Timer interrupt for periodic tasks in Embedded C - Mini Project: Build & Apply

Timer interrupt for periodic tasks

📖 Scenario: You are programming a simple embedded system that needs to perform a task repeatedly every second. To do this efficiently, you will use a timer interrupt that triggers periodically.

🎯 Goal: Build a program that sets up a timer interrupt to toggle an LED every second using a timer interrupt handler.

📋 What You'll Learn

Create a variable to count timer ticks

Configure a timer with a 1-second period

Write an interrupt service routine (ISR) to toggle an LED

Print the LED state in the main loop

💡 Why This Matters

🌍 Real World

Timer interrupts are used in embedded systems to perform tasks regularly without wasting CPU power.

💼 Career

Understanding timer interrupts is essential for embedded software developers working on microcontrollers and real-time systems.

1

Create a variable to count timer ticks

Create a global variable called timer_ticks and initialize it to 0.

Embedded C

# Your code here

Need a hint?

Use the volatile keyword because this variable will be changed inside an interrupt.

2

Configure a timer with a 1-second period

Write a function called setup_timer() that configures a hardware timer to generate an interrupt every 1 second. Inside the function, set the timer period to 1000 milliseconds and enable the timer interrupt.

Embedded C

volatile int timer_ticks = 0;

// Your code here

Need a hint?

Use your microcontroller's timer registers to set the period and enable interrupts.

3

Write an interrupt service routine (ISR) to toggle an LED

Write an ISR function called timer_ISR() that increments timer_ticks by 1 and toggles a variable led_state between 0 and 1 each time it is called.

Embedded C

volatile int timer_ticks = 0;

void setup_timer() {
    // Pseudocode for timer setup
    // Set timer period to 1000 ms
    // Enable timer interrupt
    // Start timer
}

int led_state = 0;

// Your code here

Need a hint?

The ISR should update the tick count and flip the LED state.

4

Print the LED state in the main loop

In the main() function, call setup_timer() once, then create an infinite loop that prints LED ON when led_state is 1 and LED OFF when led_state is 0.

Embedded C

volatile int timer_ticks = 0;

void setup_timer() {
    // Pseudocode for timer setup
    // Set timer period to 1000 ms
    // Enable timer interrupt
    // Start timer
}

int led_state = 0;

void timer_ISR() {
    timer_ticks++;
    led_state = !led_state;
}

int main() {
    setup_timer();
    // Your code here
}

Need a hint?

Use a loop to continuously print the LED state based on led_state.