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What is the use of a watchdog timer?
A watchdog timer (WDT) is a timer that monitors microcontroller (MCU) programs to see if they are out of control or have stopped operating. It acts as a “watchdog” watching over MCU operation. A microcontroller (MCU) is a compact processor for controlling electronic devices.
What is watchdog output?
Glossary Term: Watchdog-Output Definition. A feature of a microprocessor supervisory circuit that monitors software execution in a microprocessor or microcontroller. It takes appropriate action (assert a reset or nonmaskable interrupt) if the processor gets stuck in an infinite execution loop.
Why do we need watchdog?
A watchdog timer (sometimes called a computer operating properly or COP timer, or simply a watchdog) is an electronic or software timer that is used to detect and recover from computer malfunctions. During normal operation, the computer regularly restarts the watchdog timer to prevent it from elapsing, or “timing out”.
Is watchdog timer necessary?
Watchdog timers provide a method for alerting a system or resetting a processor whose software has experienced a freeze or hang. This functionality is especially necessary in embedded or remote systems where manually resetting the system isn’t practical or even possible.
How does the watchdog timer work in window mode?
The window mode enables more accurate detection of faults than the Time-out mode. In window mode, the watchdog timer determines that the MCU is malfunctioning and outputs a reset signal if it does not receive a signal, or receives multiple signals (= double pulse) from the MCU within the set interval.
What does a pulse on a watchdog timer mean?
The processor periodically sends a pulse to the watchdog timer to indicate that the system software is operating properly. If the watchdog timer does not receive this pulse within an allotted time frame (known as the watchdog timeout), the watchdog timer asserts a reset output.
How does the watchdog timer in E2E work?
Simply put, a watchdog timer is a device that asserts a reset output if it has not received a periodic pulse signal from a processor within a specific time frame. One way this is implemented is by a digital signal output (GPIO) from the processor feeding into the watchdog input (WDI) of an external watchdog timer as shown in Figure 1.
How does a watchdog timer work on a MCU?
In this mode, the watchdog timer determines the MCU is malfunctioning and outputs a reset signal if it does not receive a signal from the MCU within the set interval. The time-out mode is a major WDT monitoring mode or method, but it sometimes fails to detect MCU faults.