Arduino/iOS – Bike speedometer tracking using bluetooth

Scope of the project,
add a speedometer on my MTB to store and track the trip using only Bluetooth transmission, send data to iPhone and store to cloud for later data-analysis.

Used components:

  • digital display (controlled by the iOS app). Can show current speed (km/h), total km, current temperature, current humidity.
  • GPS module
  • bluetooth module
  • DHT sensor for temperature and humidity
  • Swift backend
  • mongoDB as database
  • Swift iOS App

Read More


Arduino – Room Spy Email Notificator

Hi nerdz,
today i’ll show you how to easily control remotely your room with a stupid motion detector, a piro sensor (or you can use other sensors, like ultrasonicinfraredlight sensorpressure, etc etc…) and two lines of PHP code and C.

* Useful if you want to know if anyone enter in your room and the time that remains there! *

You can get this sensor from AirWick deo! 😎

How it works?

Your piro sensor, when detect a motion, notify arduino, that was programmed to send to serial port a value (“m” or “n”).
These value are interpreted by a serial reader (c# program, objective-c, java, c++, or somethig else) that call a PHP page that send email if is enabled sending mode.
Second php page, permit you to control arduino (enable/disable/show logs/clear all).


Connect your piro sensor to arduino, easy way, like this:

After that, write your simple arduino code:

 * Room Spy with Piro sensor
 * (c)2012 - Alberto Pasca
int inputPin = 2;    // choose the input pin (for PIR sensor)
int pirState = LOW;  // we start, assuming no motion detected
int val = 0;         // variable for reading the pin status
void setup() {
  pinMode(inputPin, INPUT);     // declare sensor as input
void loop(){
  val = digitalRead(inputPin);  // read input value
  if (val == HIGH) {            // check if the input is HIGH
    if (pirState == LOW) {      // MOTION START
      pirState = HIGH;
  } else {
    if (pirState == HIGH) {     // MOTION STOP
      pirState = LOW;

Well, test your code, Arduino can able to send to serial “m” or “n”. If do this, you’re ok!

Now write a serial reader (read these (p1 || p2) old post to know how) and call your php page.
Here C# snippet:

try {
  SerialPort port = new SerialPort( "COM9", 9600, Parity.None, 8, StopBits.One );
  string data = string.empty;
  while ( true ) {
    data = port.ReadLine();
} catch ( Exception ee ) { Console.WriteLine( ee.Message ); }

My Serial Reader, write this output (“ok” or “ko”, based on php output):

Now, i create a control page, that do this simple things.
If enable, write to roomcmd.dat “1″ value, else write “0″. Log and Clear read or clean log file.

if ( $_POST["mode"] == "enable" ) {
    $flog = fopen("roomcmd.dat", "w+"); 
    fwrite($flog, "1");
} else if ( $_POST["mode"] == "disable" ) {
    $flog = fopen("roomcmd.dat", "w+"); 
    fwrite($flog, "0");
} else if ( $_POST["mode"] == "log" ) {
    $msg = file_get_contents("roomspy.txt");
} else if ( $_POST["mode"] == "clear" ) {
    $flog = fopen("roomspy.txt", "w+"); 
    fwrite($flog, "");

Last step, is the “mail script” (called from SerialReader), that read values from file “roomcmd.dat” that can contains “0″ or “1″. Decide to send or not notifications.

  $enable = file_get_contents("roomcmd.dat");
  if ( $enable == "1" )
     $now = date("d-m-o h:i:sA");
     $msg = "[Arduino :: $now]\n";

     $flog = fopen("roomspy.txt", "a+"); 
     fwrite($flog, $msg);

          "[Arduino] - Something in the way...", 
   echo "ok";
  else echo "ko";

With these two pages, you can able to control your Serial Reader program, that is connected to Arduino and send or not email to your address.

Final circuit with piro sensor connected:

You can use a Wifi Shield or Ethernet Shield or GSM/GPRS Shield to send email.
In this example you need a powered pc connected to Arduino.

In next tutorial, we attach it on a GSM/GPRS Shield.

enjoy as usual!