First embedded program (LED blink) in Embedded C - Mini Project: Build & Apply

First embedded program (LED blink)

📖 Scenario: You have a small board with a single LED light. You want to make the LED blink on and off repeatedly. This is the first step to learning how to control hardware with code.

🎯 Goal: Write a simple embedded C program that turns an LED on and off with a delay, making it blink continuously.

📋 What You'll Learn

Create a variable to represent the LED pin number

Create a delay function to pause the program

Write code to turn the LED on and off in a loop

Print or indicate the LED state changes (for simulation or debugging)

💡 Why This Matters

🌍 Real World

Blinking an LED is the first step in learning how to control hardware devices like lights, motors, or sensors using code.

💼 Career

Embedded programmers often start by controlling simple hardware outputs like LEDs before moving on to complex device control.

1

Set up the LED pin variable

Create an integer variable called led_pin and set it to 13, which represents the LED pin number.

Embedded C

int led_pin = 0;
// Your code here

Need a hint?

Think of the LED pin as the address where the LED is connected. Pin 13 is common for built-in LEDs.

2

Create a delay function

Write a function called delay that takes an integer ms and uses a simple loop to create a delay approximately equal to ms milliseconds.

Embedded C

int led_pin = 13;

void delay(int ms) {
    // Your code here
}

Need a hint?

The delay function uses a loop to waste time. The volatile keyword prevents the compiler from optimizing the loop away.

3

Write the main loop to blink the LED

Write the main function that uses an infinite while loop. Inside the loop, turn the LED on by setting led_state to 1, call delay(500), then turn the LED off by setting led_state to 0, and call delay(500) again.

Embedded C

int led_pin = 13;

void delay(int ms) {
    volatile int count = 0;
    for (int i = 0; i < ms * 1000; i++) {
        count++;
    }
}

int main() {
    int led_state = 0;
    // Your code here
}

Need a hint?

The infinite loop keeps the LED blinking forever. Changing led_state simulates turning the LED on and off.

4

Print the LED state changes

Add printf statements inside the loop in main to print "LED ON" when the LED turns on and "LED OFF" when it turns off.

Embedded C

int led_pin = 13;

void delay(int ms) {
    volatile int count = 0;
    for (int i = 0; i < ms * 1000; i++) {
        count++;
    }
}

int main() {
    int led_state = 0;
    while (1) {
        led_state = 1; // LED ON
        // Your code here
        delay(500);
        led_state = 0; // LED OFF
        // Your code here
        delay(500);
    }
    return 0;
}

Need a hint?

Use printf("LED ON\n") and printf("LED OFF\n") to show the LED state changes.