TinyMocap - Romaric SICHLER

Hardware and firmware for the RSbracelet, a tiny motion capture device based on the M5StickC Plus2. Allows to send IMU data over Wi‑Fi with OSC, and control an addressable LED bracelet with ArtNet.

Install from browser

Connect the M5StickC Plus2 to your computer with a USB cable, then use the button below. The installer works best in Chrome or Edge on desktop.

Your browser does not support Web Serial. Please use Chrome or Edge on desktop. Installation requires a secure HTTPS page.

Firmware file location: firmware/rsbracelet-m5stickcplus2-v0.1.0.bin

First Wi‑Fi setup

Power on the M5StickC Plus2.
Go to the Wi‑Fi screen.
Long press the main button to start Wi‑Fi configuration mode.
Connect your computer or phone to the access point RSbracelet-XX.
Open the IP address shown on the device screen in your browser.
Select your Wi‑Fi network, enter the password, and submit the form. (WPA2 was the only tested standard)
The device saves the credentials and restarts.

Device screens

A short press on the main button cycles through five screens:

Wi‑Fi: shows the connected network and local IP address.
IMU: shows filtered accelerometer and gyroscope values.
Bracelet: shows a 32‑pixel preview grid.
OSC: shows OSC status, destination IP, port, and frequency.
Lock: long press turns off the display.

IMU and filtering

At startup, the firmware calibrates the gyroscope. Keep the device still during this step. The accelerometer and gyroscope values are then smoothed with low-pass filters before being displayed or sent over OSC.

The exposed values are:

ax, ay, az: accelerometer values
gx, gy, gz: gyroscope values with offset correction

Web dashboard

Once connected to Wi‑Fi, open the local IP address shown on the Wi‑Fi screen. The device serves a small dashboard with live IMU values and OSC settings.

The JSON endpoint is:

/imu.json

OSC output

OSC can be enabled from the IMU screen with a long press, or from the web dashboard. The default destination is 192.168.1.100:9000, and the default frequency is 50 Hz. The frequency can be configured between 1 and 200 Hz.

IMU data is sent to:

/rsbracelet/imu ax ay az gx gy gz

The OSC screen also allows sending a test message with a long press:

/rsbracelet/test "test"

Bracelet mode

The Bracelet screen displays a 32-square color preview on the M5StickC Plus2 screen.

Connecting the adressable LED bracelet to the port enables control over the bracelet's LEDs in ArtNet. More documentation will come with fully designed and tested bracelet.

Button controls

Short press: switch to the next screen.
Long press on Wi‑Fi: start Wi‑Fi configuration mode.
Long press on IMU: enable or disable OSC.
Long press on Bracelet: randomize the color preview.
Long press on OSC: send an OSC test message.
Long press on Lock: turn off the display.

Author, attribution, and contact

TinyMocap / RSbracelet firmware and documentation were created by Romaric SICHLER.

If you use this software, firmware, documentation, or ideas from this project in a public work, performance, installation, research project, publication, workshop, repository, or derivative project, please acknowledge the author and reference the TinyMocap / RSbracelet project.

Suggested acknowledgment (please contact me via email, Im always to happy to know about projects using my work !):

Project using TinyMocap firmware by Romaric SICHLER.

This project is experimental and under active development. Bugs, unexpected behavior, and hardware-specific issues may occur.

For bug reports, technical questions, collaboration, publication, or permission-related inquiries, please contact:

romaric.sichler@minesparis.psl.eu