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Raspberry Pi Pico: Controlling an External LED (GP14 + Breadboard)

The next step after Pico’s built-in LED: connecting an external LED to the breadboard and controlling it via the GP14 pin. In this project, you’ll learn how to use any of the Pico’s general-purpose GPIO pins as an output, the LED’s polarity (long leg = anode/+, short leg = cathode/–), and why a current-limiting resistor (220Ω) is required. If you don’t include the resistor, excessive current will flow through the LED and it may burn out. The circuit is very simple: Pico GP14 → 220Ω resistor → LE

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Raspberry Pi Pico: Controlling an External LED (GP14 + Breadboard)
The next step after Pico’s built-in LED: connecting an external LED to the breadboard and controlling it via the GP14 pin. In this project, you’ll learn how to use any of the Pico’s general-purpose GPIO pins as an output, the LED’s polarity (long leg = anode/+, short leg = cathode/–), and why a current-limiting resistor (220Ω) is required. If you don’t include the resistor, excessive current will flow through the LED and it may burn out. The circuit is very simple: Pico GP14 → 220Ω resistor → LED (+) → LED (–) → Pico GND. You can simulate this in Wokwi and test it on a real breadboard using the same connection. In MicroPython, we define the pin as an output using `machine.Pin(14, Pin.OUT)`—this way, we can easily control multiple LEDs (traffic lights, running LEDs) in a future project.

Video

Circuit Diagram

Raspberry Pi Pico: Controlling an External LED (GP14 + Breadboard) - Circuit

Source Code

MicroPython
1# ─────────────────────────────────────────
2#   BlueGrays · bluegrays.com
3#   Raspberry Pi Pico: Controlling an External LED (GP14 + Breadboard)
4# ─────────────────────────────────────────
5# An external LED on a breadboard blinks every 0.5 s. Shows how to use any
6# Pico GPIO pin as an output.
7#
8# Pins:
9#   GP14 -> 220 ohm resistor -> LED (+, long leg)
10#   Red LED (-, short leg) -> GND
11
12from machine import Pin
13import time
14
15# ============ PIN / PIN ============
16LED_PIN = 14                    # Any free GPIO
17led = Pin(LED_PIN, Pin.OUT)
18
19print("== BlueGrays: Pico Harici LED Blink ==")
20print("LED pin: GP" + str(LED_PIN))
21print("500ms yakip 500ms sonduruyor / 500ms on 500ms off")
22
23# ============ MAIN LOOP ============
24while True:
25    led.on()                    # Turn the LED on
26    print("[LED] ACIK / ON")
27    time.sleep(0.5)
28
29    led.off()                   # Turn the LED off
30    print("[LED] KAPALI / OFF")
31    time.sleep(0.5)
32

FAQ

What is the voltage output of the Pico's pins?▾

The Pico's GPIO pins operate on a 3.3 V logic level. Applying a 5 V signal directly to a Pico pin can damage the pin; a level shifter or voltage divider must be used for 5 V sensors.

How much current can I draw from a Pico pin?▾

The GPIO drive strength setting does not make the pin a constant-current source or a current limiter. LED current depends on the output voltage, the LED's forward voltage, and the series resistor: with a 3.3 V output, a forward voltage of approximately 2 V, and a 220 Ω resistor, the estimated current is (3.3 V - 2 V) / 220 Ω = 5.9 mA. Use a suitable driver for more powerful loads.

Can I use a different pin instead of GP14?▾

Yes, all pins between GP0–GP22 and GP26–GP28 can be used as outputs. When you change the pin number, be sure to update the line Pin(14, Pin.OUT) in the code as well.

Are the physical pin number and the GP number the same?▾

No. The code uses a GP number (e.g., GP14), which corresponds to the 19th physical pin on the card. The text on the back of the card and the pinout diagram show the GP numbers.

Raspberry Pi Pico: Controlling an External LED (GP14 + Breadboard) | BlueGrays