; somewhere inside ISR of PCA (counter overflow condition): INT_PCA_OVER: ; check if watchdog counter reset is required somewhere JNB FLG_WATCHDOG,INT_PCA_WATCHDOG_END CLR EA MOV WDTRST,#0x1E ; reset watchdog counter MOV WDTRST,#0xE1 CLR FLG_WATCHDOG ; clear request flag SETB EA INT_PCA_WATCHDOG_END: ; ...