PWM输出频率和分辨率选择

ThePIC17C42isequippedwithtwohighfrequency

PulseWidthModulation(PWM)outputs.Inapulse

widthmodulatedsignaltheperiodofthesignalis

(usually)keptfixed,whilethedutycycleisvaried.Inthis

applicationnote,wewilldiscussoptionsinselecting

PWMfrequencyandresolution.

Thisapplicationnoteassumesthattheinternalclockis

usedforthetime-base,whichistypicallythepreferred

setup.Also,throughoutthisapplicationnote,PWM1

outputisusedinexamples,Timer1isassumedtobe

thetime-base.AN539FrequencyandResolutionOptionsforPWMOutputs(PR1=18h),thenPWMfrequencyis:Authors:StanD’SouzaandSumitMitra1/(100x62.5)ns=160kHz.MicrochipTechnologyInc.NotehoweverthatthedutycycleresolutionisalittleINTRODUCTIONlessthan7-bits.UsefulandCommonPWMModesThePIC17C42isequippedwithtwohighfrequencyPulseWidthModu