The Bright Light Touchpad is a capacitive enabled touchpad and LED matrix designed for large scale applications. Originally modeled after the dimensions of a Dance Dance Revolution dance pad, the Bright Light Touchpad can be used as a game controller and so much more. Measuring 30" by 30", the matrix has room for a 12 by 12 array of LEDs, and a grid of 11 by 11 sensing points. It uses the C2000 Launchpad to control the LEDs and measure the capacitive sensing.
HOW IT WORKS
To control the LEDs, we used TI's part TLC5940. These LED drivers can be daisy chained for the desired number of LEDs. They are communicated to using the SPI communication protocol. The capacitive sensing is controlled by the digital I/O and the ADC of the C2000. 11 driving electrodes and 11 sensing electrodes are wired between the LEDs of the matrix, creating 121 intersections. At these intersections, a capacitor was created using a sticker in between pieces of aluminum foil. A signal sent by the digital I/O is measured by the ADC of the C2000. The capacitance of the intersection determines how much power of the high frequency signal passes though. When a conductor such as a finger or a foot comes into the vicinity of the intersection, the capacitance changes. This changes the amount of power of the signal as measured by the ADC. This change in measurement is used to sense touch.
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6740.intern design 2013.zip
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