It sound very noisy button. I have not seen 30 ms bouncing signal
coming from a button. I assume you did not see it under a
osciloscope. My avagare bouncing lasts for less than one ms. I use
three successive stable readings to validate a keystroke within 12ms
periodic polling to read matrix key strokes and it works just fine.

Aydin

> I am planning to debounce a simple pushbutton connected to a PIC input with
> weak pullups enabled.  My strategy is to read the button every 10ms, and
> when 4 successive reads are the same, consider the level valid.  This will
> of course mean that the button level must be the same for at least 30ms to
> be considered valid.  The algorithm I am using will easily allow checking
> for up to 8 matching reads, any more than that and I'll have to change the
> method.
>
> Any comments on this?  Is 10ms about right?  How about using 4 successive
> reads, is this enough, too many, etc.?
>
>
> TIA - Martin R. Green
> elimar@bigfoot.com
>