#include <FastLED.h> #define LED_PIN 3 #define LED_COUNT 42 #define BRIGHTNESS 255 #define LED_TYPE WS2812B #define COLOR_ORDER GRB CRGB leds[LED_COUNT]; void setup() { FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, LED_COUNT); FastLED.setBrightness(BRIGHTNESS); } void loop() { int brightness = 0; int fadeAmount = 5; while (brightness <= 255) { for (int i = 0; i < LED_COUNT; i++) { leds[i].setRGB(brightness, brightness, brightness); } FastLED.show(); brightness += fadeAmount; delay(25); } while (brightness >= 0) { for (int i = 0; i < LED_COUNT; i++) { leds[i].setRGB(brightness, brightness, brightness); } FastLED.show(); brightness -= fadeAmount; delay(25); } }增加第二条灯带，灯带颜色为黄色，并且一开始是灭的，然后一点一点变亮

可以将代码修改如下：

#include <FastLED.h>  

#define LED_PIN_1     3
#define LED_PIN_2     5
#define LED_COUNT_1   42
#define LED_COUNT_2   42
#define BRIGHTNESS  255
#define LED_TYPE    WS2812B
#define COLOR_ORDER GRB

CRGB leds_1[LED_COUNT_1];
CRGB leds_2[LED_COUNT_2];

void setup() {
  FastLED.addLeds<LED_TYPE, LED_PIN_1, COLOR_ORDER>(leds_1, LED_COUNT_1);
  FastLED.addLeds<LED_TYPE, LED_PIN_2, COLOR_ORDER>(leds_2, LED_COUNT_2);
  FastLED.setBrightness(BRIGHTNESS);
}

void loop() {
  int brightness_1 = 0;
  int brightness_2 = 0;
  int fadeAmount = 5;

  while (brightness_1 <= 255) {
    for (int i = 0; i < LED_COUNT_1; i++) {
      leds_1[i].setRGB(brightness_1, brightness_1, brightness_1);
    }
    FastLED.show();
    brightness_1 += fadeAmount;
    delay(25);
  }

  while (brightness_2 <= 255) {
    for (int i = 0; i < LED_COUNT_2; i++) {
      leds_2[i].setRGB(255, 255, 0);
      leds_2[i].fadeLightBy(brightness_2);
    }
    FastLED.show();
    brightness_2 += fadeAmount;
    delay(25);
  }

  while (brightness_1 >= 0) {
    for (int i = 0; i < LED_COUNT_1; i++) {
      leds_1[i].setRGB(brightness_1, brightness_1, brightness_1);
    }
    FastLED.show();
    brightness_1 -= fadeAmount;
    delay(25);
  }
}

这个代码会将第一条灯带一点一点变亮，然后第二条灯带从灭的状态开始，一点一点变成黄色并且变亮，最后第一条灯带再一点一点变暗。注意，需要在代码中添加第二条灯带的引脚和数量，并且使用 `fadeLightBy()` 函数来让灯带一点一点变亮。