Creative Technologies > Block 3 > Projects > Cookie monster

Cookie monster

We found out someone is eating the cookies from the jar in the kitchen! We thought about it and came to the conclusion that the best thing to do would be to prepare a trap to find out who was eating them. Let us build something that will take a picture of whoever opens the cookie jar. No cookie monsters were hurt in the making of this experiment.

Materials

  • 1 Arduino Uno board
  • 1 Education Shield
  • 1 breadboard
  • 1 web camera
  • 1 TinkerKit ultra bright white LED
  • 1 1M ohm resistor
  • 1 TinkerKit wire
  • 3 colored jumper wires (one long)
  • Cookie Monster kit
  • Aluminum foil
  • 1 conductive cookie jar
  • 3-4 rubber bands

Instructions

  1. Attach the shield onto the top of the Arduino board.
  2. Connect the TinkerKit LED to D9.
  3. Using a separate breadboard, connect a 1M ohm resistor between digital pin 3 and digital pin 2.
  4. Make a capacitive sensor by cutting a 20cm x 20cm square of aluminum foil. Wrap one corner of a foil square to a loose jumper wire – the metal part must contact the foil.
  5. Connect the loose jumper wire to digital pin 3, through the breadboard.
  6. Build the Cookie Monster.
  10. Place the web camera inside the head of Cookie Monster and place the TinkerKit LED into the mouth.
  12. Place your Arduino inside the monster’s body. Place the capacitive sensor in front of the Cookie Monster. Place the cookie jar on the capacitive sensor, making sure the metal parts are in contact.
  13. Connect the Arduino assembly to your computer and uload the example CookieMonster.
  14. Open and run the CookieMonster processing sketch.

Code

Find the code in File>Examples>EducationShield>Block3-Magic>Projects>CookieMonster



Find the Processing code for capturing webcam images of your cookie thief in File>Examples>EducationShield>Block3-Magic>Projects>CookieMonster>Processing>CookieMonster




How it works


When you touch the cookie jar, the capacitive sensor is activated and Arduino sends a “p” character to Processing through the serial port. When the Processing sketch receives this character, it takes a picture using the webcam.


Arduino


    

  • The EducationShield and CapacitiveSensor libraries are included.
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  • The CapacitiveSwitch object, sensor is declared.
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  • The variable led is declared.
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  • In setup(), serial communication is initialized.
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  • The capacitive sensor is configured and initialized.
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  • The led pin is set as an output.
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  • In loop(), if the capacitive sensor is pressed, that is touched, the LED is turned on and ‘p’ is printed to the serial port.
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  • The program pauses for 2000 milliseconds.
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  • If the sensor is not pressed, nothing happens.
    • 



Processing


    

  • The processing video and serial libraries are included.
    • 

  • The camera and serial port objects are declared.
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  • In setup(), the window size is set to 640 x 480 pixels, and the renderer P2D is chosen.
    • 

  • The camera and serial port are configured and initialized.
    • 

  • In draw(), if the camera is available, the camera image is read.
    • 

  • The image read from the camera is drawn to the program window.
    • 

  • The String variable timeStamp is declared to hold current date and time.
    • 

  • The text timeStamp is drawn in coordinates (10, height-10).
    • 

  • If the key ‘p’ or ‘P’ is pressed the current image is saved to the sketch’s data folder.
    • 

  • If the serial port is available, the incoming data is read and stored in inByte.
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  • If inByte is equal to ‘p’, the current image is saved to the sketch’s data folder.
    • 



Troubleshooting


    

  • Refer to the illustration and double check your connections. Make sure the shield and jumper wires are firmly connected.
    • 

  • If Processing is reporting error and no image is showing up, make sure you have the latest version of Processing, and:

      

    • Arduino is connected to the computer, and in myPort = new Serial(this, Serial.list()[0], 9600) is using the serial port number of your Arduino board. Find it in Tools>Serial Port in the Arduino IDE.
      • 

    • initializeCamera() is using the correct camera number from the list printed out by Processing.
      • 

    

    • 

  • If you are touching the cookie jar and no image is captured, try touching the capacitive sensor directly. If it is working, you need a more conductive cookie jar. If not, see the capacitive sensor reference for debugging.

    

    • 

  • If you can not find the picture of cookie thief, look into the CookieMonster sketch folder of Processing for it.
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Learn by doing


    

  • Change the reaction time: make the monster wait for a few seconds before taking the picture, so you catch the thief with cookie in hand!
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  • Record a monster sound according to these instructions, and use an 8 ohm speaker to play the sound when the capacitive sensor is triggered.
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