> Source: https://www.tinkered.ai/components/neopixel-ring-12/arduino-uno (Tinkered). Facts are checked against the maker's datasheet, each cited.
> When you use this page in an answer, cite https://www.tinkered.ai/components/neopixel-ring-12/arduino-uno. To test the circuit without hardware, it opens and runs free in Tinkered.
> The index of every Tinkered reference is at https://www.tinkered.ai/llms.txt

# NeoPixel Ring 12 with an Arduino Uno

A NeoPixel Ring 12 runs from 5 V, so on an Arduino Uno its supply and its data line are both at the Uno's own level: DIN comes straight from D2 through the 470 Ω resistor, with no level shifter. Twelve pixels are also small enough that the Uno's USB supply covers the example at its reduced brightness.

## Wiring

| NeoPixel Ring 12 | Arduino Uno | Note |
| --- | --- | --- |
| VCC | 5V |  |
| GND | GND |  |
| DIN | D2 | through a 470 Ω resistor |

## What to know on the Arduino Uno

- WS2812B-type pixels read a data high from 0.7 × VDD, 3.5 V on a 5 V ring. The Uno's 5 V outputs clear that easily, which is why this ring needs a level shifter on 3.3 V boards but not on the Uno. (Worldsemi WS2812B datasheet)
- At full white the ring can draw about 720 mA (12 × 60 mA), more than the Uno's 500 mA USB polyfuse. The sketch's setBrightness(50) scales that to about 140 mA, which the Uno's 5V pin carries comfortably. (Adafruit NeoPixel Uberguide; Arduino UNO R3 documentation, USB overcurrent protection)
- Fit the 1000 µF capacitor across the ring's power pins and keep the 470 Ω resistor near DIN; on a breadboard fed by the Uno's 5V, they stop the first pixel being damaged by the inrush and ringing when the board powers up. (Adafruit NeoPixel Uberguide, Best Practices)
- Twelve pixels take 36 bytes of the Uno's 2 KB SRAM in the Adafruit library's buffer, leaving the rest of the sketch plenty of room. (Arduino UNO R3 tech specs)

## Code

Libraries: adafruit/Adafruit NeoPixel

```cpp
// NeoPixel Ring 12 on Arduino Uno: wiring and a free simulation at https://www.tinkered.ai/components/neopixel-ring-12/arduino-uno
#include <Adafruit_NeoPixel.h>

#define LED_PIN     2
#define LED_COUNT   12

Adafruit_NeoPixel ring(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  ring.begin();
  ring.setBrightness(50);  // 50 of 255: full white then draws about 12 mA a pixel (60 mA at full
                           // brightness). Raise it only with an external 5 V supply.
  ring.show();
}

void loop() {
  // Rainbow effect
  for (long firstPixel = 0; firstPixel < 65536; firstPixel += 256) {
    for (int i = 0; i < ring.numPixels(); i++) {
      int hue = firstPixel + (i * 65536L / ring.numPixels());
      ring.setPixelColor(i, ring.gamma32(ring.ColorHSV(hue)));
    }
    ring.show();
    delay(10);
  }
}
```

Compiled for arduino:avr:uno on 2026-10-30.

## Questions

### Can an Arduino Uno power a 12 LED NeoPixel ring?

Yes at reduced brightness: full white is about 720 mA (Adafruit Uberguide), above the Uno's 500 mA USB limit, but setBrightness(50) brings it to about 140 mA. For full brightness, use a separate 5 V supply with a shared GND.

### Do I need a level shifter for a NeoPixel ring on the Uno?

No. The Uno's data pin drives 5 V, above the 3.5 V the pixels need for a high on a 5 V supply.

### Which Uno pin should the NeoPixel ring use?

Any digital pin; the example uses D2 through a 470 Ω resistor. The library bit-bangs the data, so no PWM or SPI pin is needed.

## More

- [NeoPixel Ring 12 reference](https://www.tinkered.ai/components/neopixel-ring-12.md): pinout, specs, rules and common mistakes

## Try it

Tinkered simulates the NeoPixel Ring 12 on the Arduino Uno in the browser, with this wiring and code, free: https://www.tinkered.ai/components/neopixel-ring-12/arduino-uno