The Wall Map, our final project is finally ready. In this post I am going to talk about some details about the piece in terms of physical computing. All the fabrication details can be found in this other post.
Also, some more detailed steps about the process can be found is this previous post.
The refugee crisis and terrorist attacks are some of the reasons that have influenced countries all around the world to build walls against their neighbors. The number of walls like these has increased dramatically over the past few years. We created wall installation that aims to create awareness about this topic and open a discussion to see if these measures are actually good or bad.
User is able to view the walls and borders that have been built since the 60’s until today and also the ones that are planned but not yet have been built using a control panel. Through another type of interaction, 2 users working together, literally standing side by side can trigger a projector that displays images of these borders on top of the map.
500 Mini LEDs placed on every border.
4 30×20 pieces of white acrylic (background)
2 30×20 pieces of black acrylic (countries)
1 Arduino Uno (microcontroler)
1 bench power supply
Adafruit 1.2in 7 segment digit number display
+ a lot of solder, wires and patience.
SENSORS AND TOOLS
1 potentiometer – choose the decade;
2 buttons – view the planned borders and view all the borders since the 60’s including the planned ones;
2 pressure sensors – working together that identify if 2 people are standing on them and trigger the projector.
Projection mapping – to identify the position of the map and display the images exactly in top of it.
Arduino & Processing – To use projection mapping and display images we decided to work with serial communication between Arduino and P5. In this case, Arduino reads if the pressure sensors are being triggered and sends that data to the processing sketch, that has all the images uploaded and a library that can map the area where things are going to be projected.
THE 500 LED’s
Each LED placed in the map needs 3V and 20ma to light up. So our first idea was to have all in parallel, divided per decade. But if we were to light everything up, we would need very high current (+/- 10 amps) and low voltage (3V). So we decided to balance that a little bit and putting the LEDs in groups of 4 or less in series and all these groups in parallel. By doing this we need 12V and 2.5 amps.
The reason we could not divide them all in groups of 4 is because there were some borders in which the number of LEDs was not a multiple of 4. So in these cases we had to use 3, 2 or even 1 LED. To balance the brightness we used different resistors with these LEDs:
This is how the back of the map looks, after placing all the LEDs: