Automatic Gate Opener using Arduino

1//Arduino project 4.Automatic open gate.
2
3#define trig 2
4#define  echo 4
5#define led 8
6
7//Servo
8#include <Servo.h>
9
10Servo gate;
11
12
13void  setup() {
14  Serial.begin(9600);
15  
16  pinMode(trig, OUTPUT);
17  pinMode(echo,  INPUT);
18  pinMode(led,OUTPUT);
19  
20  gate.attach(9);
21  
22
23}
24
25void  loop() {
26
27//ultra sonic sensor
28
29  digitalWrite(trig,LOW);
30  delayMicroseconds(2);
31  digitalWrite(trig,HIGH);
32  delayMicroseconds(10);
33  digitalWrite(trig,LOW);
34
35  long t =pulseIn(echo,HIGH);
36
37  long cm = t /29 / 2;
38
39  Serial.print(cm);
40  Serial.println("cm");
41
42//led
43  if (cm <=19){
44    digitalWrite(led,  HIGH);
45   
46  }
47  else{
48    digitalWrite(led,LOW);
49  }
50
51 //Gate
52
53  gate.write(170);
54
55  if (cm<= 19){
56
57    for( int j=170;j>=90;j--){
58      gate.write(j);
59      delay(50);
60    }
61
62    delay(2500);
63    
64    for( int i=90;i<=170;i++){
65    gate.write(i);
66    delay(50);
67  }
68   
69  }
70  else{
71    gate.write(170);
72  }
73
74}
75