Low-cost Car Parking Sensor

1#include <Servo.h>
2
3Servo myservo;
4
5const int trigPin = 11;           //connects to the trigger pin on the distance sensor
6const int echoPin = 12;           //connects to the echo pin on the distance sensor
7
8const int redPin = 3;             //pin to control the red LED inside the RGB LED
9const int greenPin = 5;           //pin to control the green LED inside the RGB LED
10const int bluePin = 6;            //pin to control the blue LED inside the RGB LED
11
12const int buzzerPin = 8;         //pin that will drive the buzzer
13
14float distance = 0;               //stores the distance measured by the distance sensor
15
16const int switchPin = 7; // switch to turn sensor on and off
17
18
19void setup() {
20  pinMode(switchPin, INPUT_PULLUP);
21  Serial.begin (9600);        //set up a serial connection with the computer
22
23  pinMode(trigPin, OUTPUT);   //the trigger pin will output pulses of electricity
24  pinMode(echoPin, INPUT);    //the echo pin will measure the duration of pulses coming back from the distance sensor
25
26  //set the RGB LED pins to output
27  pinMode(redPin, OUTPUT);
28  pinMode(greenPin, OUTPUT);
29  pinMode(bluePin, OUTPUT);
30  pinMode(buzzerPin, OUTPUT);   //set the buzzer pin to output
31
32  myservo.attach(9);
33
34}
35
36void loop() {
37
38  if (digitalRead(7) == LOW) {
39  myservo.write(0);
40  delay(400);
41  distance = getDistance();   //variable to store the distance measured by the sensor
42
43  Serial.print(distance);     //print the distance that was measured
44  Serial.println(" in");      //print units after the distance
45
46  if (distance <= 20) {                       //if the object is close
47
48    //make the RGB LED red
49    analogWrite(redPin, 255);
50    analogWrite(greenPin, 0);
51    analogWrite(bluePin, 0);
52
53    tone(buzzerPin, 272);         //buzz the buzzer pin
54    delay(100);                   //wait 100 milliseconds
55
56    noTone(buzzerPin);            //turn the buzzer off
57    delay(100);                   //wait 100 milliseconds
58
59  } else if (20 < distance && distance < 30) { //if the object is a medium distance
60
61    //make the RGB LED yellow
62    analogWrite(redPin, 255);
63    analogWrite(greenPin, 50);
64    analogWrite(bluePin, 0);
65
66  } else if (30 < distance && distance < 40) {                                    //if the object is far away
67
68    //make the RGB LED green
69    analogWrite(redPin, 9);
70    analogWrite(greenPin, 255);
71    analogWrite(bluePin, 0);
72  } else {
73    //make the RGB LED blue
74    analogWrite(redPin, 0);
75    analogWrite(greenPin, 0);
76    analogWrite(bluePin, 255);
77  }
78
79  delay(50);      //delay 50ms between each reading
80  } else {
81    myservo.write(128);
82    analogWrite(redPin, 0);
83    analogWrite(greenPin, 0);
84    analogWrite(bluePin, 0);
85  }
86}
87
88//------------------FUNCTIONS-------------------------------
89
90//RETURNS THE DISTANCE MEASURED BY THE HC-SR04 DISTANCE SENSOR
91float getDistance()
92{
93  float echoTime;                   //variable to store the time it takes for a ping to bounce off an object
94  float calculatedDistance;         //variable to store the distance calculated from the echo time
95
96  //send out an ultrasonic pulse that's 10ms long
97  digitalWrite(trigPin, HIGH);
98  delayMicroseconds(10);
99  digitalWrite(trigPin, LOW);
100
101  echoTime = pulseIn(echoPin, HIGH);      //use the pulsein command to see how long it takes for the
102                                          //pulse to bounce back to the sensor
103
104  calculatedDistance = echoTime / 148.0;  //calculate the distance of the object that reflected the pulse (half the bounce time multiplied by the speed of sound)
105
106  return calculatedDistance;              //send back the distance that was calculated
107}