| Previous by date: | 3 Sep 2008 12:56:27 -0000 Re: [gnupic] about data tables and shared variables, Robert Pearce |
| Next by date: | 3 Sep 2008 12:56:27 -0000 Re: [gnupic] problems with timer0/interrupts, George M. Gallant |
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Hi guys,
Thanks so much Robert, first of all. Both your code about table reads worked out of the box, and were also right about my missunderstanding of the variables' thing.
I didn't think of trying to declare it as global and then try to use it in other modules.
I'm having a problem now with interrupts/timer0.
As petter suggested, I've started scanning 3 seven segment displays on my app's main function, while using interrupts to update a counter upon a switch's press/debounce.
Then, what did was to setup interrupts for RB4:7 pins' state change, and within it's processing function, try to use timer0 to debounce the switch.
However, when I program the device and place it on it's side of the breadboard, it seems the pic falls into the interrupt, and that the timer0 polling causes it to recurse into it undefinetely.
I'm gonna paste the relevant part of the code for if anyone want to give me some explanation.
this is my main file:
;;
;; variables
;;
main_vars udata
;; main counter
counter res 1
;; temp variables
digit res 1
aux res 1
;;
;; imported symbols
;;
extern hp_interrupt
;; a table read function, with a `movwf segments_port'
;; at the end of it
extern display
;;
;; exported symbols
;;
global counter
global digit
;;
;; reset vector
;;
reset_vector code 0x0
goto main
;;
;; high-priority interrupt vector
;;
_hp_interrupt code 0x8
goto hp_interrupt
;;
;; app's entry point
;;
main:
;;
;; ports' setup
;;
;; porta
clrf porta
clrf trisa
;; portb, here I'm supossed to have a switch which is
;; active-low, thus, when pressed goes low, and this
;; ports' setup seems to be giving me problems also
clrf latb
movlw 0xff
movwf trisb
;; portc
clrf latc
clrf trisc
;; portd
clrf latd
clrf trisd
;; porte
clrf late
clrf trise
;;
;; interrupts
;;
;; enable rb pins change interrupt, and it's pullups
bsf intcon, rbie
bcf intcon2, rbpu
;; clear it's flag bit
bcf intcon, rbif
;; disable tmr0 interrupt
bcf intcon, tmr0ie
;; setup timer0: internal clock, 8 bits, prescale 1:64
movlw b'01000101'
movwf t0con
;; globally enable interrupts
bsf intcon, gie
start:
;; just loop, I acutally have code here for decomposing
;; `counter' so I can display it on the segment leds
;; (leading 0's not being displayed)
goto start
and this is my `interrupts.s' file:
;;
;; variables
;;
int_vars udata
;; these for high-priority interrupts
hp_w res 1
hp_bsr res 1
hp_status res 1
;;
;; imported symbols
;;
extern counter
;;
;; exported symbols
;;
global hp_interrupt
;;
;; rb* interrupt-handler
;;
_handle_rb_interrupt code
handle_rb_interrupt:
;; clear it's flag bit
bcf intcon, rbif
;; clear tmr0 and it's flag bit within `intcon',
;; and turn it on
clrf tmr0l
bcf intcon, tmr0if
bsf t0con, tmr0on
loop:
;; check for the flag bit being set as a result of an
;; overflow on the timer
btfss intcon, tmr0if
goto loop
;; then increment `counter' (should wait and debounce
;; the switch's release also)
banksel counter
incf counter, f
;; toggle on a led used as feedback @ rc0
btg latc, rc0
;; turn off the timer
bcf t0con, tmr0on
;; and return
retlw 0
;;
;; high-priority interrupt vector
;;
__hp_interrupt code
hp_interrupt:
;; save registers' status. I don't know if I'd be using
;; also low priorities, so better to go this way just in
;; case (datasheet says `retfie fast' could be
;; unreliable if so)
movwf hp_w
movff bsr, hp_bsr
movff status, hp_status
;; if the interrupt was caused by a change on rb4:7, go
;; to it's processing function
btfsc intcon, rbif
call handle_rb_interrupt
exit_hp_interrupt:
movff hp_bsr, bsr
movf hp_w, w
movff hp_status, status
retfie 0x0
end
I tried with another led on ra0 and a `btfsc intcon, tmr0if btg lata, ra0' above, so what is happening that tmr0 is causing the chip to vector to 0x8 even when I explictly disabled it.
Shouldn't be `tmr0if' just set, and not cause the chip to vector?
Regards,
| Previous by date: | 3 Sep 2008 12:56:27 -0000 Re: [gnupic] about data tables and shared variables, Robert Pearce |
| Next by date: | 3 Sep 2008 12:56:27 -0000 Re: [gnupic] problems with timer0/interrupts, George M. Gallant |
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