Watchdog circuit

Abstract

The invention discloses a watchdog circuit, which comprises a watchdog chip (U6). A dog feed output end (WDO) of the watchdog chip is fed back to a manual resetting end (MR), a voltage monitoring output end (PFO) is fed back to a voltage monitoring input end (PFI), a control circuit (100) is arranged between a CPU and the watchdog chip (U6) and comprises a dog feed signal interval control module (110), the input end of the control circuit is connected with an I / O port of the CPU, and the output end of the control circuit is connected with the voltage monitoring input end (PFI) of the watchdog chip (U6); when CPU dog feed signals exceed a preset timing interval, the dog feed signal interval control module (110) outputs a control pulse, and the control pulse is led to the manual resetting end (MR) of the watchdog chip (U6) so that the watchdog chip (U6) performs resetting operation. Because the time interval of the dog feed signals can be adjusted, the watchdog circuit can be flexibly configured.

Description

technical field [0001] The invention relates to the field of electronic equipment, in particular to a watchdog circuit for monitoring and resetting a central processing unit (Central Processing Unit, CPU). Background technique [0002] Watchdogs are usually used in the fields of computers, communications, automation, etc., to ensure that the CPU program of electronic equipment can automatically reset and return to normal when the CPU program crashes. Its basic working principle is that after the CPU program crashes, the CPU will not periodically clear the watchdog circuit (commonly known as feeding the dog), and the watchdog circuit will reset the electronic equipment after a certain period of time. [0003] Such as figure 1 As shown, the watchdog circuit uses a dedicated watchdog chip, such as SP706, which mainly includes manual reset (Manual Reset, MR), feed dog input (Watchdog Input, WDI), feed dog output (Watchdog Output, WDO) and reset output (Reset, RST). The intern...

AI Technical Summary

Problems solved by technology

[0004] The disadvantage of the above-mentioned watchdog circuit is that the time period of the timer of the watchdog chip is fixed, and it is necessary to ensure that the feeding signal is less than the time period

That is to say, the priority of feeding the dog must be very high, otherwise, the CPU will be occupied by other tasks and stop feeding the dog, resulting in an abnormal restart of the system

[0005] However, various electronic devices in real life are very different. Some occasions require a longer feeding time, while others require a shorter feeding time. However, the general-purpose watchdog chip cannot meet these requirements because of its fixed time period.

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