Abstract: Acomputationmodelintegratedwithinterruptsandtaskswaspresentedfortheanalysisofworstcaseresponsetime(WCRT)foranaerospaceembeddedsystemwithmultilevelinterrupts.Bothinterruptsandtaskswasusedforaunifiedprioritydefinitioninthismodel,sothetiminganalysisofnestedinterruptscanbecombinedwithtaskresponsetimeanalysistechniques.TheWCRTofbothinterruptsandtaskswasderivedintheintegratedmodel.Furthermore,detaileddescriptionsofkeyparameterswereproposedandthedifferencesbetweeninterruptsandtaskswerealsodiscussed.TheopensourceLEON3processorplatformandModelsimsoftwarewereintroducedtosimulateandverifythemethod.TheresultsshowthattheoverestimateoftaskWCRTislessthan5%whichdemonstratestheeffectivenessofthemethodandthevalueforengineeringapplications.

Key words: realtimesystem, embeddedsoftware, multilevelinterrupt, fixedpriorityscheduling, schedulabilityanalysis, worstcaseresponsetime, spacecraft