WS2812B LED strip with LOLIN S2 Mini

WS2812B strips need 5 V power and one data line. On the S2 Mini send data from GPIO5 through 330 Ω and run the strip from a separate 5 V adapter with a common ground.

The sketch runs a rainbow at about 25 % brightness and blinks the S2 Mini’s blue LED (GPIO15) slowly so you know the code is running.

Wiring

Also needed: 330 Ω resistor, 1000 µF / 10 V capacitor, 5 V 2 A adapter.

Every connection
LOLIN S2 Mini	WS2812B addressable RGB LED strip (NeoPixel)	Wire	Notes
5	DIN	green	Via 330 Ω
5 V 2 A adapter · +5V	5V	red	1000 µF capacitor across 5V/GND at the strip.
5 V 2 A adapter · GND	GND	black
GND	GND	black	Common ground with the S2 Mini.

5 V (about 60 mA per LED at full white) part, 3.3 V board. The strip expects a data HIGH of about 3.5 V at 5 V supply. From ESP32 or Pico the 3.3 V signal often works with short wires, but to be safe drive DIN through a 74AHCT125 (or 74HCT125) powered from 5 V.

Board quirks

Don’t feed 5 V into VBUS while USB is plugged in: the S2 Mini has no reverse-current diode there. With the strip on its own supply and only GND shared, that problem never comes up.
GPIO5 (D1 mini D0 position) has no boot role. The WS2812 D1 mini shield uses a different position — check its jumper and change STRIP_PIN to match.
The S2’s 3.3 V data usually drives a strip on a short wire; if the first LED flickers, add a 74AHCT125 buffer.

Code

ws2812b-s2mini.inoArduino C++Open in Playground Flash

// WS2812B strip on a LOLIN S2 Mini.
// DIN → GPIO5 through 330 Ω. Strip 5V/GND → its own 5 V supply; supply GND → S2 Mini GND.
#include <Adafruit_NeoPixel.h>

constexpr uint8_t STRIP_PIN = 5;
constexpr uint16_t COUNT = 30;
Adafruit_NeoPixel strip(COUNT, STRIP_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  Serial.begin(115200);
  uint32_t t0 = millis();
  while (!Serial && millis() - t0 < 3000) {}
  strip.begin();
  strip.setBrightness(60);
  strip.show();
  pinMode(LED_BUILTIN, OUTPUT);  // blue LED on GPIO15
  Serial.printf("WS2812B: %u LEDs on GPIO5\n", COUNT);
}

void loop() {
  static uint16_t hue = 0;
  for (uint16_t i = 0; i < COUNT; i++) {
    strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue + i * 65536UL / COUNT)));
  }
  strip.show();
  digitalWrite(LED_BUILTIN, (hue >> 14) & 1);  // slow heartbeat on the blue LED
  hue += 256;
  delay(20);
}

// WS2812B strip on a LOLIN S2 Mini.
// DIN → GPIO5 through 330 Ω. Strip 5V/GND → its own 5 V supply; supply GND → S2 Mini GND.
#include <Adafruit_NeoPixel.h>

constexpr uint8_t STRIP_PIN = 5;
constexpr uint16_t COUNT = 30;
Adafruit_NeoPixel strip(COUNT, STRIP_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  Serial.begin(115200);
  uint32_t t0 = millis();
  while (!Serial && millis() - t0 < 3000) {}
  strip.begin();
  strip.setBrightness(60);
  strip.show();
  pinMode(LED_BUILTIN, OUTPUT);  // blue LED on GPIO15
  Serial.printf("WS2812B: %u LEDs on GPIO5\n", COUNT);
}

void loop() {
  static uint16_t hue = 0;
  for (uint16_t i = 0; i < COUNT; i++) {
    strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue + i * 65536UL / COUNT)));
  }
  strip.show();
  digitalWrite(LED_BUILTIN, (hue >> 14) & 1);  // slow heartbeat on the blue LED
  hue += 256;
  delay(20);
}

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

Expected serial output

Serial Monitor · 115200Output

WS2812B: 30 LEDs on GPIO5

WS2812B: 30 LEDs on GPIO5

Common errors

Strip lights random colours at power-up, then works

Normal before the sketch starts. The 330 Ω resistor and the capacitor reduce it.

S2 Mini resets when the strip goes white

Strip is drawing from the board. Use its own supply. Brownout fix.