The light up tables that are seen sometimes at bars and other restaurants.
What it does
There is an array of 25 LED's that are multiplexed. Next to each LED there is a capacitive copper tape that will detect the cup when it is placed onto the surface of the plexiglass. The way the capacitive works is that there is one send wire for each capacitive component and then each LED gets one receive pin. In between there is a 2 Megaohm resistor that determines how far the signal goes so we needed that number resistor in order to see through the glass. The distance that the LED panel was placed about one inch below the plexiglass so the light is diffused to make the entire table light up.
How we built it
The wooden frame was made to fit the LED square. Then using a Dremel we cut a slot to fit the plexiglass into it. Then to fit the LEDS we drilled holes into a piece of MDF to evenly space the LED's. Placed next to each LED there is some copped tape that acts as the capacitive tiles. Then the Arduino DUE tells the LEDS to turn on based on if the capacitive signal is over a certain strength.
Challenges we ran into
Some of the challenges that we ran into is creating the capacitive elements. Each one needed to be wired to the same send pin. So to make it all work it quickly became a rats nest of wires and resistors, but after a lot of time all of the elements were wire up and ready to be connected to the copper elements. For some reason only on of the elements was not able to read but all 25 of the other ones worked perfectly. Another issue we ran into is the multiplexing of the LED's. At first we were using FASTled and that was working at first but as more and more was added to the code the LEDS were not writing properly. We moved to Neopixel and it worked better but because the LED's we are using are not neopixels more then one led turned on when we just wanted one to turn on.
Accomplishments that we're proud of
The accomplishments that we are proud of is actual making the table frame. Also making all the 25 capacitive elements work was a very large challenge so it was awesome when it started to work.
What we learned
Learned how to wire more the one capacitive element with one send pin. Multiplexing LED's.
What's next for The Tracer Table
We wish we had more time to make it actually work 100%. But with the time we were given we did not make it woke 100%. Next we want to spend more time to make it work really well. Then we want to make a bigger one.