"Paul B. Webster VK2BZC" wrote:

>   Four switches eh?  OK, match them with four bits in a register which
> we call "previous", and a 4-bit variable called "count".  It should be
> fairly obvious that one byte can be used for both.
> 
>   Depending on how you wish your timing loop to perform, you may at this
> point proceed to your "other" task for a further 2 ms, or loop back and
> find any other switch that does not match "previous".  In either case,
> if there was only one switch changed (and most of the time, there will
> only be one), the next iteration finds the switches match "previous",
> and "count" is reset to $F.
> 
>   Is this clear enough?

Very. A nice variation would be to sample slightly slower, to 
check the counter before you reset it to $F, and also check if 
"new" is the default state. Now you can react differently to "long" 
keypresses than "short" ones.

-- 
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