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NeoPixel effects

Drive a strip or stick of WS2812 LEDs through a color wipe, a rainbow and a theater chase.

Starter15 min115200 baud

Board

ESP32

3V3

GND

CMD

CLK

Fig. 1. Pins this project uses on the ESP32-DevKitC V4, 38 pin. USB connector at the bottom.

Wiring

From	To board	Note
Strip 5V or VDC	5V	Fine for a few LEDs. A long strip needs its own 5 V supply
Strip GND	GND	Join the grounds if the strip has its own supply
Strip DIN, through 330 Ω	GPIO 16	The resistor goes next to the strip

Tested on this board

Not run on this board yet. Treat the wiring and code as a first draft.

Firmware, Arduino sketch for ESP32 Dev Module

#include <Adafruit_NeoPixel.h>

const int PIN = 16;
const int COUNT = 8;  // LEDs on your strip or stick

Adafruit_NeoPixel strip(COUNT, PIN, NEO_GRB + NEO_KHZ800);

void wipe(uint32_t color) {
  for (int i = 0; i < COUNT; i++) {
    strip.setPixelColor(i, color);
    strip.show();
    delay(60);
  }
}

void rainbow(unsigned long ms) {
  unsigned long start = millis();
  uint16_t hue = 0;
  while (millis() - start < ms) {
    for (int i = 0; i < COUNT; i++) {
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue + i * 65536L / COUNT)));
    }
    strip.show();
    hue += 256;
    delay(20);
  }
}

void chase(uint32_t color, unsigned long ms) {
  unsigned long start = millis();
  int step = 0;
  while (millis() - start < ms) {
    strip.clear();
    for (int i = step % 3; i < COUNT; i += 3) strip.setPixelColor(i, color);
    strip.show();
    step++;
    delay(120);
  }
}

void setup() {
  Serial.begin(115200);
  strip.begin();
  strip.setBrightness(40);  // about 15 %: easy on the eyes and on USB power
  strip.show();
  Serial.printf("%d LEDs on GPIO %d\n", COUNT, PIN);
}

void loop() {
  Serial.println("effect: color wipe");
  wipe(strip.Color(255, 0, 0));
  wipe(strip.Color(0, 255, 0));
  wipe(strip.Color(0, 0, 255));
  Serial.println("effect: rainbow");
  rainbow(5000);
  Serial.println("effect: theater chase");
  chase(strip.Color(255, 160, 0), 4000);
}

3V3

GND

3V3

RST

GND

Fig. 1. Pins this project uses on the ESP32-S3-DevKitC-1, 44 pin. USB connector at the bottom.

Wiring

From	To board	Note
Strip 5V or VDC	5V	Fine for a few LEDs. A long strip needs its own 5 V supply
Strip GND	GND	Join the grounds if the strip has its own supply
Strip DIN, through 330 Ω	GPIO 5	The resistor goes next to the strip

Tested on this board

Not run on this board yet. Treat the wiring and code as a first draft.

Firmware, Arduino sketch for ESP32S3 Dev Module

#include <Adafruit_NeoPixel.h>

const int PIN = 5;
const int COUNT = 8;  // LEDs on your strip or stick

Adafruit_NeoPixel strip(COUNT, PIN, NEO_GRB + NEO_KHZ800);

void wipe(uint32_t color) {
  for (int i = 0; i < COUNT; i++) {
    strip.setPixelColor(i, color);
    strip.show();
    delay(60);
  }
}

void rainbow(unsigned long ms) {
  unsigned long start = millis();
  uint16_t hue = 0;
  while (millis() - start < ms) {
    for (int i = 0; i < COUNT; i++) {
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue + i * 65536L / COUNT)));
    }
    strip.show();
    hue += 256;
    delay(20);
  }
}

void chase(uint32_t color, unsigned long ms) {
  unsigned long start = millis();
  int step = 0;
  while (millis() - start < ms) {
    strip.clear();
    for (int i = step % 3; i < COUNT; i += 3) strip.setPixelColor(i, color);
    strip.show();
    step++;
    delay(120);
  }
}

void setup() {
  Serial.begin(115200);
  strip.begin();
  strip.setBrightness(40);  // about 15 %: easy on the eyes and on USB power
  strip.show();
  Serial.printf("%d LEDs on GPIO %d\n", COUNT, PIN);
}

void loop() {
  Serial.println("effect: color wipe");
  wipe(strip.Color(255, 0, 0));
  wipe(strip.Color(0, 255, 0));
  wipe(strip.Color(0, 0, 255));
  Serial.println("effect: rainbow");
  rainbow(5000);
  Serial.println("effect: theater chase");
  chase(strip.Color(255, 160, 0), 4000);
}

GND

3V3

GND

RST

GND

Fig. 1. Pins this project uses on the ESP32-C3-DevKitM-1, 30 pin. USB connector at the bottom.

