DIY Speedometer Using Arduino and Processing Android App

1/*Arduino Code for measuring speed of the Vechile using Hall Sensor
2
3  * Coded by Circuitdigest.com
4  * On 14-04-2017
5  */
6 /*CONNECTION DETIALS
7
8   * Arduino D11 -> RX of BT Module
9   * Arduino D12 -> Tx of BT
10   * Arduino
11  D2  -> Hall sensor 3rd pin
12   */
13#include <SoftwareSerial.h>// import the
14  serial library
15SoftwareSerial Cycle_BT(11, 12);  // RX, TX
16 int ledpin=13;
17  // led on D13 will show blink on / off
18 int BluetoothData; // the data given
19  from Computer
20float radius_of_wheel = 0.33;  //Measure the radius of your wheel
21  and enter it here
22 volatile byte rotation; // variale for interrupt fun must
23  be volatile
24 float timetaken,rpm,dtime;
25 int v;
26 unsigned long pevtime;
27void
28  setup()
29  {
30    Cycle_BT.begin(9600); //start the Bluetooth communication
31  at 9600 baudrate
32    //pinMode(ledpin,OUTPUT); //LED pin aoutput for debugging
33
34    attachInterrupt(0, magnet_detect, RISING); //secound pin of arduino used as
35  interrupt and magnet_detect will be called for each interrupt
36    rotation =
37  rpm = pevtime = 0; //Initialize all variable to zero
38  }
39 
40 void loop()
41
42  {
43   /*To drop to zero if vehicle stopped*/
44  if(millis()-dtime>1500) //no
45  magnet found for 1500ms
46  {
47   rpm= v = 0; // make rpm and velocity as zero
48
49   Cycle_BT.write(v);
50   dtime=millis();
51  }
52  v = radius_of_wheel * rpm
53  * 0.37699; //0.33 is the radius of the wheel in meter
54 }
55 
56 void magnet_detect()
57  //Called whenever a magnet is detected
58 {
59   rotation++;
60   dtime=millis();
61
62   if(rotation>=2)
63   {
64     timetaken = millis()-pevtime; //time in millisec
65  for two rotations
66     rpm=(1000/timetaken)*60;    //formulae to calculate rpm
67
68     pevtime = millis();
69     rotation=0;
70     Cycle_BT.write(v);
71     //Cycle_BT.println("Magnet
72  detected...."); //enable while testing the hardware
73   }
74 }

1/*Arduino Code for measuring speed of the Vechile using Hall Sensor
2  * Coded by Circuitdigest.com
3  * On 14-04-2017
4  */
5 /*CONNECTION DETIALS
6   * Arduino D11 -> RX of BT Module
7   * Arduino D12 -> Tx of BT
8   * Arduino  D2  -> Hall sensor 3rd pin
9   */
10#include <SoftwareSerial.h>// import the  serial library
11SoftwareSerial Cycle_BT(11, 12);  // RX, TX
12 int ledpin=13;  // led on D13 will show blink on / off
13 int BluetoothData; // the data given  from Computer
14float radius_of_wheel = 0.33;  //Measure the radius of your wheel  and enter it here
15 volatile byte rotation; // variale for interrupt fun must  be volatile
16 float timetaken,rpm,dtime;
17 int v;
18 unsigned long pevtime;
19void  setup()
20  {
21    Cycle_BT.begin(9600); //start the Bluetooth communication  at 9600 baudrate
22    //pinMode(ledpin,OUTPUT); //LED pin aoutput for debugging
23    attachInterrupt(0, magnet_detect, RISING); //secound pin of arduino used as  interrupt and magnet_detect will be called for each interrupt
24    rotation =  rpm = pevtime = 0; //Initialize all variable to zero
25  }
26 
27 void loop()
28  {
29   /*To drop to zero if vehicle stopped*/
30  if(millis()-dtime>1500) //no  magnet found for 1500ms
31  {
32   rpm= v = 0; // make rpm and velocity as zero
33   Cycle_BT.write(v);
34   dtime=millis();
35  }
36  v = radius_of_wheel * rpm  * 0.37699; //0.33 is the radius of the wheel in meter
37 }
38 
39 void magnet_detect()  //Called whenever a magnet is detected
40 {
41   rotation++;
42   dtime=millis();
43   if(rotation>=2)
44   {
45     timetaken = millis()-pevtime; //time in millisec  for two rotations
46     rpm=(1000/timetaken)*60;    //formulae to calculate rpm
47     pevtime = millis();
48     rotation=0;
49     Cycle_BT.write(v);
50     //Cycle_BT.println("Magnet  detected...."); //enable while testing the hardware
51   }
52 }