Hi Heinz,

my knowledge here is limited to beginner hobbyist so treat my comments
accordingly.

My experience has been I can disable tmr0 and use timer1.

I am curious why you clear the int flag if you dont want to use it.

; Setup for TMR0 and enable interrupts
;
;    clrf    TMR0        ; start timer known state
;
    bcf     INTCON,T0IF ; clear TMR0 interrupt flag
;

Cheers Justin


2009/7/11 Heinz Czychun <hczychun@lks.net>

> Hi,
>    I'm having a little problem with controlling Timer 0 and Timer 1
> interrupts separately, on a PIC12F675.
>
>    With Timer 1 disabled I'm able to control Timer 0 effectively with the
> INTCON,T0IE bit. Off and on. But when I enable Timer 1, Timer 0 also starts
> up and starts interrupting the processor.
>
>    Is this normal? Is it a known problem? Or am I missing something?
>
>    While it's not a big deal, it can be handled in the isr. But it's a
> headache to trouble shoot and quite disconcerting when you expect only one
> timer to be in operation, and another that should be off, is generating
> interrupts. I'd like TMR1 to be on, and not have TMR0 interrupting thr
> processor
>
> These are my settings
>
> ; initialize interrupts
>      banksel  INTCON      ; Bank 0
>        movlw  b'10100000'
>        ;             1-------  (GIE)1=interrupts enabled
>        ;             -0------  (PEIE)1=enable peripheral interrupts
>        ;             --1-----  (T0IE)0=disable TMR0 overflow interrupt
>  <- controls TMR0 effectively
>        ;             ---0----  (INTE)0=disable GP2/INT external interrupt
>        ;             ----0---  (GPIE)0=disable GPIO port change interrupt
>        ;             -----0--  (T0IF)0=no on TMR0 overflow
>        ;             ------0-  (INTF)0=no GP2/INT external interrupt
>        ;            -------0   (GPIF)0=no GPIO port change
>        movwf  INTCON
>
> but when
>
> ; enable peripheral interrupts
>      banksel  PIE1        ; Bank 1
>        movlw  b'00000001'
>        ;             0-------   0=disable EE write complete interrupt
>        ;             -0------   0=disable A/D converter interrupt
>        ;             --xx----   not implemented
>        ;             ----0---   0=comparator interrupt disabled
>        ;             -----xx-   not implemented
>        ;             -------1   (TMR1IE)1=enable TMR1 overflow interrupt
>        ;                          strangely this seems to also turns on
> timer 0
>        movwf  PIE1
>
> ; initialize TMR1
>      banksel  T1CON       ; Bank 0
>        movlw  b'00000101'
>        ;             x-------    not implemented
>        ;             -0------    0=gate disabled
>        ;             --00----   11=1:8 prescaler,
>        ;                           10 = 1:4,01 = 1:2,00 = 1:1
>        ;              ----0---   (T1OSCEN)0=LP oscillator is off
>        ;              -----1--   (T1SYNC) 1=external clock input not
> synchronized
>        ;              ------0-   (TMR1CS) 0=internal clock
>        ;              -------1   (TMR1ON) 1=timer1 enabled
>        movwf  T1CON
>
> ; initialize interrupts
>      banksel  INTCON      ; Bank 0
>        movlw  b'01000000'
>        ;             0-------  (GIE)1=interrupts enabled
>        ;             -1------  (PEIE)1=enable peripheral interrupts
>        ;             --0-----  (T0IE)0=disable TMR0 overflow interrupt
>  <-- TMR0 runs irespective of this
>        ;             ---0----  (INTE)0=disable GP2/INT external interrupt
>      bit setting
>        ;             ----0---  (GPIE)0=disable GPIO port change interrupt
>        ;             -----0--  (T0IF)0=no on TMR0 overflow
>        ;             ------0-  (INTF)0=no GP2/INT external interrupt
>        ;             -------0  (GPIF)0=no GPIO port change
>        movwf  INTCON
>
> ;
> ; Clear TMR0, its Flag and enable interrupts
> ;
>    clrf  TMR0               ; start timer known state
> ;
>     bcf  INTCON,T0IF        ; clear TMR0 interrupt flag
>     bsf  INTCON,GIE         ; enable global interrupts
>
>    complete code attached.
>
>    T0IE becomes effective again if any of the TMR1 control bits are cleared
> to stopping TMR1.
>
>    I have some PIC12F683s coming so I can see if I have the same trouble
> with them.
>
> Thanks,
> Heinz Czychun
>
>
>
>
>
>
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