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LED Blink Example

Basic LED control example for Raspberry Pi Pico.

Overview

This is the simplest example demonstrating how to control the onboard LED on the Raspberry Pi Pico.

Source Code

File: src/pico_scripts/01_blink.py

Features

  • Control onboard LED
  • Two modes: blink N times or blink forever
  • Configurable blink speed
  • Clean error handling with Ctrl+C

Hardware Requirements

  • Raspberry Pi Pico or Pico W
  • Micro USB cable
  • No external components needed (uses onboard LED)

Code Explanation

LED Setup

import machine

# For Pico W, use "LED"
# For regular Pico, use Pin(25)
led = machine.Pin("LED", machine.Pin.OUT)

Blink N times: 

def blink_led(times=10, delay=0.5):
    for i in range(times):
        led.on()
        time.sleep(delay)
        led.off()
        time.sleep(delay)

Blink continuously: 

def blink_forever(on_time=0.5, off_time=0.5):
    while True:
        led.on()
        time.sleep(on_time)
        led.off()
        time.sleep(off_time)

Usage

Upload to Pico

  1. Open 01_blink.py in Thonny
  2. Connect your Pico via USB
  3. Click "Run current script" (F5)
  4. LED should start blinking!

Edit the main section:

# Blink 5 times slowly
blink_led(times=5, delay=1.0)

# Or blink continuously fast
blink_forever(on_time=0.2, off_time=0.2)

Stop the Program

Press Ctrl+C in Thonny Shell to stop the blinking.

Autostart on Power-Up

To make this run automatically when Pico powers on:

  1. Save the file as main.py on the Pico
  2. Disconnect and reconnect USB
  3. LED will start blinking automatically

Troubleshooting

LED Not Blinking

Check: - Pico is properly connected - Code is running (check Thonny Shell for output) - Using correct Pin ("LED" for Pico W, 25 for regular Pico)

Try: 

# Test LED manually in Shell
from machine import Pin
led = Pin("LED", Pin.OUT)
led.on()   # Should turn on
led.off()  # Should turn off

Program Won't Stop

  • Press Ctrl+C multiple times
  • Click "Stop/Restart backend" in Thonny
  • Disconnect USB cable

Next Steps

Reference

See full source code: src/pico_scripts/01_blink.py