External Watchdog solution in dual CPU(MPU) system

摘要

The present invention relates to an external Watchdog device using a dual CPU (MPU) system and a control method therefor, and solves the problems of a conventional internal Watchdog device and an external Watchdog device using an external Watchdog IC using a dual CPU (MPU) system. Provides a way to solve it. In an external watchdog device using a dual CPU (MPU) system, the sub-MPU without errors due to external noise or environmental factors periodically monitors the state of the main MPU and resets the main MPU in hardware when an abnormal operation is detected. I can make it. More specifically, the communication terminal of the main MPU and the communication terminal of the sub-MPU are connected to each other to perform communication periodically, and the sub-MPU can detect an abnormal operation of the main MPU based on not receiving a normal communication packet, At least one I/O pin in the I/O terminal of the sub MPU and the hardware reset pin of the main MPU are connected to each other, and when abnormal operation of the main MPU is detected, the main MPU is reset using the I/O pin of the sub MPU. I can make it In addition, the present invention provides a method of determining whether the MPU is initially booting or is connected to the JTAG for debugging or program download, and not resetting the main MPU in this case.