Blinking an LED

Build your first complete hardware project by making an LED blink using the Raspberry Pi Pico and C.

It’s time to bring everything together!
In this lesson, you’ll build your first real hardware project: a blinking LED using the Raspberry Pi Pico and C.

This is the “Hello World” of embedded programming — and it’s just the beginning.

What You’ll Build

You’ll connect an LED to a GPIO pin and write a C program that blinks it on and off every second.

What You’ll Need

• Raspberry Pi Pico (or Pico W)
• Breadboard (optional)
• 1x LED
• 1x 330Ω resistor
• Jumper wires

Wiring the Circuit

1. GPIO 15 → long leg of LED (anode)
2. Short leg (cathode) → 330Ω resistor → GND

\[Pico GPIO 15] ---\[LED]---\[330Ω]---\[GND]

How It Works

Your program will:

• Set GPIO 15 as an output
• Turn the pin HIGH (3.3V) to light the LED
• Turn the pin LOW (0V) to turn it off
• Repeat the cycle with a 1 second delay

Full Code Example

blink.c

#include "pico/stdlib.h"

int main() {
    const uint LED_PIN = 15;
    gpio_init(LED_PIN);
    gpio_set_dir(LED_PIN, GPIO_OUT);

    while (true) {
        gpio_put(LED_PIN, 1);  // Turn LED on
        sleep_ms(1000);
        gpio_put(LED_PIN, 0);  // Turn LED off
        sleep_ms(1000);
    }
}

Build and Upload

1. Create a CMakeLists.txt similar to earlier lessons.

2. Compile your project:

    mkdir build
    cd build
    cmake ..
    make
   

3. Hold BOOTSEL, plug in your Pico
4. Copy the blink.uf2 file to the RPI-RP2 drive

🎉 The LED should start blinking!

Try This

• Change the blink timing (try 250ms)
• Blink multiple LEDs on different pins
• Use a for loop to blink 10 times, then stop

Summary

You’ve now:

• Built a simple electronic circuit
• Controlled it using C
• Completed your first embedded systems project!

Next up: Course Summary and Next Steps

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