> At 02:44 AM 7/11/2009, Heinz Czychun wrote:
> >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.
> =

> I see a couple of things worth looking at:
> =

>          movlw  b'10100000'
> >         ;             1-------  (GIE)1=3Dinterrupts enabled
> >         ;             -0------  (PEIE)1=3Denable peripheral interrupts
> >         ;             --1-----  (T0IE)0=3Ddisable TMR0 overflow
> =

> 1) You say in the line above that "0 disables TMR0 overflow" but you =

> are setting to be a "1".  Check to make sure that it really is a "0".
> =

> 2) Do NOT check T0IF within your Interrupt Service Routine if you =

> aren't using it!  Here's why: T0IF will ALWAYS become set each and =

> every time TMR0 rolls over from 0xFF to 0x00.  However, if T0IE isn't =

> set, it won't cause an interrupt.
> =

> If you check T0IF, you will most likely find that it is =

> set.  However, that's NOT what caused the interrupt if T0IE has not =

> been enabled (=3D1).
> =

> Hope this helps!
> =

> dwayne
> =


On a similar problem I just couldn't figure out why all of a sudden SLEEP w=
oke =

up at once when it was supposed to be woken up by the WDT after about 18ms.=
 It =

turned out to be that I had enabled timer0 to make interrupts (TOIE=3D1 GIE=
=3D1) =

and I just cleared GIE when done before going to sleep thinking that since =

timer0 isn't running while at sleep anyway I didn't need to care about TOIE=
. =

However, timer0 did roll over after I cleared GIE but before going into sle=
ep. =

This didn't generate an interrupt but since the TOIF flag got set, sleep ex=
ited =

at once. =


This was clearly explained in figure 9-10 in the datasheet. =


/Ruben

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D

-- =

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