The Problem with Current Assistive Tech

Assistive technology is essential, but it is frequently locked behind proprietary ecosystems and massive price tags. For users with severe motor disabilities or paralysis, gaining basic access to a computer shouldn't cost thousands of dollars.

L.I.P.S. (Linear Interface for Paralysis Support) is designed to solve this by providing a fully open-source, highly customizable sip-and-puff mouse alternative. It costs a fraction of commercial solutions to build, requires absolutely no proprietary software, and works instantly on any modern operating system.

How It Works

The device reads breath pressure through a food-grade silicone mouthpiece, mapping "sip" and "puff" gestures to configurable actions (like left-click, right-click, scrolling or a keyboard macro). Simultaneously, an integrated 2-axis hall effect analog joystick allows the user to control the mouse cursor using lip or chin movement.

It enumerates as a composite USB HID Keyboard + HID Mouse + CDC Serial device. Because it acts as a standard USB mouse and keyboard at the hardware level, it is entirely plug-and-play.

Hardware Architecture

The core of the system is designed around accessible, low-cost components:

  • Microcontroller (CH552G): Chosen for its native full-speed USB engine. It runs an 8051 core at 24 MHz and has enough ADC channels for our sensors, all in a friendly SOP-16 package. It runs off the 5V USB rail (stepped down to 3.3V internally).
  • Pressure Sensor (XGZP Series): We use a differential pressure sensor to measure the breath input. The firmware auto-baselines the sensor on every single boot, meaning the user never has to manually zero the device.
  • Analog Joystick: A standard 2-axis hall effect or potentiometer joystick powered from the CH552's 3.3V rail. The center position is calibrated automatically on startup and saved to the CH552's internal EEPROM.
  • Custom PCB: The electronics are housed on a custom 2-layer board. The board is optimized for easy surface-mount assembly with castellated holes and an integrated USB-C connector (with 5.1 kΩ pull-downs for standard cable compatibility).

Firmware & Web Configurator

Instead of forcing users to re-compile Arduino code just to change their mouse sensitivity or swap their click actions, L.I.P.S. utilizes the Web Serial API.

By navigating to the

  • official L.I.P.S. website using a Chrome or Edge browser, users can connect directly to the device's CDC Serial channel. Through a custom command protocol, they can seamlessly map new actions to their sips and puffs, adjust scroll speeds, and even flash firmware updates directly from the browser. All settings are saved to the EEPROM so they persist across power cycles.

    Fully Open Source

    Everything you need to build, modify, or manufacture this device is available under the CC BY-NC-SA 4.0 license.

    • Firmware: Written via the CH55xDuino framework.
    • Hardware: KiCad schematics, gerbers, and interactive BOMs.
    • Enclosure: 3D-printable STLs (optimized for PLA or Resin) for the head, top lid, and bottom lid.