If the CPU fails, the control progr

If the CPU fails, the control program cannot run normally and the CPU is in an abnormal working state. For the possible failure of the program running inside the CPU, the internal WATCH DOG is used to monitor the program. Once the program runs away, the CPU will restart and re-initialize itself and its external circuits after the WATCH DOG timing time expires. Due to the CPU failure caused by the unstable voltage, IMP811 is used to set up a voltage monitoring circuit. When the CPU voltage is lower than 1.1V, an unshielded interrupt is generated to store the fault code. External interrupts are divided into non-maskable interrupts and maskable interrupts. When a maskable interrupt generates an interrupt request, the CPU's IF = O (interrupt is disabled), then the CPU will not respond to this type of interrupt. Unmasked interrupts are not restricted by the worker F, no matter what the IF is, the CPU must respond.