In this Projecti will show how to make automatic coffee with android and arduino.

At the end of the tutorial you will have an android app working in bluetooth to make small/large coffee !

You can even send command by voice recognition !

Opening the Coffee Machine

Here we have the most complicated part i will advice you to check the doc of your machine.

For the one i use you just need to detach the bottom with something tiny like a screwdriver.

Soldering

Now that the machine is open we gonna solder 2 cable under each button and connect it to the relay.

If you use an old coffee with one button it's the same process just use one channel relay.

Arduino Side

In this part we see of to connect the bluetooth module with arduino and the relay

The connection between the relay and arduino are:

IN1: None

IN2: PIN 11 small coffee

IN3: PIN 10 turn on machine

IN4: PIN 9 Big coffee

Bluetooth:

VCC= 5v

GND=GND

TXD=RX

RXD=TX

The Code

The code is simple it initiate a bluetooth connection then

If you send value 1 you make small coffee, value 2 big cofee

When you upload the code disconnect the bluetooth (remove the 5v wire) otherwise you will get error

For some reason when I put HIGH it turn off the relay , so if you have problems just try to inverse HIGH and LOW.

then a button is pressed to make the coffee and the machine turn off

check the code comment

<p>char junk;<br>String inputString="";</p><p>void setup()                    // run once, when the sketch starts
{
 Serial.begin(9600);            // set the baud rate to 9600, same should be of your Serial Monitor
 pinMode(10, OUTPUT);
 digitalWrite(10,HIGH);
  pinMode(9, OUTPUT);
   digitalWrite(9,HIGH);
 pinMode(11, OUTPUT);
 digitalWrite(11,HIGH);
}</p><p>void loop()
{
 
  if(Serial.available()){
  while(Serial.available())
    {
      char inChar = (char)Serial.read(); //read the input
      inputString += inChar;        //make a string of the characters coming on serial
    }
    Serial.println(inputString);
    while (Serial.available() > 0)  
    { junk = Serial.read() ; }      // clear the serial buffer
    if(inputString == "1"){         //in case of '1'
            digitalWrite(10, LOW);    //turn on machine
      delay(500);
      digitalWrite(10, HIGH);
      delay(120000);                   //time to heat up 2mn (milli)
      digitalWrite(9, LOW);
      delay(500);
      digitalWrite(9, HIGH);           //big coffee
      delay(30000);                      //coffee comes out
      digitalWrite(10, LOW);        //turn off machine
      delay(500);
      digitalWrite(10, HIGH);  
    }else if(inputString == "2"){   //incase of '2'
      digitalWrite(10, LOW);          //turn on machine
      delay(500);
      digitalWrite(10, HIGH);
      delay(120000);                        //time to heat up 2mn (milli)
      digitalWrite(11, LOW);
      delay(500);
      digitalWrite(11, HIGH);          //small coffee
      delay(30000);                         //coffee comes out
      digitalWrite(10, LOW);           //turn off machine
      delay(500);
      digitalWrite(10, HIGH);
    }
    inputString = "";
  }
}

APP Inventor Android

In order to control our coffee machine with our phone, we will create an app with MIT app inventor .

Only requirement a gmail acoount.

You can upload my app and modify it in the app inventor it is very easy to use but i will advice to check some tutorial before.

I add voice recognition so if you say "coffee" it will give you a big coffee

To be able to install the app you have to go to your phone setting (in security) allow unknown sources.

Important :

To send value from the bluetooth i used the object "send text" so it will send the number 1 or 2.

You can also use the "send byte number" but it use ASCII so in order to send 1 to the arduino you need to send the value 49

Pay attention to the difference .