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Watchdog class hierarchy

You can use the Watchdog interface to set up a hardware watchdog timer that resets the system in the case of system failures or malfunctions.

Note: There is only one instance in the system. Use Watchdog::get_instance() to obtain a reference.

If you fail to refresh the watchdog periodically, it resets the system after a set period of time.

Note: The maximum amount of time you can set as the Watchdog timeout varies depending on the target hardware. You can check the maximum value by calling Watchdog::get_instance().get_max_timeout().

Watchdog class reference

Public Member Functions
bool start ()
 Start the Watchdog timer with the maximum timeout value available for the target. More...
bool start (uint32_t timeout)
 Start the Watchdog timer. More...
bool stop ()
 Stop the Watchdog timer. More...
uint32_t get_timeout () const
 Get the Watchdog timer refresh value. More...
uint32_t get_max_timeout () const
 Get the maximum Watchdog refresh value for this platform. More...
bool is_running () const
 Check if the Watchdog timer is already running. More...
void kick ()
 Refresh the Watchdog timer. More...
Static Public Member Functions
static Watchdogget_instance ()
 Get a reference to the single Watchdog instance in the system. More...

Watchdog example

This example creates a watchdog timer that expires after five seconds and that you can refresh by pushing BUTTON1 on the target board:

 * Copyright (c) 2020 Arm Limited and affiliates.
 * SPDX-License-Identifier: Apache-2.0

#include "mbed.h"

const uint32_t TIMEOUT_MS = 5000;
InterruptIn button(BUTTON1);
volatile int countdown = 9;

void trigger()
    countdown = 9;

int main()
    printf("\r\nTarget started.\r\n");

    Watchdog &watchdog = Watchdog::get_instance();

    uint32_t watchdog_timeout = watchdog.get_timeout();
    printf("Watchdog initialized to %lu ms.\r\n", watchdog_timeout);
    printf("Press BUTTON1 at least once every %lu ms to kick the "
           "watchdog and prevent system reset.\r\n", watchdog_timeout);

    while (1) {
        printf("\r%3i", countdown--);
        ThisThread::sleep_for(TIMEOUT_MS / 10);

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