5: Blink with Code

Now the RP2040-Zero will control the LED instead of your finger.

In this project, the LED is still a normal circuit, but the “switch” is controlled by code. A GPIO pin can act like an output switch: when your code sets it HIGH, current can flow and the LED can turn on.

Coding ideas you will use:

Learn more (optional):

Goal

Write code that makes an LED blink on and off.

Parts you need

Important: choose the right resistor

Your kit has 150Ω and 100Ω resistors.

  • For a red or yellow LED, use 150Ω
  • For a green, blue, or white LED, use 100Ω

Using the wrong resistor can damage an LED.

Wiring idea

Build it first, then compare your setup to the picture. Did you connect each part to the pin you meant to use?

Use one GPIO pin to control the LED.

Example pin: GP7 (GPIO 7).

Hint

Build circuit 1: Simple LED, but connect the LED to a GPIO pin instead of 3V3.

Example path:

GPIO -> resistor -> LED -> GND

Wiring diagram showing GP7 (GPIO 7) connected through a resistor to an LED, with the LED returning to GND

Code

Pin reminder

Wired your LED to a different GPIO pin? Update LED_GPIO in the code below to match your wiring.

import machine
import time

LED_GPIO = 7

# Set up the pin as an output
led = machine.Pin(LED_GPIO, machine.Pin.OUT)

print("Blinking LED on GPIO", LED_GPIO, "... Press Ctrl+C to stop.")

while True:
    led.value(1)    # Turn LED on
    time.sleep(0.5) # Wait 500ms
    led.value(0)    # Turn LED off
    time.sleep(0.5) # Wait 500ms

Arduino Code Coming Soon

What the code does

Try this

Change the timing values.

Debug tip

If the code runs but the LED does not blink, check that the jumper wire is really connected to the same GPIO pin number used in the code.