Powering neopixels off a Feather Huzzah

Discussion Electronics
1

I’m working on a project which involves running neopixels strips off a Feather Huzzah. I don’t know exactly how many yet, but we’re looking at around 80 (I think).

With this in mind, what’s the best way of supplying power to both the neopixels as well as the Huzzah?

My understanding if you’re able to run around 5 of them off the 3.3v pin without too much trouble (in fact I have a string of 8 of them running just fine at half brightness), but as I need around ten times this number, I wanted to make sure I wasn’t going to do anything stupid.

I’ve seen references to something called a logic level shifter (TXB0104 specifically), which should be used when trying to run more than 5 - which I believe is responsible for switching the 3.3v up to 5v - but I’m not sure if this is all I’m going to need - or if there’s a better way of solving the issue.

Can someone provide me with some guidance please? Thank you.

2

You need an external power supply, as 80 LEDs will consume 4.8 Amps. You will need a series resistor of about 470R in the data line. You will need at least 1000uF capacitor across the power supply.
You might get away with not having a level shifter but if running off 5V then the signal you get from a 3V3 processor is just under the minimum guaranteed specification for the data pin voltage.

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3

Can you make a suggestion on the type of power supply you’d recommend? And how it should be connected (ideally I want one plug which powers both the huzzah and the neopixels.

Also, what’s the purpose of the resistor on the data line?

Thanks.

4

See https://learn.adafruit.com/adafruit-neopixel-uberguide especially the power chapter.
The 1000uF capacitor and 470 Ohm resistor are explained there.

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