Simple DIY Project Using HC-SR04 Ultrasonic Sensor

1int echoPin = 2;  //Define Echo pin
2int trigPin = 3;     // Define  Trig pin
3long  inches, duration, cm;   //Define variables
4int height=300;  //define depth of tank in cm
5int firstLED = 4; // define LEDs pin
6int secondLED  = 5;
7int thirdLED = 6;
8int fourthLED = 7;
9
10void setup() {
11
12Serial.begin  (9600);
13pinMode(trigPin, OUTPUT);  //Define output pin
14pinMode(firstLED, OUTPUT);
15pinMode(secondLED,  OUTPUT);
16pinMode(thirdLED, OUTPUT);
17pinMode(fourthLED, OUTPUT);
18pinMode(echoPin,  INPUT);  //Define input pin
19
20}
21
22
23void loop()
24{
25//Give a short  low pulse  to trigPin for ensure a clean high pulse
26digitalWrite(trigPin, LOW);
27delayMicroseconds(5);
28
29//give  high pulse to trigPin 10 microseconds
30digitalWrite(trigPin, HIGH);
31delayMicroseconds(10);
32
33digitalWrite(trigPin,  LOW);
34
35// Read the signal from the sensor
36duration = pulseIn(echoPin, HIGH);
37
38//  convert time into a distance
39// The speed of sound is 29.1 microseconds per centimeter.
40cm  = (duration/2) / 29.1;
41
42//Print distance
43Serial.print(cm);
44Serial.print("cm");
45Serial.println();
46
47if  (cm >= (3*height/4)) {
48    digitalWrite(firstLED, HIGH);
49    digitalWrite(secondLED,  LOW);
50    digitalWrite(thirdLED, LOW);
51    digitalWrite(fourthLED, LOW);
52  } 
53else if(cm >= (height/2)){
54    digitalWrite(firstLED, HIGH);
55    digitalWrite(secondLED,  HIGH);
56    digitalWrite(thirdLED, LOW);
57    digitalWrite(fourthLED, LOW);
58  }
59else if(cm >= (height/4)){
60    digitalWrite(firstLED, HIGH);
61    digitalWrite(secondLED,  HIGH);
62    digitalWrite(thirdLED, HIGH);
63    digitalWrite(fourthLED, LOW);
64  }
65else if(cm <= 10){
66    digitalWrite(firstLED, HIGH);
67    digitalWrite(secondLED,  HIGH);
68    digitalWrite(thirdLED, HIGH);
69    digitalWrite(fourthLED, HIGH);
70  }
71
72}

1int echoPin = 2;  //Define Echo pin
2int trigPin = 3;     // Define
3  Trig pin
4long  inches, duration, cm;   //Define variables
5int height=300;
6  //define depth of tank in cm
7int firstLED = 4; // define LEDs pin
8int secondLED
9  = 5;
10int thirdLED = 6;
11int fourthLED = 7;
12
13void setup() {
14
15Serial.begin
16  (9600);
17pinMode(trigPin, OUTPUT);  //Define output pin
18pinMode(firstLED, OUTPUT);
19pinMode(secondLED,
20  OUTPUT);
21pinMode(thirdLED, OUTPUT);
22pinMode(fourthLED, OUTPUT);
23pinMode(echoPin,
24  INPUT);  //Define input pin
25
26}
27
28
29void loop()
30{
31//Give a short
32  low pulse  to trigPin for ensure a clean high pulse
33digitalWrite(trigPin, LOW);
34delayMicroseconds(5);
35
36//give
37  high pulse to trigPin 10 microseconds
38digitalWrite(trigPin, HIGH);
39delayMicroseconds(10);
40
41digitalWrite(trigPin,
42  LOW);
43
44// Read the signal from the sensor
45duration = pulseIn(echoPin, HIGH);
46
47//
48  convert time into a distance
49// The speed of sound is 29.1 microseconds per centimeter.
50cm
51  = (duration/2) / 29.1;
52
53//Print distance
54Serial.print(cm);
55Serial.print("cm");
56Serial.println();
57
58if
59  (cm >= (3*height/4)) {
60    digitalWrite(firstLED, HIGH);
61    digitalWrite(secondLED,
62  LOW);
63    digitalWrite(thirdLED, LOW);
64    digitalWrite(fourthLED, LOW);
65
66  } 
67else if(cm >= (height/2)){
68    digitalWrite(firstLED, HIGH);
69    digitalWrite(secondLED,
70  HIGH);
71    digitalWrite(thirdLED, LOW);
72    digitalWrite(fourthLED, LOW);
73
74  }
75else if(cm >= (height/4)){
76    digitalWrite(firstLED, HIGH);
77    digitalWrite(secondLED,
78  HIGH);
79    digitalWrite(thirdLED, HIGH);
80    digitalWrite(fourthLED, LOW);
81
82  }
83else if(cm <= 10){
84    digitalWrite(firstLED, HIGH);
85    digitalWrite(secondLED,
86  HIGH);
87    digitalWrite(thirdLED, HIGH);
88    digitalWrite(fourthLED, HIGH);
89
90  }
91
92}