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funhouse -- neopixel strip won't light when using JST ports
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funhouse -- neopixel strip won't light when using JST ports

by aoc on Fri Oct 15, 2021 7:30 pm

I have exactly the problem described in https://forums.adafruit.com/viewtopic.php?f=47&t=179752. Unfortunately that thread was locked without a resolution. I'm happy to post the code and precise hardware in use but it is identical to the problem mattlewis describes in the linked thread. The strip is a known-good 30-pixel strip that came with the magtag adabox, and the same code works when I plug a strip in to the PIR port on the funhouse. Thanks!

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Re: funhouse -- neopixel strip won't light when using JST po

by dastels on Fri Oct 15, 2021 8:56 pm

I see a couple potential problems:

- The Vcc on the 3-pin JST connectors is 5v by default, while the data signal is 3.3v logic. I would expect problems from NeoPixels connected to that. You can change the connectors to use 3.3v for Vcc by using the 3.3v/5v jumpers on the back of the board between the A0 and A1 connectors: cut the 5v trace and solder bridge the 3.3v side.
- The maximum current you can get from the 3-pin JST connectors is 200mA. The max current demand per NeoPixel is 60mA (3 LEDs, each ~20mA). That's worst case with the NeoPixel full brightness white (i.e. a color of (255, 255, 255)). This guide discusses approaching to using less current/power when using NeoPixels: https://learn.adafruit.com/sipping-power-with-neopixels.

You can get the NeoPixels working on the PIR port likely due to it using 3.3v for it's Vcc connection.

I would change the voltage and keep an eye on the power being used.

Dave

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Re: funhouse -- neopixel strip won't light when using JST po

by kclarkfl on Tue Oct 19, 2021 9:55 pm

Side note, powering the Funhouse, driving the 1 meter NeoPixels, from the RPi-4 power supply sold by Adafruit, and the Funhouse runs fine, but the Neopixel strip on A1 does not light. Powering the NeoPixel strip from a computer USB port, from from an Apple 5V 1A power supply, and they light fine. I guess the RPi4 power supply (the official RPi4 USB-C power supply) has too high of voltage? Or a 'glitch' on startup up? I tried both pulling and unplugging on the AC end of the power supply, and the USB end. And hitting the reset button on the FunHouse itself. No difference, no NeoPixel strip. I did startup the NeoPixels in the off state, and am running at very low brightness (0.01).

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Please be positive and constructive with your questions and comments.