dpharris@telus.net wrote:
>> What is the 'bounce' time for contacts on a membrane keypad (without 
>> clicky
>> discs) or the rubber keypads with carbon 'pills'. Very variable and user
>> dependent I imagine.
>
> I don't know, and I suspect, as you do, they are very variable.  However, 
> one
> still needs to wait for whatever bouncing is occurring to end; whether the
> method used employs a busy-wait, a timed interrupt, or the method that I
> outlined.  The first busy-wait wastes the cpu cycles during it, the 
> interrupt
> method is uses up resources.  The last would appear to be sufficient, and 
> it is
> likely that it fits nicely into the (pre-existing) background loop found 
> in many
> programs that implement a UI.

Ganssle describes a method where you shift in a '1' or a '0' into a byte (or 
an int16, etc) and then compare the result with 0x00 or 0xFF. You can 
enhance it further by checking the timer before shifting a bit in, to ensure 
you don't sample too fast.

Vitaliy 

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