This iteration of the “PipKey” MIDI instrument largely takes inspiration from concertinas and aims to improve the ideas discovered after “finishing” the v2. The PipKey v3 is designed to wirelessly connect to MIDI sequencing software and have several different operating modes to play in various scales, linearly (like a piano), or by position (like a stringed instrument). The combination rotary switch and scissor-lift/pantograph-esque mechanism in the center allows the instrument to rotate and expand/contract for better control of MIDI note velocity/pitch-bending as well as emulate switching between strings on, say, a cello/guitar.

Essentially, v3 is supposed to take the Wii Nunchuck's analog bindings from v2 and make them digital/ergonomic, and therefore faster/easier to activate simultaneously. The addition of the rotary switch and scissor lift provides more options for controlling more operating modes in unique ways. It also works well with the two-handed form factor and adds a fun level of uniqueness that I would not have gotten from ten buttons on a flat surface.

Given the two joysticks and assortment of buttons, this symmetric design could straight-up work as a weird video game controller. Although it would lack access to a full controller's key bindings. Plus, it would take quite a bit of finicking to get used to. Those PSP joysticks aren't anything to write home about either.

You might've noticed that this page doesn't include any downloadable code. Thing is, I was going to actually program the microcontrollers and get the device “fully functional", but I ran into some major design flaws and wiring/power issues that made it difficult to transition to that final phase of the project. If I were going to provide code, I'd want it to work well and showcase as much of the device as possible, but given current design flaws, that's just not possible.

Design Flaws: • The rat's nest of solid core wire is bad for self-explanatory reasons. Using hand-soldered perfboard instead of a half-breadboard (as used in the first checkpoint of v3 and previous PipKey designs) does save a considerable amount of room/weight, but it's a rather permanent solution that takes time to create and is a pain to edit/reproduce. • The 45mm linear slide potentiometer should be attached closer to the right-hand structure so that its wires don't have to move as the scissor lift moves. *Wired UART communication between the two microcontrollers sounds like a good way to simplify communication and free up SPI for the nRF52 chip, but the wires totally get in the way of the rotary switch's movement. It's also another four physical connections that take up space. I'll probably have to go back to an early revision of the design that was going to use nRF24 modules to wirelessly communicate between both hands. • Powering the Itsy Bitsy from the Feather with a one small lithium-ion battery for everything (including the small OLED screen) doesn't work as was ambitiously hypothesized. Independent power sources for each device (coupled with close-range wireless communication) seems like a more realistic choice for supplying power. • There's an open blank space on the front of the right-hand structure that needs to be filled with something. • The scissor lift mechanism could be smoother and smaller (the smallest binding screws I could find were M5). Perhaps adding a small spring would create some nice physical feedback. • I have no clue what to use the left-hand joystick for. It's basically there out of fear that I'll want to switch to a design that uses the right-hand for the primary notes instead. That, and it also makes the PipKey capable of acting like a video game controller.

Printing Notes: • 0.2mm Layer Height for all parts • Most parts are designed to be printable without supports. Obvious exceptions include the main hand structures' massive overhangs and lower button indents which need standard supports. Also, use tree supports for the tiny center nut overhang in the Scissor Lift Axel.

Materials: • PLA • Adafruit Feather 32U4 nRF52 Bluefruit • Adafruit 3.3v Itsy Bitsy • Solid Core Wire • Standard Breadboard Jumper Wires • Female Headers • Perfboard • Breadboard-esque Perfboard • Various M2 Screws and Nuts • Various M3 Screws and Nuts • M5 Binding Screws • Kalih Choc Red Low-profile switches • PSP Joysticks • B3200-42 Rotary Switch • Digispark OLED 128x64 SSD1306 • Lithium Ion Battery (500mAH) • Universal Camera Wrist Straps • Small switches (SS12F15-G5) • 45mm Linear Slide Potentiometer

Contact me if you have any questions!