Patent ID: 7450031

Claim:
A method of low-power scanning operation in a keyboard, comprising: providing a keypad with a plurality of keys, the keypad having a first set of terminals and a second set of terminals, wherein when a key is depressed, one of the terminals in the first set of terminals is electrically shorted to one of the terminals in the second set of terminals; providing a micro-controller including output pins and input pins; connecting the first set of terminals to the output pins of the micro-controller, and connecting the second set of terminals to the input pins of the micro-controller; connecting a pull-up resistor between a power supply and each of the second set of terminals; applying a first voltage to the output pins successively; sensing the input pins successively to detect if a short circuit is formed corresponding to one of the keys being depressed; and upon detecting a selected key is depressed, applying a second voltage momentarily at the output pin corresponding to the depressed key.