Interrupt-driven keyboard for MCS-51


Posted on Sep 17, 2012

Designers of microcontroller-based products that require a keypad for user data entry can select from dedicating an input line for each key, continuously polling the keypad`s x and y lines, or generating an interrupt whenever a user presses a key. Although conceptually simple, dedicating lines to a keypad can tie up most of the microcontroller`s I/O resources. Continuously polled keypads can burden the microprocessor`s resources and consume excessive amounts of battery power.



The third method, an interrupt-driven keypad, offers several benefits. First, using interrupts frees the microcontroller to perform other tasks or to switch into an idling or power-down mode while awaiting the next key closure. Second, using interrupts he




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