Wiring

From	To board	Note
Strip 5V or VDC	5V	Fine for a few LEDs. A long strip needs its own 5 V supply
Strip GND	GND	Join the grounds if the strip has its own supply
Strip DIN, through 330 Ω	GPIO 4	The resistor goes next to the strip

Tested on this board

Not run on this board yet. Treat the wiring and code as a first draft.

Firmware, Arduino sketch for ESP32C3 Dev Module

#include <Adafruit_NeoPixel.h>

const int PIN = 4;
const int COUNT = 8;  // LEDs on your strip or stick

Adafruit_NeoPixel strip(COUNT, PIN, NEO_GRB + NEO_KHZ800);

void wipe(uint32_t color) {
  for (int i = 0; i < COUNT; i++) {
    strip.setPixelColor(i, color);
    strip.show();
    delay(60);
  }
}

void rainbow(unsigned long ms) {
  unsigned long start = millis();
  uint16_t hue = 0;
  while (millis() - start < ms) {
    for (int i = 0; i < COUNT; i++) {
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue + i * 65536L / COUNT)));
    }
    strip.show();
    hue += 256;
    delay(20);
  }
}

void chase(uint32_t color, unsigned long ms) {
  unsigned long start = millis();
  int step = 0;
  while (millis() - start < ms) {
    strip.clear();
    for (int i = step % 3; i < COUNT; i += 3) strip.setPixelColor(i, color);
    strip.show();
    step++;
    delay(120);
  }
}

void setup() {
  Serial.begin(115200);
  strip.begin();
  strip.setBrightness(40);  // about 15 %: easy on the eyes and on USB power
  strip.show();
  Serial.printf("%d LEDs on GPIO %d\n", COUNT, PIN);
}

void loop() {
  Serial.println("effect: color wipe");
  wipe(strip.Color(255, 0, 0));
  wipe(strip.Color(0, 255, 0));
  wipe(strip.Color(0, 0, 255));
  Serial.println("effect: rainbow");
  rainbow(5000);
  Serial.println("effect: theater chase");
  chase(strip.Color(255, 160, 0), 4000);
}

Parts

Quantity	Part	Where to buy
1×	ESP32 dev board	Buy at Amazon
1×	NeoPixel Stick, 8 LEDs, or any WS2812B strip	Buy at Adafruit
1×	330 Ω resistor
1×	Optional 74AHCT125 level shifter	Buy at Adafruit
3×	Jumper wires

Amazon buy links may include an Associates tag, and this site may earn a commission from qualifying Amazon purchases at no extra cost to you. Adafruit links are direct.

Libraries

Adafruit NeoPixel

Load it

In the Arduino IDE, install the esp32 board package and pick the board named above the sketch.
Install the libraries listed above from the Library Manager.
Paste the sketch, choose the board's port and upload. Hold BOOT if the upload stalls at Connecting.
Close the IDE's serial monitor, then open the bench here to watch the output.

Field notes

Each LED can draw about 60 mA at full white. Eight LEDs at the sketch's brightness are fine on USB. A metre or more needs its own 5 V supply and a 1000 µF capacitor across it.
WS2812B LEDs on 5 V expect a data signal near 5 V. Most accept the ESP32's 3.3 V anyway. If the first LED flickers or stays dark, put a 74AHCT125 level shifter in the data line.
No strip yet? The S3 and C3 DevKits have one WS2812 LED on the board: GPIO 38 (or 48 on the first S3 revision) and GPIO 8 on the C3. Set PIN to that and COUNT to 1.
Use a current release of Adafruit NeoPixel. Old releases do not build on the 3.x Arduino core.

Not tested yet

Not tested on hardware yet. Compiles for every board listed with Arduino-ESP32 core 3.3.12.

Open the bench at 115200 baud