#include <Arduino.h>
#include <Adafruit_NeoPixel.h>

// --- config ---
#define LED_PIN       3        // your NeoPixel data pin
#define NUM_PIXELS    1        // change if you have more
#define BRIGHTNESS    30       // 0..255 (keep modest if powered from USB)

// Most WS2812/NeoPixel strips are GRB @ 800 kHz:
#define PIXEL_TYPE    (NEO_GRB + NEO_KHZ800)

Adafruit_NeoPixel strip(NUM_PIXELS, LED_PIN, PIXEL_TYPE);

static void solid(uint32_t c, uint16_t ms) {
  for (uint16_t i = 0; i < NUM_PIXELS; i++) strip.setPixelColor(i, c);
  strip.show();
  delay(ms);
}

void setup() {
  strip.begin();
  strip.setBrightness(BRIGHTNESS);
  strip.show(); // all off

  // Quick RGB sanity check (each color ~300 ms)
  solid(strip.Color(255,   0,   0), 300);  // Red
  solid(strip.Color(  0, 255,   0), 300);  // Green
  solid(strip.Color(  0,   0, 255), 300);  // Blue
  solid(strip.Color(  0,   0,   0), 200);  // Off
}

void loop() {
  // Smooth rainbow using HSV -> RGB with gamma correction
  static uint16_t hue = 0;              // 0..65535
  uint32_t c = strip.gamma32(strip.ColorHSV(hue));
  for (uint16_t i = 0; i < NUM_PIXELS; i++) strip.setPixelColor(i, c);
  strip.show();

  hue += 256;                           // step size (smaller = slower)
  delay(20);                            // frame rate (~50 FPS)
}