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Fig 2.5
Normal computer keyboards suffer from the same problem. If I press any pair of keys (e.g.
'w' and 'n') then it will choose to display both and repeat one of them. However, if I press
(e.g 'e', 'd' and 'u') on my laptop simultaneously then the laptop recognizes that there could
be a ghost key and types nothing at all.
2.2.3 Debouncing the Keypad
In a simple circuit with a switch and a light-bulb, we press the switch, the light comes on
and we think that it's as simple as that. But to electronic circuits that operate at anything
above a few hundred Hz, a keypress appears to bounce several times before settling
down, as though you'd pressed it many times very quickly [Fig 2.6].
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