A circuit arrangement for supporting and monitoring a microcontroller, which is constructed externally of the microcontroller, comprises a watchdog circuit for monitoring the microcontroller, which circuit outputs an error signal if not reset by the microcontroller within a watchdog period, and an interrupt circuit, which feeds important system messages to the microcontroller as interrupt events for processing. In order correctly to combine interrupt processing and watchdog operation, the watchdog circuit is connected to the interrupt circuit and cooperates therewith in such a way that the interrupt circuit feeds at most a predetermined number of interrupt events to the microcontroller within a watchdog period.