题目：说出以下三基色LED灯（共阴）渐变程序的运行效果，并阐述其控制原理。#define LED_R 3#define LED_G 5#define LED_B 6int PWMValue=0;void setup(){analogWrite(LED_R, 0);analogWrite(LED_G, 0);analogWrite(LED_B, 0);}void loop(){int i=0;PWMValue=0;for(i=0;i<255;i++){analogWrite(LED_R, 0);analogWrite(LED_G, PWMValue++);analogWrite(LED_B, 0);delay(10);}PWMValue=255;for(i=0;i<255;i++){analogWrite(LED_R, 0);analogWrite(LED_G, PWMValue--);analogWrite(LED_B, 0);delay(10);}}
喵查答案：["LED灯显示绿色从亮到灭变化。运用PWM脉宽调制原理，实现颜色渐变效果。PWM是利用微处理器的数字输出来对模拟电路进行控制。输出的电压值是通过通和断的时间来进行计算。计算公式：输出电压=（接通时间/脉冲时间）×最大电压"]