Watchdog

Description

A watchdog is kind of a timer that can reset the chip when it gets stuck. This example show how to use it.

Pay attention to the following points:

• A limit for the timer exists, and depends on the ref clock you are using.

• If the watchdog timer is triggered, your chip will reset.

Warning

We don’t have support for watchdog on gvsoc. Therefore, this example can be execute on board only.

Commands

# Create a build repository
cmake -B build

# Manage options
cmake --build build --target menuconfig

# Run the example
cmake --build build --target run

Code

C

/*
 * Copyright (C) 2022 GreenWaves Technologies
 * All rights reserved.
 *
 * This software may be modified and distributed under the terms
 * of the BSD license. See the LICENSE file for details.
 */

/* WatchDog example
 *
 * Set a watchdog timer properly and use it.
 */

/* Note:
 * Timer for watchdog is based on RefClk = 24 MHz (Fast) if exist
 *                                or     = 32 kHz (Slow) else
 * When using the fast clock, it can be divided. For now,
 * the clock value is 6 MHz.
 */

#include "pmsis.h"

int main()
{
    printf("\n*****\nWhatchDog example\n*****\n");

    /* Setting the timer (in us)
     * And check if it has been set properly (== 0)
     */
    if (pi_watchdog_timer_set(250))
    {
        printf("Error when setting the watchdog timer.");
        /* It can happen if the timer value is to high.
         * Remind that regarding the clock the limit will be different.
         */
        return -1;
    }

    /* Starting the countdown
     * Executing a task, faster than the timer's limit.
     * WatchDog should not be trigger.
     */
    printf("Executing first task. No reset should append.\n");
    pi_watchdog_start();
    pi_time_wait_us(200);
    pi_watchdog_stop();
    printf("Task faster than the watchdog's timer. Done without reset.\n");

    /* In case you try to execute a task that last more than the timer,
     * the latter will be trigger and the watchdog will reset the chip.
     */

    printf("Executing a second task. No reset should append.\n");
    /* To execute a second task that have no attach to the first one (in term of execution time)
     * you have to rearm the timer. You can start it again then.
     * If you do not rearm it the counter will continue where it stopped.
     */
    pi_watchdog_timer_rearm();
    pi_watchdog_start();
    pi_time_wait_us(300);
    pi_watchdog_stop();
    printf("Task faster than the watchdog's timer. Done without reset.\n");

    return 0;
}