Arduino PWM输出

以下代码每隔100毫秒向PD3口发送PWM(0 ~ 255)的递增脉冲值 LED会从暗到亮 无限循环并将每次递增的值写到baud 9600串口

int led = PD3;
int pwm = 0;

void setup()
{
    pinMode(led, OUTPUT);
    Serial.begin(9600);
    digitalWrite(led, LOW);
}

void loop()
{
    analogWrite(led, pwm+=30);
    Serial.println(pwm);
    delay(100);
    if (pwm >= 255)
    {
        pwm = 0;
    }
}