PipKey v4 BLE MIDI Instrument

At long last, the PipKey is in a functional and satisfactory state! This 3D-printed, ESP32-based, battery-powered Bluetooth Low Energy MIDI instrument uses a combination of buttons, joysticks, and a spring-loaded rotating scissor lift mechanism to play music in a variety of interesting ways. Check out the following YouTube video for a quick demo!

You can also see the PipKey v4 working as a video game controller in the following demo:

In Version 4, I’ve leaned harder into the concertina/accordion inspiration started in Version 3, with a five-position rotatory position switch setup and a slide potentiometer for tracking the distance that the PipKey is pulled. The rotating positions can be used for actions like swapping between strings, octaves, or types of chords. The scissor lift assembly can be pulled to add vibrato effects to notes, as well as perform different notes in the same motion/style of an accordion/concertina/squeeze-box.

Since ESP32 microcontrollers have difficulty using both ESPNOW and BLE at the same time, two nRF24 controllers were required for wireless communication between both halves. The type of ESP32 that I’m using comes with a built-in Li-Po battery charger, which simplifies the circuitry a decent bit. The use of M3 binding screws (aka Chicago screws) as opposed to M5 screws in Version 3 allows for a denser amount of movement in the scissor lift.

Printing, Assembly, & Coding Instructions:

I haven't included anything here because it would take a long time to write/photograph/document the full process and I’m unsure of any genuine interest in others recreating this project. Plus, I’m working full-time these days.

In order to maintain some form of protection over the project I've spent years progressively developing, I‘ve neglected to include the code that powers both halves of the device.

If you are genuinely interested in building one of your own, please reach out to me.

Materials:

• PLA/PETG

• 2x ESP32 WeMos LOLIN32 (Soldered with upward-facing Female Headers)

• 10x Choc Kalih Low-Profile Keys

• 2x PSP Joysticks 2x 1000mAh (Liter energybattery)

• 2x 2-pin JST Battery connector wires

• 2x Monochrome 128x32

• 2x Camera Straps ("SmallRig Camera Cage Wrist Strap”)

• 4x Switches (SS12F15-G5)

• Various M2 & M3 Screws and Nuts

• Various M3 Chicago Screws (For scissors lift assembly)

• 1x Spring (9.5x16mm Compression)

• 2x Spring (8x28.5+mm Extension)

• 1x 45mm Linear Slide Potentiometer

• 2x Microswitches

• 2x nRF24

• 2x8cm Protoboard Female-to-Male Jumper Wires

• Female Header Pins (Various Lengths)

• Solid-core wire (Various colors)

• 2x 10uF Cap (for nRF24)

• A bit of tape

• Android Phone with Fluidsynth