Why watchdog timer is needed in Embedded C - See It in Action

Why Watchdog Timer is Needed

📖 Scenario: Imagine you have a small robot that needs to keep working without stopping. Sometimes, the robot's brain (the microcontroller) can get stuck because of errors. To help the robot keep running, we use a watchdog timer.

🎯 Goal: You will write a simple embedded C program that shows how a watchdog timer can reset the system if it stops working properly.

📋 What You'll Learn

Create a variable to simulate the watchdog timer counter

Create a variable to set the maximum allowed count before reset

Write a loop that simulates the system running and the watchdog timer counting

Add a condition to reset the system if the watchdog timer reaches the maximum count

Print messages to show the system status and reset event

💡 Why This Matters

🌍 Real World

Watchdog timers are used in real embedded devices like robots, home appliances, and cars to make sure they keep working even if something goes wrong.

💼 Career

Understanding watchdog timers is important for embedded system developers to build reliable and safe devices.

1

Create watchdog timer variables

Create an integer variable called watchdog_counter and set it to 0. Also create an integer variable called max_count and set it to 5.

Embedded C

# Create variables for watchdog timer
# Your code here

Need a hint?

Use int watchdog_counter = 0; and int max_count = 5;.

2

Simulate system running with watchdog timer increment

Add a for loop that runs 7 times using int i = 0; i < 7; i++. Inside the loop, increase watchdog_counter by 1 each time.

Embedded C

int watchdog_counter = 0;
int max_count = 5;

// Add a for loop to increase watchdog_counter
# Your code here

Need a hint?

Use a for loop and increase watchdog_counter inside it.

3

Add reset condition when watchdog timer reaches max count

Inside the for loop, add an if statement that checks if watchdog_counter is equal to max_count. If true, set watchdog_counter back to 0 to simulate a system reset.

Embedded C

int watchdog_counter = 0;
int max_count = 5;

for (int i = 0; i < 7; i++) {
    watchdog_counter++;
    // Add if condition to reset watchdog_counter
    # Your code here
}

Need a hint?

Use if (watchdog_counter == max_count) and reset watchdog_counter inside.

4

Print system status and reset events

Inside the for loop, add a printf statement to print "Watchdog counter: %d\n" with watchdog_counter. Inside the if block, add a printf statement to print "System reset by watchdog timer!\n".

Embedded C

int watchdog_counter = 0;
int max_count = 5;

for (int i = 0; i < 7; i++) {
    watchdog_counter++;
    printf("Watchdog counter: %d\n", watchdog_counter);
    if (watchdog_counter == max_count) {
        printf("System reset by watchdog timer!\n");
        watchdog_counter = 0;
    }
}

Need a hint?

Use printf to show the counter and reset message inside the loop and if block.