#electrical subsystem

PCB and Octagon Walls

PCB attachment is a big part of our design. To make exchanging LED panels easy while maintaining a strong electrical connection, we designed an attachment system which uses male and female header pins (male pins on the PCB and female pins on the walls) and nails to secure the panels to the walls. Two panels (which are treated as one panel) are attached to each of the four opposing walls in the octagon. 

Making LED Panels

Our original plan was to make our led panels out of protoboards, but we've decided to switch to PCBs for a few reasons:

Etching the protoboard is time consuming. (The first try took ~5 hours and even after deciding to using wires to jump the space instead of the pre-connected paths production of each board still took almost two hours)

One of our major goals is ease of use---if these boards break and need to be replaced, we want something that is easy to make. The Huang Lab at Olin (who are getting our culture keeper at the end of the semester) already has PCBs designed for this purpose, so we've altered our attachment design a bit to be more compatible with their equipment.

Building the LED Panel

Designing the Protoboards

Now that we have the basic software working, we need to focus on manufacturing our protoboards to place on each wall of our inner octagon. One of our primary goals is to make these LED panels easily removable, so we have decided to use header pins as both a method of sending signal to our LEDs and fixing the panels to our walls in an easily removable and robust fashion, but first we need to determine the best place put them. We also need to determine how we are going to attach header pins to our wooden walls and where wires will be fed through the wall so that any changes that need to be made can be added to the CAD before our final cut sheet is submitted to the machine shop.  

Software Integration

Controlling 4 Servos with a Button

Up until now, we've been focused on controlling out LEDs and haven't given much thought to the mechanical control portion of our software. We're starting to build our first prototype soon though, so we needed to put together a basic method for controlling our 4 servos in order to open and close the four segments of outer box as discussed in this post.

We've succeeded in opening and closing all 4 servos in the correct order at the push of a button (critically separate from the computer-controlled portion for ease of use). The video shown above is a demo of this system working.  

Because the lid fits together like a puzzle, the order in which all the servos open is crucial. We can toggle the time delay between each servo opening once we're able to test the servos on our particle board prototype. Unfortunately, there is still a bug with using the button. In order to close the lid, the user must press and hold the button rather than pushing it once, which is likely due to the fact that we used delays instead of using a counter. We will be able to fix this bug by implementing a counter in later iterations of the code. 

User Control of Intensities of Individual LEDs

Today we've finished our first major code deliverable for the project. We can now control four panels of light simultaneously and independently, which we do using a serial connection from python to the Arduino. 

Materials

This week we were able to acquire all of the materials needed for our first prototype. They are listed below:

protoboards (9)

LEDs (50)

9V Wall Power supply (1)

Arduino WiFi Shield  (1)