led灯亮度渐变实现

所需硬件

• Arduino或者Genuino开发板

• LED

• 220欧电阻

• 导线

• 实验电路板

代码

int led = 9;           // the PWM pin the LED is attached to
int brightness = 0;    // how bright the LED is
int fadeAmount = 5;    // how many points to fade the LED by 
// the setup routine runs once when you press reset:
void setup() {  
// declare pin 9 to be an output:  
pinMode(led, OUTPUT);
} 
// the loop routine runs over and over again forever:
void loop() {  
// set the brightness of pin 9:  
analogWrite(led, brightness);   
// change the brightness for next time through the loop:  
brightness = brightness + fadeAmount;   
// reverse the direction of the fading at the ends of the fade:  
if (brightness == 0 || brightness == 255) {    
fadeAmount = -fadeAmount ;  
}  
// wait for 30 milliseconds to see the dimming effect  
delay(30);
}

实验效果图

led灯由暗变亮