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By: Clive Wakeham, created: 2011-03-22 | updated: 2013-06-17
Updated version of my 74C922 4x4 keypad chip driver and buffer.
This version works with the 74C922 and the 74C923.
This version has the following methods; start, stop, read last key, read the size of the buffer, clear the buffer, and search the buffer for a specific key value.
Added a feedback function to drive an LED or buzzer (via transistor etc).
Datasheet for the 74C922/74C923 is included.