#include <Arduino.h>

int sensorpin = 8;
int ledpin = 9;
bool sensorOutput;

void setup() {
Serial.begin(9600);
pinMode(sensorpin, INPUT);
pinMode(ledpin, OUTPUT);
}

void loop() {
sensorOutput = digitalRead(sensorpin);

if(sensorOutput == HIGH){
  Serial.println("有人！");
  digitalWrite(ledpin, HIGH);
}else{
  Serial.println("无人...");
  digitalWrite(ledpin, LOW);
}
delay(10);
}