🛠 Bandeau NeoPixel piloté par le périphérique RMT

Objectives

Control WS2812 (NeoPixel) addressable LEDs with the ESP32-C3. The Adafruit_NeoPixel library uses the RMT (Remote Control) peripheral on the C3 to generate timing slots with quarter-microsecond precision, without monopolizing the CPU. Avoid the strapping pins (GPIO2, 8, 9) by choosing GPIO7 for the data line.

Hardware

• 1 ESP32-C3 board
• 1 strip of 8 WS2812B LEDs (separate 5 V power supply recommended)
• 1 330 Ω resistor on the data line + 1000 µF capacitor on the power supply
• Adafruit NeoPixel library (Library Manager)

Complete code

#include <Adafruit_NeoPixel.h>

#define PIN_NEO 7      // evite GPIO2/8/9 (strapping) et GPIO9 (BOOT)
#define N     8

Adafruit_NeoPixel strip(N, PIN_NEO, NEO_GRB + NEO_KHZ800);
uint32_t i = 0;

void setup {
  strip.begin;
  strip.setBrightness(40);   // menage l'alimentation
  strip.show;
}

void loop {
  for (uint16_t b = 0; b < N; b++) strip.setPixelColor(b, 0, 0, 0);
  strip.setPixelColor(i % N, strip.Color(255, 60, 0)); // balle orange
  strip.show;
  i++;
  delay(120);
}

Expected verification

An orange LED travels along the strip in a loop. The ESP32-C3 has only one core and runs the Wi-Fi stack in parallel: the RMT generates WS2812 frames without the animation stuttering.

Common errors

• 5 V on the strip's data pin towards the C3: some strips accept 5 V on the data input, but starting from a 3.3 V GPIO remains the standard; never reverse VCC and GND.
• Non-common grounds between the 5 V power supply and the board: LEDs blinking randomly.
• Inverted color order (GRB vs RGB): displayed colors do not match the sent values.
• Data placed on GPIO8: the strip's internal pull-down at rest pulls the strapping pin low and may prevent booting.