HERMES

HERMES (Hardware Environmental & Rotational Motion Evaluation Sensor)

HERMES is a USB-connected sensor board that reads motion, environmental, and GPS data and sends it to a computer in real time. The data is visualized in a browser dashboard that connects directly over Web Serial.

🛰️ Live dashboard: https://owenxman.github.io/HERMES/ Works in desktop Chrome and Edge. Use Demo data if you don't have hardware connected.

What this is

The board combines a 9-axis IMU, environmental sensor, and GPS module with an ATmega328 microcontroller. The microcontroller reads everything and streams it over USB serial to a computer.

The goal is simple: plug it in, open the dashboard, and see live motion + environmental data without any setup beyond a serial connection.

Hardware

Connection: USB-C (power + data), 8 MHz clock, ICSP header for programming.

Dashboard

The dashboard is a single index.html file. There is no backend, no build system, and nothing to install.

It reads serial data from the board and visualizes it in real time:

Everything runs in the browser. The board connects directly to your computer using Web Serial, and nothing gets uploaded anywhere.

How to run it

Locally

Open index.html in Chrome or Edge. Click Connect device, select the FT231XS serial port, and set the baud rate (default is 115200).

Browser support

Web Serial only works in Chromium-based browsers on desktop: Chrome, Edge, Brave, Opera.

Firefox, Safari, and mobile browsers will still load the page, but cannot connect to the board. Demo mode still works everywhere.

The web dashboard can be acessed at https://owenxman.github.io/HERMES/

Serial format

The board prints one line per update over serial. The dashboard tries to auto-detect the format. You can use any of:

JSON (recommended)

{"roll":2.1,"pitch":-5,"yaw":143,"ax":0.01,"ay":0.0,"az":1.0,"heading":143,"temp":22.4,"hum":41,"pres":1012.8,"gas":52000,"lat":44.47,"lon":-73.21,"alt":61,"sats":9}

key=value

roll=2.1 pitch=-5 yaw=143 ax=0.01 ay=0 az=1 temp=22.4 hum=41 pres=1012.8 gas=52000

CSV — first send a header line, then numeric rows:

roll,pitch,yaw,ax,ay,az,heading,temp,hum,pres,gas,lat,lon,alt,sats
2.1,-5,143,0.01,0,1,143,22.4,41,1012.8,52000,44.47,-73.21,61,9

Not all fields are required. You can start with just IMU data and add sensors later.

Fields

Orientation priority: quaternion → roll/pitch/yaw → gyro integration

Heading priority: heading → yaw → magnetic calculation (mx/my)

Repo structure

HERMES/
├── firmware/       # Microcontroller Code (not finished yet)
├── PCB/            # KiCad + PCB files
├── Production/     # Production Files
├── CAD/            # CAD Files for the Case
├── index.html      # Dashboard
├── LICENSE         # MIT License
└── README.md

Firmware

The firmware runs on an ATmega328 at 8 MHz. It reads:

• ICM-20948 over I²C
• BME680 over I²C
• GPS over UART (NMEA)

Then it prints telemetry over USB serial in one of the supported formats.

This section will get updated once the final firmware is cleaned up and documented.

License

Released under the MIT License — you're free to use, copy, modify, and distribute this project, including commercially, as long as the copyright notice and license text are included. See the LICENSE file for the full terms.