Watchdog reset recovery in Embedded C - Mini Project: Build & Apply

Watchdog Reset Recovery

📖 Scenario: You are working on a small embedded system that uses a watchdog timer to reset the device if it gets stuck. Your task is to write code that detects if the last reset was caused by the watchdog and then recovers gracefully by clearing the reset flag.

🎯 Goal: Build a simple embedded C program that checks if the last reset was caused by the watchdog timer, clears the watchdog reset flag, and then prints a message indicating the reset cause.

📋 What You'll Learn

Create a variable reset_flags to simulate the reset status register with the watchdog reset bit set.

Create a constant WATCHDOG_RESET_BIT representing the watchdog reset flag bit mask.

Write code to check if the watchdog reset bit is set in reset_flags and clear it.

Print "Watchdog reset detected and cleared." if the watchdog reset was detected.

💡 Why This Matters

🌍 Real World

Embedded systems often use watchdog timers to reset devices stuck in bad states. Detecting and recovering from these resets helps maintain system reliability.

💼 Career

Understanding watchdog reset recovery is essential for embedded firmware developers working on reliable hardware devices like IoT gadgets, automotive controllers, and industrial machines.

1

DATA SETUP: Create reset flags variable

Create an unsigned integer variable called reset_flags and set it to 0x04 to simulate the watchdog reset flag being set.

Embedded C

# Create an unsigned int variable reset_flags and set it to 0x04
# Your code here

Need a hint?

The value 0x04 means the third bit is set, which we will use as the watchdog reset flag.

2

CONFIGURATION: Define watchdog reset bit mask

Define a constant unsigned integer called WATCHDOG_RESET_BIT and set it to 0x04 to represent the watchdog reset flag bit mask.

Embedded C

unsigned int reset_flags = 0x04;
// Define WATCHDOG_RESET_BIT as 0x04
# Your code here

Need a hint?

This constant helps us check and clear the watchdog reset bit easily.

3

CORE LOGIC: Check and clear watchdog reset flag

Write an if statement that checks if reset_flags has the WATCHDOG_RESET_BIT set. If yes, clear the watchdog reset bit from reset_flags using bitwise AND with the inverse of WATCHDOG_RESET_BIT.

Embedded C

unsigned int reset_flags = 0x04;
const unsigned int WATCHDOG_RESET_BIT = 0x04;
// Check if watchdog reset bit is set and clear it
# Your code here

Need a hint?

Use bitwise AND & to check the bit and bitwise NOT ~ with AND &= to clear it.

4

OUTPUT: Print watchdog reset detection message

Add a printf statement inside the if block to print "Watchdog reset detected and cleared.".

Embedded C

unsigned int reset_flags = 0x04;
const unsigned int WATCHDOG_RESET_BIT = 0x04;

if (reset_flags & WATCHDOG_RESET_BIT) {
    reset_flags &= ~WATCHDOG_RESET_BIT;
    // Print message here
# Your code here
}

Need a hint?

Use printf("Watchdog reset detected and cleared.\n"); inside the if block.