Sharps and Jordan designed Mega PocketC.H.I.P. to be a 7’5″ tall working replica of PocketC.H.I.P.. This mega device not only had to look and operate exactly like PocketC.H.I.P., but also had to be entirely powered by C.H.I.P.! And just like Mega C.H.I.P. before it, all of the Mega PocketC.H.I.P. design files had to be open source.
Early frame prototypes were draw out on paper and whiteboard until a simple-to-assemble and built-like-a-tank design was achieved. We joked that Mega PocketC.H.I.P. had to survive hordes of children mashing buttons for three days straight –and, no joke, that’s exactly what it was up against.
With every angle and plane measured of PocketC.H.I.P., Sharps and Jordan had to settle on a scale for Mega PocketC.H.I.P.. From the outset, Dave wanted Mega PocketC.H.I.P. to be taller than him. His towering 6’5″ height, available arcade buttons, TV costs, and standard sheet material sizes were all factors determining the final Mega PocketC.H.I.P. scale.
An early draft called for using only one sheet of material for the entire surface of Mega PocketC.H.I.P.. This approach is similar to how PocketC.H.I.P. is a single printed circuit board. However, using one single 4′ wide sheet of material would not make Mega PocketC.H.I.P. tall enough. Instead, we used two sheets of 5′ wide material, which allowed us to create a Mega PocketC.H.I.P. with enough height to tower over Dave.
Luckily the scale created by using two 5′ wide sheets worked well with the 100mm arcade buttons that we wanted to use, and made it fairly easy to source a TV with appropriate dimensions. Once the height and width were finalized the Mega PocketC.H.I.P. to PocketC.H.I.P. scale was set at approximately 13.6:1.
With two weeks until Maker Faire we were fairly confident with the design, we just had to build it.
A Two Week Build Sprint
Constructing Mega PocketC.H.I.P. took every moment of the remaining two weeks. Sharps and Jordan led the charge assembling the frame and keyboard, with help from Jerrick. Jordan wired the keyboard with electronics help from Jose and Langley.
The build was a team effort!
Crunch, Jose, Langley, Alex, and Tony created a scaled-up version PICO-8 to meet the newly available screen realestate output from the HDMI DIP, and wrote a program to parse button input from the mega keyboard.
Mega Frame Assembly
Since we wanted the mega pieces to be perfect, and to make assembly faster, we contracted out CNC machines to quickly fabricate the wooden keyboard frame, the white PVC front, all the vinyl graphics and lettering, and metal welded A-frame.
Once all the these pieces were delivered, we assembled the plywood and steel tubing that make up the main A-frame structure of Mega PocketC.H.I.P.. The white PVC exterior, arcade buttons, wiring, and the jumbo 65″ TV all were added shortly thereafter.
In the first version of the wiring, we used fancy snap-tight terminals for every place a wire connected with a button. This worked and looked tidy, but we had doubts about the connectors withstanding the heavy use during the faire.
Not willing to take any chances, we completely rewired the keyboard the night before loading it onto a faire-bound truck. The time, we used good old solder to guarantee a reliable, durable connection. It was all hands at the soldering stations for this late night sprint.
Mega Keyboard Software
The keyboard software runs on the Teensy and continuously scans for simultaneous row and column input. Since no two keys have the same row and column combination, you can determine exactly what key was pressed by reading the two values. This keyboard matrix design is a commonly used solution when you need to build a custom keyboard.
Adding lettering and artwork to Mega PocketC.H.I.P. required scaling up the silkscreen files we use for PocketC.H.I.P. and used a vinyl printer to cut everything out.
To help precisely place the lettering we pointed a projector showing the desired keyboard layout and aimed it at the blank PVC. With a steady hand and careful eye the lettering was applied without too much hassle, and the mega replica was complete.
Booth Tested, Maker Faire Approved!
Mega PocketC.H.I.P. withstood three days of intense button mashing and looks nearly as good as when we first unveiled it. All the hard work paid off. We’ve reassembled Mega PocketC.H.I.P. back in the office right next to Mega C.H.I.P. and use it for PICO-8 gaming breaks –especially Crunch Ball.