PicoW Blink two leds concurrently

LED light not turning on

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Asked 3 days ago

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I was following this tutorial on connecting an external LED to a Pico W, but I’ve had no luck getting it to work.

This is the code I’ve been using:

import machine
from machine import Pin, Timer
timer = Timer()

led = Pin("LED", Pin.OUT)

def blink(timer):
timer.init(freq = 1, mode = Timer.PERIODIC, callback = blink)

Here’s a picture of what I have on the breadboard: [

I’ve tried swapping out the resistor, the LED, the jumpers, and trying all of the GPIO pins 7-15. Forgive the lousy soldering job, I’m quite new at this. My hunch is that the header pins aren’t quite on there right, but want to know if there’s something else I’m missing. Appreciate any help or ideas.



asked Dec 27 at 1:55

Emu_of_Ubiquity's user avatar


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  • 2″Forgive the lousy soldering job” this is the most likely cause of any problems. Resolder all the dry joints, check for shorts. WHY have you soldered a resistor to the Pico? – Milliways Dec 27 at 2:20
  • 2″LED” is NOT a pin. Try one of the standard beginner tutorials. This should have generated an error. – Milliways Dec 27 at 2:22 
  • 2Using “LED” should flash the onboard led. Use a pin number instead of “LED” to specify your required pin. – CoderMike 2 days ago 
  • 2″LED” (with quotes) looks wrong. I’d expect the on-board LED to be named LED (without quotes). – joan 2 days ago

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The OP follows this blink LED tutorial but has no luck. How to debug his code?


Update 2022dec30hkt1534 – Part 3 Concurrently blink 2 Leds Appendix F, G

Part 1 – Try to first blink the onboard LED to make sure the basic pico W hardware/software setup is working OK. If blinking onboard OK, then we can move on checking an external LED connected to a GPIO pin (Appendix A).

Part 2 – Blink GPIO Pin 15 Led

Now that basic Pico hardware/software looks OK, next step is to blink GPIO pin 15 Led. (Appendix C, D)

Appendxi A – Rpi Pico W pinout

picow pinout

Appendix B – Blinking onboard LED

(1) For Pico W, the pin number for on board Led is “WL_GPIO0”.

Yes, no longer number 25 for Pico.

(2) The following program blinks onboard LED. The correct statement to initialize the Led should be:

LED = Pin(“WL_GPIO0”, Pin.OUT)

(3) Full listing of the folly debugged program:

# Name      - Rpi Pico W onboard LED v4.3  tlfong01  2022dec29hkt1502
# Function  - Blink onboard LED
# References -
#   (1) Blink onboard LED  https://projects.raspberrypi.org/en/projects/getting-started-with-the-pico/5
#   (2) Onboard LED pinout https://core-electronics.com.au/guides/raspberry-pi-pico/raspberry-pi-pico-w-overview-features-specs/

import machine
from machine import Pin, Timer
timer = Timer()

LED = Pin("WL_GPIO0", Pin.OUT)

def blink(timer):
timer.init(freq = 1, mode = Timer.PERIODIC, callback = blink)

Appendix C – Blink GPIO Pin 15 Led

# Rpi Pico W Blink GPIO 15 LED v8.0  tlfong01  2022dec29hkt2022

# *** Import modules ***
import machine
from machine import Pin, Timer

# *** Create objects ***
timer02    = Timer()
gp15LedPin = Pin(15, Pin.OUT)

# *** Define functions ***
def blinkGp15Led(dummy):

# *** Blink GP15 Led ***

timer02.init(freq = 2, mode = Timer.PERIODIC, callback = blinkGp15Led)

# *** End of program ***

Appendix D – Blink GPIO Pin 15

enter Blink GPIO Pin 15

Appendix E – Pico W GPIO LED Blink

Appendix F – PicoW Concurrently Blink 2 LEDs

picow blink 2 leds

Appendix G – PicoW Concurrently Blink 2 LEDs Complete Program Listing

# Pico W Concurrently Blink Two LEDs - tlfong01 2022dec30hkt1350

# *** Modules ***
import machine
from machine import Pin, Timer

# *** Objects ***
redTimer    = Timer()
redLed      = Pin(15, Pin.OUT)

greenTimer  = Timer()
greenLed    = Pin(0, Pin.OUT)

# *** Callback Functions ***
def blinkRedLed(dummy):

def blinkGreenLed(dummy):

# *** Main Functions***
redTimer.init(freq = 2, mode = Timer.PERIODIC, callback = blinkRedLed)
greenTimer.init(freq = 4, mode = Timer.PERIODIC, callback = blinkGreenLed)

# *** End of program ***



edited just now

answered yesterday

tlfong01's user avatar


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A 10k resistor will not make the led light up! 10k is way to high!

Change it to a 100 ohm resistor if you have a red LED.



answered 22 hours ago

MatsK's user avatar


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Your LED is wired to the GP13. So try Pin(13, Pin.OUT) instead of Pin("LED", Pin.OUT) 



answered 2 days ago

Mert Aksoy's user avatar

Mert Aksoy

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