实现的PIC18C601801无ROM微控制器的引导程序的固件

ThePIC18C601andPIC18C801microcontrollersare

thefirstmembersofMicrochip’sPIC18familywithno

on-chipprogrammemory.TheyofferthePIC18archi-

tecture,withtheabilitytousedifferenttypesandsizes

ofexternalprogrammemory(upto2Mbyte)toexactly

fitmostapplications.

Inmodernembeddedapplications,wherefeaturesand

functionalityareconstantlyevolving,FLASHmemoryis

anidealchoiceforexternalprogrammemory.Field

upgradabilityisalmostalwaysdesirableinthesesys-

tems,too.MostcommonlyavailableFLASHdevices,

however,disablereadaccesswhilebeingprogrammed

orerased.Theyalsorequirespecialcommand

sequencesforprogramming,andhavelongererase

andwritetimesthanreadtimes.Asaresult,systems

usingFLASHtechnologyrequireeitherasecondmem-

orydevice,oramicrocontrollerwithbuilt-inmemory

space,inordertoimplementfieldreprogrammability.

PIC18C601/801controllersdothisbyallowingpartof

on-chipdatamemorytobereconfiguredasprogram

memory.MAN819ImplementingBootloaderFirmwareforthePIC18C601/801ROMlessMicrocontrollersThisapplicationnotediscussesthegeneraldesignAuthors:GaurangKavaiyaandNileshRajbhartirequirementsforbootloaderfirmwareinaROMlessMicrochipTechnologyInc.controllersystem.Toillustratethekeypoints,afully-featuredreferencedesign,withaninterfacetoexternalhostsoft