CPE300 Fall2011 Awesome 8051 Project: Keypad Reader

EE292 Fall2012Awesome Project:Keypad ReaderBrendan Morris

12/06/20121Abstract/Goal/Motivation/IntroductionAccept user input from a 9 digit keypadThis should be non-blocking to allow the processor to do other calculationsOutput key is illuminated on an 7-segment LED

2Description Usage: A user presses on a single keypad button and the button that is pressed gets displayed on the LED arrayKeypad numbering

Keypad is interrupt drivenMust set keypad to pulse operation and have the AND enabled interrupt button activeNumber of the pressed key is written to the 7-segment display

3ImplementationHardwareExternal Keypad7-segment LED Enable/initialize external interruptMain program waits for key pressOn key pressRun external interrupt service routine (ISR)Poll keypad to find which key was pressedOutput number of key pressed to illuminate 7-segment display

Issues/subtletiesStill have to poll keys even under interrupt (software decoding)Must be sure to enable/disable interrupts during ISR

Software design

4Results Demo

http://youtu.be/bi9vrCkJWHg5