PIC 使用一个定时器控制led和按键

Thepurposeofthisapplicationnoteistodesignaclock

whilemultiplexingthefeaturesasmuchaspossible,

allowingthecircuittousethe18-pinPIC16C54.Other

devicesintheMicrochiplineexpandonthispart,mak-

ingitagoodstartingpointforlearningthebasics.This

designisusefulbecauseitutilizeseverypinforoutput

andswitchessomeofthemtoinputsbrieflytoreadthe

keys.Foramoreextensiveclockdesign,consultappli-

cationnoteAN529.AN590AClockDesignUsingthePIC16C54forLEDDisplaysandSwitchInputsOPERATIONAuthor:DanMatthewsMicrochipTechnologyInc.SwitchesWhennobuttonsarepressed,thecircuitwilldisplaytheINTRODUCTIONcurrenttime,startingat12:00onreset.PressingSW1Thepurposeofthisapplicationnoteistodesignaclockwillcausesecondstobedisplayed.Thetimeissetbywhilemultiplexingthefeaturesasmuchaspossible,pressingSW2toadvanceminutes,andSW3toallowing