LED-based debugging patterns in Embedded C - Mini Project: Build & Apply

LED-based Debugging Patterns

📖 Scenario: You are working with a microcontroller that has a single LED connected to a digital output pin. You want to use the LED to show different debugging patterns to understand the program flow without a serial monitor.

🎯 Goal: Create a simple embedded C program that uses the LED to blink in different patterns based on a configuration variable. You will set up the LED pin, define a pattern selector, implement the blinking logic for each pattern, and finally output the blinking pattern.

📋 What You'll Learn

Define a variable for the LED pin number

Define a variable called pattern to select the blinking pattern

Use a switch statement on pattern to control LED blinking

Implement three patterns: steady ON, slow blink, and fast blink

Use a function delay_ms(int ms) to create delays

Print the current pattern number to the console (simulate output)

💡 Why This Matters

🌍 Real World

Using LEDs to debug embedded systems is common when serial output is unavailable or limited.

💼 Career

Embedded developers often use LED patterns to quickly identify program states or errors during hardware testing.

1

Setup LED pin variable

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

Embedded C

int led_pin = 0;  // Your code here

Need a hint?

The LED is connected to pin 13. Use int led_pin = 13;.

2

Add pattern selector variable

Add an integer variable called pattern and set it to 2 to select the blinking pattern.

Embedded C

int led_pin = 13;
int pattern = 0;  // Your code here

Need a hint?

Set pattern to 2 to test the slow blink pattern.

3

Implement LED blinking patterns

Write a switch statement on pattern with cases 1, 2, and 3. For case 1, turn the LED ON steadily. For case 2, blink the LED slowly (turn ON, delay 1000 ms, turn OFF, delay 1000 ms). For case 3, blink the LED fast (turn ON, delay 200 ms, turn OFF, delay 200 ms). Use functions digitalWrite(led_pin, HIGH), digitalWrite(led_pin, LOW), and delay_ms(int ms).

Embedded C

int led_pin = 13;
int pattern = 2;

// Your code here

Need a hint?

Use switch (pattern) and implement each case with the correct delays and LED states.

4

Print the current pattern

Add a printf statement to print "Current pattern: " followed by the value of pattern.

Embedded C

int led_pin = 13;
int pattern = 2;

switch (pattern) {
    case 1:
        digitalWrite(led_pin, HIGH); // LED ON steadily
        break;
    case 2:
        digitalWrite(led_pin, HIGH);
        delay_ms(1000);
        digitalWrite(led_pin, LOW);
        delay_ms(1000);
        break;
    case 3:
        digitalWrite(led_pin, HIGH);
        delay_ms(200);
        digitalWrite(led_pin, LOW);
        delay_ms(200);
        break;
    default:
        digitalWrite(led_pin, LOW); // LED OFF
        break;
}

// Your code here

Need a hint?

Use printf("Current pattern: %d\n", pattern); to show the pattern number.