Do It Yourself low cost QR-code scanner

Posted on September 29, 2009

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For the CabFab Business Event we (The RoomWare Projectsee manifesto) have been prototyping a working solution to scan the QR-codes on the name tag. This blog post documents the main elements.

Experience

During the event we had the chance to test the first prototype of the reader. The results will be used for a new version of the reader that will be deployed at the NPOX festival (which will host 1003 professionals from the Dutch public broadcasting companies) in september.

Why QR-codes?

RFID would be a nice and technological better choice for festivals. However they add an extra set of actions to the preparation process of an event. Each RFID-card has to be registered manually to a visitor and bundled with the name tag.  Although QR-codes are “slower” in reading and less reliable (a bad printed or damaged QR-code will not work) they are easier to produce, as they can be automatically generated and included in the mail-merge used to produce the badges.

Basic setup of the application:

Picture 30

  1. the QR-code is printed on passes.
  2. It is read by a Web cam (Logitech QuickCam in my case).
  3. The camera image is processed by a QR-code reader implemented in Flash
  4. The info on the card is displayed on screen and used to send an e-mail via a Web Server when two people are detected in the same session.

The advertisement in the venue

Picture 37

It reads: “Why is this on your name badge?”
Do you want to know? Go to the central hall and look for the CABFAB Connection points
“Follow these arrows”

The application

Picture 31

  1. The application waits for two people to show their QR-code
  2. When two people (“David” and “John”) are registered, a mail is sent to both, containing the contact data embedded in the QR-code.
  3. When a new name / QR-code is presented, the display is reset and new connections can be setup.
  4. The system resets automatically after N seconds. (Set to 10 seconds for this installation) so if connecting to the second person fails, the screen is reset as well. The 10 seconds provide enough time for the second person to get registered by the reader.

The reader / scanner: first prototype

Picture 26

The reader consists of the following items:

  1. The web cam
  2. A “statif”
  3. The “table” on which people can put their QR-code
  4. A “slot” to position the card with the QR-code underneath the camera

As you can see i used the box in which the web cam was sold. The slot is made by using the cartboard holding the camera in the box and cutting out the shape of the card and the camera statif.

The “statif” is the clip already attached to the camera. Fold it open, turn the camera around so it faces “backwards” and paste it to the lid of the box with tape.

Picture 35

Like this.

Picture 34

This photo shows all parts: web cam, box and slot to fit the card with QR-code in. The wide cut-out on the left hand side is where you slide the card with QR-code in. It is made from the cart board that holds the camera in the box.

Ajusting the camera

The QR-code can currently not be read by the Flash Client when placed under and angle. So the camera has to be set properly by hand. A little error margin is allowed. How:

  1. Pick up the box with the camera already in place
  2. Look at it from the side and the front and tilt the camera head until the lens is approximately in a 90 degrees angle with the surface it looks at.
  3. Test it with the QR-code reader application

Picture 27

In this image the camera is still a bit tilted too much to the right hand side.

Total cost of the scanner: 14 euro and approximately 30 minutes to build and adjust.

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