Watchdog timer operation in Embedded C - Mini Project: Build & Apply

Watchdog Timer Operation

📖 Scenario: You are working on a simple embedded system that needs to stay responsive. To avoid the system freezing, you will use a watchdog timer. The watchdog timer resets the system if it is not refreshed regularly.

🎯 Goal: You will write a small program that sets up a watchdog timer, refreshes it in a loop, and prints a message when the watchdog is refreshed.

📋 What You'll Learn

Create a variable to represent the watchdog timer control register

Create a variable for the watchdog timer refresh value

Write a function to refresh the watchdog timer

Use a loop to refresh the watchdog timer multiple times

Print a message each time the watchdog timer is refreshed

💡 Why This Matters

🌍 Real World

Watchdog timers are used in embedded systems like home appliances, cars, and medical devices to ensure the system recovers from unexpected freezes.

💼 Career

Understanding watchdog timer operation is important for embedded software engineers to write reliable and safe firmware.

1

Setup Watchdog Timer Control Register

Create an unsigned int variable called WDT_CTRL and set it to 0x00 to represent the watchdog timer control register.

Embedded C

# Create an unsigned int variable called WDT_CTRL and set it to 0x00
# Your code here

Need a hint?

The watchdog timer control register is usually a hardware register. Here, we simulate it with a variable.

2

Define Watchdog Refresh Value

Create an unsigned int variable called WDT_REFRESH_VALUE and set it to 0xAA. This value will be used to refresh the watchdog timer.

Embedded C

unsigned int WDT_CTRL = 0x00;
# Create an unsigned int variable called WDT_REFRESH_VALUE and set it to 0xAA
# Your code here

Need a hint?

The refresh value is a special code that resets the watchdog timer counter.

3

Write Watchdog Refresh Function

Write a function called refresh_watchdog that takes no parameters and sets WDT_CTRL to WDT_REFRESH_VALUE.

Embedded C

unsigned int WDT_CTRL = 0x00;
unsigned int WDT_REFRESH_VALUE = 0xAA;

// Write a function called refresh_watchdog that sets WDT_CTRL to WDT_REFRESH_VALUE
// Your code here

Need a hint?

This function simulates the action of refreshing the watchdog timer by writing the refresh value to the control register.

4

Refresh Watchdog in a Loop and Print

Write a main function that calls refresh_watchdog() five times in a for loop. After each call, print "Watchdog refreshed" followed by a newline.

Embedded C

unsigned int WDT_CTRL = 0x00;
unsigned int WDT_REFRESH_VALUE = 0xAA;

void refresh_watchdog() {
    WDT_CTRL = WDT_REFRESH_VALUE;
}

// Write main function to refresh watchdog 5 times and print message each time
// Your code here

Need a hint?

The main function runs the refresh five times and prints the message each time.