Abnormal forced resetting type watchdog circuit of microcontroller

Abstract

The invention discloses an abnormal forced resetting type watchdog circuit of a microcontroller. The watchdog circuit comprises a first CD4017 counter module, a second CD4017 counter module, a 555 oscillator circuit module and a level conversion circuit module. The abnormal forced returning type watchdog circuit can overcome the shortages of simple feeding condition and easy error feeding of the common watchdog; the pulse cycle can be independently adjusted to achieve long-time power-off forced resetting function; the circuit is a practical and an effective MCU monitoring circuit; the phenomena of program runaway and dead locking can be effectively solved.

Description

technical field [0001] The invention relates to a reset when the software of a microcontroller (MCU) runs away in an embedded system and a forced reset circuit in the case of hardware deadlock. Background technique [0002] In the embedded system, the microcontroller (MCU) often crashes or the program runs away due to external interference or other reasons, resulting in the product not working properly. The industry uses watchdog technology to solve this problem, and resets the system that crashes or runs away through the watchdog and makes it work normally. Watchdogs are divided into microcontroller internal watchdogs and external watchdogs. The internal watchdog is implemented by utilizing the internal resources of the MCU, including an internal dedicated watchdog or using an internal timer to realize the watchdog function. After the watchdog function is turned on, the MCU needs to re-assign the initial value or clear the timer regularly (feed the dog) through the softw...

AI Technical Summary

Problems solved by technology

If it is consistent with the active level of the external watchdog feeding dog pin, it will cause the external watchdog to fail

[0007] 3. The feeding condition of the external watchdog is simple, generally the change of the high and low levels is enough. When the system is disturbed or the MCU software is abnormal, it is easy to generate the feeding condition by mistake, so that the external watchdog cannot work normally.

[0009] 5. The external watchdog is used in conjunction with the MCU reset pin, and the effective time of the reset level is relatively short, generally at the millisecond level, which is not suitable for power-off reset

The system contains large capacitors, and a millisecond-level power failure cannot effectively consume the stored power, so power-off reset cannot be realized

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