Raspberry Pi 3B+ WS2812B Issues

Hi. I’ve spent the last couple evenings trying to build the raspberry pi controlled LED strip using this guide: How To Use Addressable RGB WS2812B LED Strips With a Raspberry Pi Single Board Computer - YouTube but I could not get any lights to light up. My 5 metre strip has 300 lights and am using the strandtest.py file. I followed the guide exactly and have not been able to light up any of the LEDs, with no errors coming from the python file. I’ve even used two separate strips and it doesn’t work with each one.

I have a feeling the issue is because my power supply is 5V 2A, however I’ve even tried to light up just a single LED on the strip and that doesn’t work either.

Any help will be appreciated.

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Okay turns out the issue was my GPIO 18 data pin was faulty, switched to GPIO 21 and everything was fine

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Hey Molly

Welcome to the forums!

I am glad you’ve got that sorted, I know I’ve had issues myself as to output pins being different or faulty between boards. Just something you don’t think about until something doesn’t work.

Best of luck with the LED project and projects in the future,

Hi Molly,

Welcome to the forum :slight_smile:

Page 3 of this datasheet shows the power requirements for WS2812 LEDs.
Each LED on the strip will use 0.6mA even when the LED is off so for 300 LEDs that is a 180mA draw with no light.
When running each colour draws around 12mA (with each LED having 3 colours) which is 10.8 Amps for all 300 LEDs to show white light.

This is similar to the estimates from Adafruit’s NeoPixel Uberguide though they use 20mA per LED max as a rule of thumb and 60mA each for an absolute worst-case, full-power estimate.

Neopixels/Glowbits/WS2812 LEDs use a decent amount of power so driving 300 adds up quickly on the power budget.