You have failed to recognize a third state:

Timer1 is running and overflows > 50.


When the button is pressed, why not simply check if overflows is
greater than 50? If so, reset the timer, if not (i.e. overflows <=3D
50), start/stop the timer. This assumes that one doesn't care if the
timer needs to be running or not after the 50 overflows. If the
start/stop is still required after the 50, the button would need to be
pressed twice (first to stop the timer, then to reset it.)

Unless I have completely misinterpreted your situation...

-Scott



On Wed, Apr 1, 2009 at 10:38 AM, Rikard Bosnjakovic
<rikard.bosnjakovic@gmail.com> wrote:
> I'm working on a Timer1-based project where a button should serve
> three purposes: start the timer, stop the timer, reset the timer.
> Implementing the start/stop alone is easy (TMR1ON =3D 1 ^ TMR1ON), but
> I'm having serious problems figuring out how I can implement the reset
> as well.
>
> What I have been playing around with is Timer0. As soon as RA0 is
> pressed T0IE is set (cleared when RA0 is released), and the ISR counts
> overflows. Later I have made logic based on the amount of
> TMR0-overflows.
>
> This is how I want it to behave:
>
> * (If RA0 is pressed) AND (Timer1 is stopped) AND (overflows > 50) =A0=3D=
> =A0reset
> * (If RA0 is pressed) AND (either state of Timer1) AND ( 0 < overflows
> < 5) =3D> TMR1ON =3D 1 ^ TMR1ON
>
> (50 overflows is a couple of seconds - no need to be exact)
>
> I have implemented both of these but I cannot make them work together.
> Been wasting(?) two hours on this so I can't really think straight any
> longer.
>
> Does anyone have suggestions for another approach other than use Timer0?
>
>
> --
> - Rikard - http://bos.hack.org/cv/
> --
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