By tlfong01 on December 29, 2022 • ( Leave a comment )

LED light not turning on

Asked 2 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):
    led.toggle()
    
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.

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asked 2 days ago

Emu_of_Ubiquity

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1″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 2 days ago
1″LED” is NOT a pin. Try one of the standard beginner tutorials. This should have generated an error. – Milliways 2 days ago
1Using “LED” should flash the onboard led. Use a pin number instead of “LED” to specify your required pin. – CoderMike 2 days ago
1″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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Question

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

Answer

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.

Appendxi A – Rpi Pico W 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):
    LED.toggle()
    
timer.init(freq = 1, mode = Timer.PERIODIC, callback = blink)

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edited 2 mins ago

answered 3 hours ago