> Van: David Olson <dolson@PROGRESS.COM>
> Aan: PICLIST@MITVMA.MIT.EDU
> Onderwerp: Button Pressing Behavior
> Datum: zondag 9 mei 1999 3:45
>
> Friends,

Hello David,

> I've got a routine that polls a switch and turns an LED on or off. I
solved
> some of my earlier problems (subject: [OT] Newbie Toggle Woes...) by
adding
> a debouncing scheme. I'm using the Kunz (1999) method of TMR0 and
checking
> three times. Works great.
>
> However, if I hold the button down (RA1 is high), I get a flashing LED
> (RB1) - because it's toggling on and off.
<Snip>

> Also, I'm dying for a subroutine that I can pass parameters. This whole
> switch routine has to work for 4 switches. I'm thinking that if I throw
the
> switch information in a "generic" register, I'll get what I want.
>
> Any clues? Not looking for code - just looking for a nudge to "discover"
the
> best way.

Pseudo-code:

  1) Set a Loop-counter to some preset value.
  2) Poll the input-port your switch(es) are connected to.
  Mask off all port-bits that do not have a (required) switch attached.
(Your "argument" !)
  Check if the result is the same as last time.  If not,  goto 1)
  Decrement Loop-counter.  If not Zero goto 2)
      (if it is, the key is stable for {preset value} scan's !)

Resulting byte contains a One on places where a switch is connected, but
not pressed, and a Zero on all other places.

To check for a Key-press :
  call this routine and test for pressed key's (Zero-bits) in the returned
byte

To wait for Key-release :
  call this routine and repeat (calling the routine) if any key is pressed

I'm using this setup in several devices, and it works like a charm.

For your program:

  Check for a Key-Press
  if so :  Toggle the Led & wait for Key-Release
  repeat from top

Greetz,
  Rudy Wieser