int minlight = 0;//最小亮度
int maxlight = 255;//最大亮度
float breatheStep = 0.5;//亮度变化值
int delayTime = 1;//每个亮度保持时间，这其实也是一个一个阶梯型电平组成的大连续信号
 
void setup()
{
	pinMode(3, OUTPUT);
	pinMode(5, OUTPUT);
	pinMode(6, OUTPUT);//接上三个LED
}
 
void loop()
{
	breathing(3);
	breathing(5);
	breathing(6);//三个LED依次亮度变化
}
 
void breathing(int pincode )
{
	for (float light = 0; light <= maxlight ; light = light + breatheStep )//逐渐变亮，电压由0到百分之百
	{
		analogWrite(pincode, light);
		delay(delayTime);
	}
	
	for (float light = 255; light >= minlight; light = light - breatheStep)//逐渐变暗，电压由百分之百到0
	{
		analogWrite(pincode, light);
		delay(delayTime);
	}
}