This sample code is for Detecting People Using PIR Sensor's Tutorial by Cytron Technologies Sdn. Bhd.

PIR.ino

/*
  This example code is for Detecting People with PIR Motion Sensor.
  Product page:
  Maker UNO: https://www.cytron.io/p-maker-uno
  PIR Sensor : https://www.cytron.io/p-sn-pir
  Created by:
  23/08/18  Suad Anwar, Cytron Technologies
*/

int Buzzer = 8;                     // choose the pin for the LED
int PIRpin = 5;                     // choose the input pin (for PIR sensor)
int PIRstate = 0;                   // we start, assuming no motion detected

void setup() {
  pinMode(Buzzer, OUTPUT);          // initialize the LED pin as an output:
  pinMode(PIRpin, INPUT);           // initialize the PIR sensor pin as an input:
}

void loop() {
  PIRstate = digitalRead(PIRpin);   // read the state of the pushbutton value:

  // check if the PIR sensor is triggered. If it is, the PIRstate is HIGH:
  if (PIRstate == HIGH) {
    tone(Buzzer, 494, 700);
    delay(900);
    tone(Buzzer, 392, 900);
    delay(1300);
  
  } else {
    noTone;
  }
}