利用光线传感器控制呼吸灯

int brightness = 0;    //定义整数型变量brightness与其初始值，此变量用来表示LED的亮度

int fadeAmount = 5;    //定义整数型变量fadeAmount，此变量用来做亮度变化的增减量

int val = 0;

void setup()  {

Serial.begin(9600);// 设置串口波特率

pinMode(0, INPUT);// 设置3号模拟口为输入端口

pinMode(6, OUTPUT);// 设置6号数字口为输出端口

}

void loop()  {

val = analogRead(0);

Serial.print(val);

Serial.println();

if (val > 20) {

analogWrite(6, brightness);//把brightness的值写入6号端口

brightness = brightness + fadeAmount;//改变brightness值，使亮度在下一次循环发生改变

if (brightness == 0 || brightness == 255) {

fadeAmount = -fadeAmount ; //在亮度最高与最低时进行翻转

}

delay(30); //延时30毫秒

}

else

{

digitalWrite(6, HIGH);  // turn the LED on (HIGH is the voltage level)

delay(100);              // wait for a second

digitalWrite(6, LOW);    // turn the LED off by making the voltage LOW

delay(100);              // wait for a second

}

}