基本的PICmicro振荡器的设计
Theoscillatorcircuitforalmostanymicrocontrollerisa
fairlysimpledesignwithveryfewcomponents.Select-
ingthevaluesforcapacitorsandresistorsfromthe
manufacturers’databookswillgetyouacircuitthat
oscillates.However,manyconditionscanadversely
affecttheperformanceofyouroscillatordesign.Higher
temperaturesandlowersupplyvoltagescanlowerthe
amplifiergain(andthustheloopgainintheoscillator
circuit)causingpoor,slow,ornostart-up.Coldertem-
peraturesandhighersupplyvoltagescanincrease
amplifiergain,causingthecircuittobeforcedtoa
higherharmonicandthrowoffthetiming.Thecrystal
canalsobeoverdrivenandbecomepotentiallydam-
agedandceasefunctioningaltogether.Itisalsopossi-
bletowastepowerthroughtheimproperselectionof
componentsorClockmodes.AN849BasicPICmicroOscillatorDesignTheOscillatorCircuitAuthor:DanMatthewsMicrochipTechnologyInc.ThecircuitshowninFigure1isatypicalparallelreso-nantoscillatorcircuit,asusedwiththeMicrochipPIC-microfamilyofdevices.TheoutputofaninvertingINTRODUCTIONamplifierisfedbacktoitsinputtocreatean"unstable"
