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How to calculate the amperes from Arduino to supply WS2812B
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How to calculate the amperes from Arduino to supply WS2812B

by noobie on Fri Sep 24, 2021 2:26 am

I have 3 Neopixel LED rings that have 12, 16, and 24 LEDs.

I am using Arduino pro mini (5V) and all the rings are supplied by the Vcc pin of the Arduino.
I am using 1kOhm resistors btw the arduino and the ring-DIN pins for safety.

The rings should work flawlessly at their highest white brightness.
In the uberguide; it is said that:

But if you know for a fact that you need every pixel on at maximum brightness, use the full 60 mA figure.
To estimate power supply needs, multiply the number of pixels by 20, then divide the result by 1,000 for the “rule of
thumb” power supply rating in Amps. Or use 60 (instead of 20) if you want to guarantee an absolute margin of safety
for all situations. For example:
60 NeoPixels × 20 mA ÷ 1,000 = 1.2 Amps minimum
60 NeoPixels × 60 mA ÷ 1,000 = 3.6 Amps minimum


Here is my noobie question:
The rings are working fine now. But I read that arduino-pro-mini supplies max 40mA in each IO pin. Here I have a lot of mAmps...

How can it be working now? Or will it be working for a short period of time? Is it not healthy to use pro-mini to drive the rings?

noobie
 
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Re: How to calculate the amperes from Arduino to supply WS28

by adafruit_support_bill on Fri Sep 24, 2021 6:45 am

The rings are working fine now. But I read that arduino-pro-mini supplies max 40mA in each IO pin. Here I have a lot of mAmps...

How can it be working now?

The GPIO pin is not supplying current to the pixels. It is only providing the control signal. The current is coming via the 5v pin.

adafruit_support_bill
 
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Joined: Sat Feb 07, 2009 10:11 am

Please be positive and constructive with your questions and comments.