Card/Morse Code Reader

OBJECTIVE

This lab introduces us to two new sensors - the Photocell and the Force Sensor. We also learn how to use Processing to implement cross platform programs.

MATERIALS REQUIRED

PhotoCell, FSR sensor, Arduino Uno, LEDs, Connecting Wires, 10K Resistor

MECHANICAL: Using the FSR

Since the FSRs are not very accurate and are fairly noisy, they are better suited to applications requiring a binary (touched/not touched or squeezed/not squeezed) sensor. Cushions, soft toys etc are great for diffusing the force applied, while small plastic rods are good for localizing force (say,for use under a piano key).

FSR APPLICATION: Ergonomics

Ergonomics is becoming more and more important, and bad sitting postures are the cause of many back related health issues today. Two force sensors placed on a chair : one below the bottom cushioning, one behind the back cushioning, can help the situation. A warning message could be displayed on the computer screen/ using a speaker whenever the bottom sensor detects force (=> person is sitting) but the back sensor does not (=> person is hunched forward).

PROGRAMMING: Card Reader

This is a simple application of the photocell as a card reader. "Cards" are identified by their unique slit patterns. As the card slides, the photocell detects the presence of a slit. Using Processing, I display the pattern in real time on a screen. The screen can be reset at any time by hitting space. 

This display can also be used to read the Morse Code. One interesting thing to do would be to translate dots and dashes into English using a look-up table.

A quick video showing how this works is online at http://www.youtube.com/watch?v=Sa1s7ZE4a38