Electronic control device with watchdog timer and processing unit to diagnose malfunction of watchdog timer

Abstract

An electronic control device includes: a processing unit that performs a predetermined process in accordance with a program; a watchdog timer that includes a time counter reset by a pulse signal output at a given period from the processing unit and outputs a signal having levels inverted depending on whether an overflow occurs; and a latch circuit that latches the signal output from the watchdog timer and outputs a signal obtained through the latching as a first output enable signal. The processing unit stops the output of the pulse signal, when diagnosing a malfunction of the watchdog timer, and diagnoses the malfunction of the watchdog timer based on the first output enable signal output from the latch circuit, after stopping the output of the pulse signal.