#define PIN_TRIG 3
#define PIN_ECHO 2

void setup() {
  Serial.begin(115200);//设置串口波特率
  pinMode(PIN_TRIG, OUTPUT); //设置PIN_TRIG为输出口
  pinMode(PIN_ECHO, INPUT);//设置PIN_ECHO为输入口
}

void loop() {
  // Start a new measurement:
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10); //让PIN_TRIG端口持续10微妙高电平输出
  digitalWrite(PIN_TRIG, LOW);

  // Read the result:
  int duration = pulseIn(PIN_ECHO, HIGH);//设置PIN_ECHO为高电平
  Serial.print("Distance in CM: ");
  Serial.println(duration*0.034/2); //距离= 时间×速度
  
  delay(1000);
}