HC-SR04是一个超声波测距模块

接线

HC-SR04 Arduino
VCC 5v
GND GND
Trig PIN8
Echo PIN9

程序

const int TP = 8;
const int EP = 9;

void setup()
{
    pinMode(TP, OUTPUT);
    pinMode(EP, INPUT);

    Serial.begin(9600);
}

void loop()
{
    digitalWrite(TP, LOW);
    delayMicroseconds(2);

    digitalWrite(TP, HIGH);
    delayMicroseconds(10);

    digitalWrite(TP, LOW);

    long microseconds =  pulseIn(EP, HIGH);
    Serial.print("ret=");
    Serial.println(microseconds);

    long distacne = microseconds / 2 / 29.1;  // 计算距离公式
    Serial.print("distacne=");
    Serial.print(distacne);
    Serial.println("cm");
    delay(1000);
}

参考: http://www.elecfreaks.com/244.html

素材: https://github.com/rngadam/ART/tree/master/ele/fritzing/HC-SR04