Mixlar Mix

Open-source USB audio mixer and MIDI controller built on ESP32-S3.

What is Mixlar Mix?

Mixlar Mix is a desktop audio controller that combines 4 analog sliders, 6 programmable macro buttons, a rotary encoder, and a 480x320 touch display into a compact USB device. It connects to your PC over USB-C and lets you control per-app audio volumes, trigger macros, and display live system information.

Hardware

• MCU: ESP32-S3 (dual-core 240MHz, 8MB PSRAM)
• Display: 2.8" 320x240 IPS TFT (ILI9341) with capacitive touch (CST816S)
• ADC: ADS1015 12-bit I2C ADC (4 slider channels)
• Sliders: 4x 45mm linear potentiometers
• Buttons: 6x tactile switches
• Encoder: Rotary encoder with push button
• Connection: USB-C (TinyUSB composite: CDC + MIDI + MSC)
• Wireless: BLE 5.0 (UART + MIDI)

USB Device Info

Field	Value
VID	0x1209 (pid.codes)
PID	0x4D58
Product	Mixlar Mix
Manufacturer	MixlarLabs

Project Structure

firmware/          ESP32-S3 Arduino firmware
software/          Python desktop control software
hardware/          Schematic and PCB info
docs/              Documentation

Firmware

The firmware runs on ESP32-S3 with Arduino framework and uses:

• LVGL for the touch UI
• TinyUSB for composite USB (Serial CDC + MIDI + Mass Storage)
• Adafruit ADS1015 for 12-bit slider ADC
• BLE for wireless MIDI and serial

Building

1. Install Arduino IDE or Arduino CLI
2. Add ESP32 board support (Espressif ESP32 v3.0.0+)
3. Board settings:
   • Board: ESP32S3 Dev Module
   • USB Mode: USB-OTG (TinyUSB)
   • USB CDC On Boot: Enabled
   • PSRAM: OPI PSRAM
   • Flash Size: 16MB
4. Install libraries: Adafruit ADS1X15, LVGL, RotaryEncoder, TFT_eSPI
5. Open firmware/firmware.ino and upload

Software

Python desktop app that communicates with the Mixlar Mix over USB serial.

Installation

cd software
pip install -r requirements.txt
python mixlar.py

Features

• Per-app audio volume control (assign any app to any slider)
• Configurable macro buttons (media keys, keyboard shortcuts, launch apps)
• Encoder for master volume
• Simple JSON config (~/.mixlar/config.json)
• Auto-detect device on USB

Commands

python mixlar.py           # Connect and run
python mixlar.py setup     # Interactive setup wizard
python mixlar.py config    # Show current config
python mixlar.py list      # List active audio apps
python mixlar.py midi      # Switch device to MIDI mode
python mixlar.py pc        # Switch back to PC control mode
python mixlar.py preset    # List available presets
python mixlar.py preset streaming   # Load a preset

Config Example

Edit ~/.mixlar/config.json:

{
  "sliders": [
    {"app": "master", "label": "Master"},
    {"app": "spotify", "label": "Spotify"},
    {"app": "chrome", "label": "Chrome"},
    {"app": "discord", "label": "Discord"}
  ],
  "macros": [
    {"name": "Mute", "action": "mute_toggle"},
    {"name": "Play/Pause", "action": "media_playpause"},
    {"name": "Next Track", "action": "media_next"},
    {"name": "Prev Track", "action": "media_prev"},
    {"name": "Save", "action": "key:ctrl+s"},
    {"name": "Notepad", "action": "run:notepad.exe"}
  ]
}

Macro Action Types

Format	Example	What it does
Built-in	mute_toggle	System mute toggle
Built-in	media_playpause	Play/Pause media
Keyboard	key:ctrl+shift+s	Send keyboard shortcut
Launch	run:notepad.exe	Run a program

Presets

Presets are pre-made configs for common workflows. Load them with python mixlar.py preset <name>.

Preset	Sliders	Macros
music-production	Master, FL Studio, Ableton, Reference	Play, Record, Undo, Save, Metronome, Loop
streaming	Master, OBS, Discord, Game	Mute, Start Stream, Start Rec, Scene 1-3
gaming	Master, Discord, Music, Game	Mute, Deafen, Play/Pause, Next, Screenshot, PTT
video-editing	Master, Premiere, DaVinci, Music	Play, Cut, Undo, Redo, Render, Save

MIDI Mode

Switch to MIDI mode to use the device as a standard USB MIDI controller:

python mixlar.py midi      # Switch to MIDI mode

In MIDI mode:

• Sliders send CC 1-4 on channel 1
• Buttons send Notes 36-41 on channel 1
• Works with any DAW (Ableton, FL Studio, Logic, Reaper, etc.)

Configure MIDI mappings in config.json:

{
  "midi": {
    "slider_0_cc": 7,
    "slider_0_ch": 1,
    "slider_1_cc": 10,
    "button_0_note": 60
  }
}

Serial Protocol

The device communicates over USB CDC serial at 2,000,000 baud.

Commands (PC to Device)

Command	Description
PING	Keepalive check
READY	Handshake — PC software is ready
VOL,<idx>,<app>,<vol>	Set slider label and volume
MACRO,<idx>,<name>,<icon>	Set macro button label
ENTER_QA	Enter QA test mode
ENTER_STORAGE	Enter USB mass storage mode

Responses (Device to PC)

Response	Description
PONG	Reply to PING
STATE,CONNECTED	Device connected
SLIDER,<idx>,<value>	Slider moved (0-100)
MACRO,<idx>,PRESS	Macro button pressed
MACRO,<idx>,RELEASE	Macro button released
QA,PASS,<date>	QA test passed
QA,FAIL,<date>	QA test failed

License

MIT License. See LICENSE for details.

Links

• Website: mixlar.net
• Issues: GitHub Issues