远程通信的实施

Thisapplicationnotediscusseshowtoimplement“long

calls”inthePIC16C5Xarchitecture.Theuseoflongcall

cansimplifythepartitioningoftheapplicationprogram

withminimalsoftwareoverhead.

InthePIC16C5Xarchitecture,theprogrammemory

pagesizeis512words.Dependingonthedevice,the

programmemorymaybeaslargeas2Kwords(asin

thePIC16C57orPIC16C58devices).Theprogram

counter(andstack)widthrangefrom9-to11-bits,

dependingontheamountofprogrammemory.Table1

showsthewidthoftheProgramCounter(PC)and

Stackforthevariousdevices.

Theloworder8-bitsoftheprogramcounterare

accessiblebytheuserprogram.Thesebitsare

containedinthePCregister.AN581ImplementingLongCallsFigure1showsthestructureofthePC.SinceA8isAuthor:MarkPalmerforcedto0byCALLinstructions,thestartaddressofMicrochipTechnologyInc.subroutinesmustbeintherst256wordsofeachpro-grammemorypage.Dependingonthesizeandnum-berofcalledsubroutines,thislimitationmaybecomeaINTRODUCTION