WS2812B (NeoPixel) LED strip with ESP32 — wiring and rainbow code

WS2812B strips put a tiny controller inside every LED, so one GPIO drives the whole strip. The ESP32 handles the 800 kHz timing in hardware.

Two things matter on an ESP32: power (each LED can draw 60 mA, so anything beyond a short strip needs its own 5 V supply with a shared ground) and logic level (the strip is 5 V, the ESP32 is 3.3 V — usually fine on short wires, with a buffer as the fix if not).

Wiring

Board quirks

• The strip runs at 5 V and expects at least about 3.5 V for a logic HIGH; the ESP32’s 3.3 V usually works on short wires. If the first LED flickers, add a 74AHCT125 buffer powered from 5 V.
• Brightness is capped at 40/255 so 8 LEDs stay well under 500 mA — full white is about 60 mA per LED.
• The ESP32 core sends NeoPixel data with the RMT peripheral, so Wi-Fi doesn’t disturb the timing.

Code

// WS2812B LED strip (8 LEDs) on an ESP32 DevKit V1.
// DIN → D13 through a 330 Ω resistor, strip 5V → VIN (short strip only), GND → GND.
#include <Adafruit_NeoPixel.h>

constexpr uint8_t LED_PIN = 13;
constexpr uint16_t LED_COUNT = 8;

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

void setup() {
  Serial.begin(115200);
  strip.begin();
  strip.setBrightness(40);  // keeps current low on USB power (~20 mA per LED at this level)
  strip.show();
  Serial.println("WS2812B rainbow on GPIO13");
}

void loop() {
  static uint16_t hue = 0;
  for (uint16_t i = 0; i < LED_COUNT; i++) {
    strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue + i * 65536UL / LED_COUNT)));
  }
  strip.show();
  hue += 256;
  delay(20);
}

// WS2812B LED strip (8 LEDs) on an ESP32 DevKit V1.
// DIN → D13 through a 330 Ω resistor, strip 5V → VIN (short strip only), GND → GND.
#include <Adafruit_NeoPixel.h>

constexpr uint8_t LED_PIN = 13;
constexpr uint16_t LED_COUNT = 8;

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

void setup() {
  Serial.begin(115200);
  strip.begin();
  strip.setBrightness(40);  // keeps current low on USB power (~20 mA per LED at this level)
  strip.show();
  Serial.println("WS2812B rainbow on GPIO13");
}

void loop() {
  static uint16_t hue = 0;
  for (uint16_t i = 0; i < LED_COUNT; i++) {
    strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue + i * 65536UL / LED_COUNT)));
  }
  strip.show();
  hue += 256;
  delay(20);
}

Library: Adafruit NeoPixel (Adafruit) — compiled with Adafruit NeoPixel 1.15.5.

Expected serial output

WS2812B rainbow on GPIO13

WS2812B rainbow on GPIO13

Common errors