Self-monitoring system for detecting error at output port during cold start of microprocessor system

摘要

A self-monitor system for a microprocessor performs self-checking during cold-start of the microprocessor. Self-checking is performed by applying a dummy load to a specific output port, and detecting the signal level at a checking port connected to the specific output port so that the output level at the check port coincides with the dummy load applied to the specific output port within a predetermined allowable time lag. An alarm is produced and a fail-safe operation is carried out if the signal level at the check port coincident with the dummy load is not detected within a given period of time after the allowable time lag.