclhulp  = 0
sthulp   = 0
STATUS.0 = 0

Goto main ;Skip interrupt routine

define INTHAND int

DISABLE DEBUG

asm
;---Save W, STATUS and PCLATH---
int movwf whulp
    swapf STATUS, W
    clrf STATUS
    movwf sthulp
    movf  PCLATH, W
    movwf pclhulp
    
;---Clock program---    
    incf count0, F
    movwf count0
    call check
    movf count0, W
    btfss STATUS,0
    goto eindafwerking
    incf count1, F
    movwf count1
    call check
    movf count1, W
    btfss STATUS,0
    goto eindafwerking
    incf count2, F
    movwf count2
    call check
    movf count2, W
    btfss STATUS,0
    goto eindafwerking
    incf count3, F
    movwf count3
    call check
    movf count3, W
    btfss STATUS,0
    goto eindafwerking
    incf count4, F
    movwf count4
    call check
    movf count4, W
    btfss STATUS,0
    goto eindafwerking
    incf count5, F
    movwf count5
    call check
    movf count5, W
    btfss STATUS,0
    goto eindafwerking

;---Restore W, STATUS and PCLATH---
eindafwerking movf pclhulp, W
              movwf PCLATH
              swapf sthulp, W
              movwf STATUS
              swapf whulp, F
              swapf whulp, W
              bcf intcon,2
              retfie

;---Check function for counts to be 99h maximum (NOT USED YET)---
check return
ENDASM

ENABLE DEBUG

main:
   INTCON = %10100000                  ;GIE enabled, T0IE enabled
   OPTION_REG = %00000111           
   goto loop
   
loop:   goto loop                           ;Wait here for interrupt
    The program before (with the LED) was to time it on 1 millisecond, the final program (which isn't this one ofcourse ) is for measurement purposes.

    Test step 2:
    What I try to do here is to make a counter, that increments count0 when the timer overflows, then when count0 is full, it increments count1 etc etc. Atleast... it should do that....

    The things i tried to make it work:
    - Reset the C flag of STATUS, only this made only count0 to run.
    - Switched , W with , F and vice versa (example: STATUS, W becomes STATUS, F)

    A colleague told me to make some own save location (pclhulp, whulp and sthulp). I'm not sure if this is okay...

    If someone could help me out again, I will be very gratefull (again!!).

    Cheers,

    William

    (Excuse me for the dutch labeling, it shouldn't be be much of a problem i guess )

    /EDIT:

    Allrightey I fixed the problem myself! Yay ^^!

    Code:
    define loader_used 1  
define osc 20 

;---Defining Variables---
wsave var   byte $70 system
ssave var   byte bank0 system
psave var   byte bank0 system       

count0  var byte bank0 system
count1  var byte bank0 system
count2  var byte bank0 system
count3  var byte bank0 system  
count4  var byte bank0 system
count5  var byte bank0 system
hulp0   var byte bank0 system
hulp1   var byte bank0 system
hulp2   var byte bank0 system
whulp   var byte bank0 system
pclhulp var byte bank0 system
sthulp  var byte bank0 system

;---Zeroing registers---
count0   = 0
count1   = 0
count2   = 0
count3   = 0  
count4   = 0
count5   = 0
hulp0    = 0
hulp1    = 0
hulp2    = 0
whulp    = 0
pclhulp  = 0
sthulp   = 0
STATUS.2 = 0

Goto main ;Skip interrupt routine

define INTHAND int

DISABLE DEBUG

asm
;---Save W, STATUS and PCLATH---
int movwf whulp
    swapf STATUS, W
    clrf STATUS
    movwf sthulp
    movf  PCLATH, W
    movwf pclhulp
    
;---Clock program---    
    incf count0, F
    movf count0, W
    call check
    movwf count0
    btfss STATUS,2
    goto eindafwerking
    bcf STATUS,2
    incf count1, F
    movf count1, W
    call check
    movwf count1
    btfss STATUS,2
    goto eindafwerking
    bcf STATUS,2
    incf count2, F
    movf count2, W
    call check
    movwf count2
    btfss STATUS,2
    goto eindafwerking
    bcf STATUS,2
    incf count3, F
    movf count3, W
    call check
    movwf count3
    btfss STATUS,2
    goto eindafwerking
    bcf STATUS,2
    incf count4, F
    movf count4, W
    call check
    movwf count4
    btfss STATUS,2
    goto eindafwerking
    bcf STATUS,2
    incf count5, F
    movf count5, W
    call check
    movwf count5
    bcf STATUS,2
    goto eindafwerking


