Midi controller

MIDI Studio - Hardware Design

Open-source hardware design files for the MIDI Studio controller.

Teensy 4.1 based MIDI controller with ILI9341 display, 10 rotary encoders, and 15 buttons.

Hardware Specifications

Core Components

• MCU: Teensy 4.1 (ARM Cortex-M7; hardware rated up to 600 MHz, with MIDI Studio firmware configured at 450 MHz)
• RAM: 8 MB PSRAM (mandatory - soldered on underside pads)
• Display: ILI9341 2.8" TFT (320x240, SPI)
• Encoders:
  • 8x Bourns PEC11R rotary encoders (24 PPR, smooth, with push button)
  • 1x Bourns PEC11R rotary encoder (24 PPR, detented, with push button)
  • 1x E38S6G5 optical encoder (600 PPR, high-resolution)
• Button inputs: 15 total (6x panel tactile switches + 8x macro-encoder push switches through the multiplexer, plus the NAV encoder push directly on MCU pin 32)
• Multiplexer: CD74HC4067 (16-channel analog multiplexer; 14 button inputs used)
• Connectivity: USB MIDI (USB-B connector)

Display Interface (SPI)

• CS = Pin 28
• DC = Pin 0
• RST = Pin 29
• MOSI = Pin 26
• SCK = Pin 27
• MISO = Pin 1
• Firmware-configured SPI speed: 50 MHz

Power

• USB-powered (5V)
• Teensy 4.1 regulates to 3.3V for peripherals

Repository Contents

pcb/

KiCad PCB design files and manufacturing outputs.

pcb/kicad/
midi-studio.kicad_pro      # KiCad project
midi-studio.kicad_sch      # Schematic
midi-studio.kicad_pcb      # PCB layout
midi-studio.step           # 3D model
gerbers/                   # Gerber files for PCB fabrication
bom/                       # Bill of Materials + CPL
pdf/                       # Schematic and assembly drawings (PDF)

PCB Specifications:

• Layers: 2-layer PCB
• Thickness: 1.6mm
• Surface finish: HASL or ENIG
• Compatible: JLCPCB, PCBWay, OSH Park

cnc/

CNC machining files for enclosure fabrication (G-code, DXF).

keyshot/

Photorealistic renders for documentation and marketing.

Software Tools

This project was designed using the following software:

• KiCad (latest stable version) - PCB schematic and layout design
• Aspire 12.5 - CNC toolpath generation and G-code export
• OnShape - 3D mechanical enclosure design
• KeyShot - Photorealistic rendering

All design files are provided in their native formats as well as exported to common interchange formats (PDF, STEP, DXF, Gerber) for maximum compatibility.

3D Model (OnShape)

Public OnShape CAD Model:

https://cad.onshape.com/documents/a6b73f1c7a20e07680bfab81

Includes:

• Complete enclosure design
• Mounting holes for all components
• Panel cutouts
• Export-ready for 3D printing or CNC

Bill of Materials (BOM)

Electronic Components

Estimated Cost: ~€80-100 (excluding enclosure)

Manufacturing

PCB Fabrication

Recommended: JLCPCB

Gerber Files: pcb/kicad/gerbers/

CNC Machining

Materials:

• Front panel: Plywood 5mm + 2 thin wood layers 0.6mm
• Bottom panel: Plywood 5mm
• Enclosure: Birch plywood 12mm

Assembly Guide

1. PCB Assembly - Solder components, install Teensy 4.1 (verify PSRAM!)
2. Enclosure Prep - CNC mill or 3D print parts
3. Final Assembly - Mount display, encoders, buttons, PCB
4. Testing - Flash firmware, test all inputs

Detailed assembly instructions: See wiki (coming soon)

Related Repositories

• Core Firmware - Teensy 4.1 firmware
• Bitwig Plugin - Bitwig Studio extension

License

Licensed under CERN Open Hardware Licence Version 2 - Strongly Reciprocal (CERN-OHL-S-2.0).

What This Means

✓ You MAY:

• Manufacture for personal use
• Modify and improve the design
• Share modifications (same license)

⚠ You MUST (if commercial):

• Publish all modifications
• Keep the same license
• Provide attribution

✗ You MAY NOT:

• Sell without publishing design files

See LICENSE for full terms.

Important Notes

PSRAM is Mandatory

⚠ Teensy 4.1 MUST have 8MB PSRAM soldered on underside pads.

Without PSRAM, firmware will NOT run.

Purchase: https://www.pjrc.com/store/psram.html

Support

Issues: GitHub Issues

Commercial Licensing: contact@petitechose.audio

Built by petitechose.audio