Device Setup

StemmaWeb bridges the physical and digital: it connects Adafruit StemmaQT sensors and modules to your browser, where they become live inputs for p5.js sketches. An Adafruit Trinkey RP2040 QT acts as the USB bridge — it speaks I²C to your sensors and WebUSB to your browser, no drivers required.

Hardware Requirements

Adafruit Trinkey RP2040 QT Required

A tiny USB stick with a built-in StemmaQT port. It plugs directly into your computer's USB-A port and acts as the firmware host.

adafruit.com/product/5056 →
StemmaQT Modules Optional

Attach one or more sensors via the StemmaQT (JST-SH 4-pin) connector. Modules can be daisy-chained. The following devices are currently supported:

  • — CO2 Sensor
  • — Distance Sensor
  • — Gyroscope
  • — Linear Encoder
  • — NeoDriver
  • — NFC Tag
  • — Pressure Sensor
  • — RFID Reader
  • — Rotary Encoder
  • — Touch Sensor
  • — Trinkey RP2040
  • — UV Sensor

Installing the Firmware

The Trinkey runs a custom firmware that handles the USB–I²C bridge. Installing it is a simple drag-and-drop — no software or toolchain needed.

  1. 1

    Put the Trinkey into bootloader mode

    While holding the BOOT button, press and release the RESET button (the small button on the side), then release BOOT. A drive called RPI-RP2 will appear on your computer.

    If the drive doesn't appear, try unplugging the Trinkey, then plugging it back in while holding BOOT.

  2. 2

    Download the firmware

    Download the prebuilt firmware file and copy it onto the RPI-RP2 drive.

    Download firmware.uf2
  3. 3

    Copy the file to the drive

    Drag firmware.uf2 onto the RPI-RP2 drive. The Trinkey will reboot automatically and the drive will disappear — the firmware is now running.

Build from Source

If you want to modify the firmware or build the latest version yourself, you need PlatformIO and a copy of the repository.

# Clone the repository
git clone git@github.com:sebastian-lenz/stemma-web.git
cd stemma-web/firmware

# Compile
pio run

# Compile and flash (Trinkey must already be in bootloader mode)
pio run --target upload

The compiled .uf2 file will be in .pio/build/adafruit_trinkey_qt2040/firmware.uf2 and can be copied manually as described above.