PIR Sensor Integration

1//Interface a PIR sensor to detect motion and display "Motion detected"  or
2//"No motion" depending on the output from the sensor
3
4#include <LiquidCrystal.h>
5
6//variable  declarations
7uint8_t readPIR = 0;
8uint8_t nomotionflag = 0;
9const int RS  = 2, EN = 3, D4 = 4, D5 = 5, D6 = 6, D7 = 7;
10
11LiquidCrystal lcd(RS,EN,D4,D5,D6,D7);   //set Uno pins that are connected to LCD, 4-bit mode
12
13void setup() {
14  lcd.begin(16,2);          //set 16 columns and 2 rows of 16x2 LCD
15  pinMode(8,  INPUT);        //output of PIR sensor (input to Uno)
16  pinMode(9, OUTPUT);       //input  to PIR sensor to enable (output of Uno)
17  digitalWrite(9, HIGH);    //enable  PIR sensor
18
19}
20
21void loop() {
22  readPIR = digitalRead(8);   //check  if motion detected
23  
24  if (readPIR == 1){          //motion detected
25    nomotionflag = 0;         //reset flag
26    lcd.home();
27    lcd.print("Motion  Detected");
28    delay(500);
29  }
30
31  else{                         //no  motion detected
32    if (nomotionflag == 0){       
33      lcd.clear();
34      lcd.print("No motion");
35      nomotionflag = 1;
36    }
37    
38  }
39  
40}