;---Restore W, STATUS and PCLATH---
eindafwerking movf pclhulp, W
              movwf PCLATH
              swapf sthulp, W
              movwf STATUS
              swapf whulp, F
              swapf whulp, W
              bcf intcon,2
              retfie

;---Check function for counts to be 99h maximum (NOT USED YET)---
check return
ENDASM

ENABLE DEBUG

main:
   INTCON = %10100000                  ;GIE enabled, T0IE enabled
   OPTION_REG = %00000111           
   goto loop
   
loop:   goto loop                           ;Wait here for interrupt
    What I did wrong:
    - I switched the movf and the movwf instructions!
    - Checked the wrong bit, it checked the carry flag (Status.0) instead of the Zero flag (Status.2)

    I feel so noobish >)
    Last edited by WishMaster^; - 17th April 2007 at 10:27. Reason: Made some things more clear.. EDIT2: Fixed the problem..
  4. - 17th April 2007, 11:16 #4
    skimask's Avatar
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    Quote Originally Posted by WishMaster^ View Post
    I feel so noobish >)
    Really? Well...how many 'noob's' can say they fixed a problem on their own.
    I do believe you've done graduated out of the noob class...
    Now go let all the smoke out of a PIC to celebrate!
  5. - 19th April 2007, 10:15 #5
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    Quote Originally Posted by skimask View Post
    Really? Well...how many 'noob's' can say they fixed a problem on their own.
    I do believe you've done graduated out of the noob class...
    Now go let all the smoke out of a PIC to celebrate!
    I can count myself as a real rookie now!!

    Now that my program is growing, I encountered a new problem.
    The program is now some sort of stopwatch with 1 control button on portb.4.
    The problem is, that when I press the button, the timer won't start and it goes straight to "The time is: 00,00"

    What do I miss here?


    anyone? ^^

    Cheers,

    William

    /EDIT While I studied the behaviour of the program, I saw something odd... When i press RB4, INTCON.0 is set, BUT the interrupt enable bit is cleared on the same time. That's why it doesn't interrupt.

    Now I have forced the enable bit to stay set, only when I run it then it gives me an adress missmatch error. So that isn't the solution...

    Anyone with a clue what might reset INTCON.3?
    Attached Files Attached Files
    Last edited by WishMaster^; - 19th April 2007 at 13:02. Reason: Added a founding......
    ------------
    Oh Noes...
    ------------
  6. - 23rd April 2007, 08:29 #6
    WishMaster^'s Avatar
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    Default Odd...

    Okay, in debug mode all works fine now, but, when I compile and load the program without the debugger, then it goes bananas. What I suspect now, is that there is a signal in PortB what is resonating when I press the button. This will cause many interrupts, making the microcontroller think that I press the stop button right away.

    That will explain why it skips the interrupt routine without the debugger on...

    Before I order any parts to solve this, I want to know if I'm close or not. So is this a problem that might occure while making something like this?



    Cheers,

    William
    Attached Files Attached Files
    ------------
    Oh Noes...
    ------------
  7. - 23rd April 2007, 09:56 #7
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    Quote Originally Posted by WishMaster^
    A colleague told me to make some own save location (pclhulp, whulp and sthulp). I'm not sure if this is okay...
    I don't think I'd be listening to that guy too much.

    If you are using a chip with more than 2K of program memory,PBP automatically inserts code to do the context saving. It uses the wsave, ssave and psave variables. Why? I don't know. But it does.

    In the process of saving the context, it also changes the W and STATUS registers. So if you try to save and restore it with different variables, you're only saving the changed values. Then the real values never get restored.

    This will send PBP to the Funny Farm. Or at least the person trying to figure it out.

    So, lose the saving portion of the interrupt handler, then change the restore section to what's shown in the manual.

    HTH,
    DT
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