Second screen

The EMF Camp 2026 talks schedule. Use the 5th screen to update it.

Third Screen

The badge radar, showing nearby badges in a Dragon Ball style.

Fourth screen

The badge's list, you can see all the badges around in a table view

Fifth screen

The Wi-Fi functionalities

TURN ON AP

Start the AP mode (move up the Dial Wheel Switch) and connect from your PC/phone to the badge AP using SSID and PASS shown; after that you can navigate to http://192.168.4.1 in order to explore more functionalities (hey Harry, can you play tetris?) and change configurations (saiyan is the pwd)

SYNC SCHEDULE

Start the SYNC mode (move down the Dial Wheel Switch) in order to update the schedule; the badge connects to the EMF Wi-Fi and downloads the latest talks schedule from emfcamp.org

Sixt Screen

Have fun while playing Snake! 🐍

Seventh Screen

Space Invaders! 👾 Roll a Dial Wheel UP to move the laser cannon left and DOWN to move it right, and press both wheels together to FIRE at the descending invaders. Your score and the all-time high score (saved on the badge) are shown at the top. Short-press a wheel to play again after game over.

Eighth Screen

Rainbow loop! 🌈 A continuous LED animation across all 7 front RGB LEDs — great for walking around camp and showing off some lights at night. It starts the moment you arrive on this screen and stops the moment you leave it. Short press either wheel to cycle through 5 animations: Rainbow Chase, Color Wave, Strobe Party, Twinkle Sparkle, and Comet Spin. The screen shows which one is currently playing.

Characteristics

The ESP32-C3 chip is the MCU at the core of the EMF Camp 2026 Badge, it integrates multiple peripherals to enable communication with the outside world. The number of available pins is limited to keep the chip package size small. To route all the incoming and outgoing signals a set of software programmable registers controls the pin multiplexer.

Peripheral Interfaces

There are 16 programmable GPIO pins available for:

• Digital interfaces
  • 3 SPI
  • 2 UART
  • I2C
  • I2S
  • Remote control peripheral, with 2 transmit channels and 2 receive channels
  • LED PWM controller, with up to 6 channels
  • Full-speed USB Serial/JTAG controller
  • General DMA controller (GDMA), with 3 transmit channels and 3 receive channels
  • TWAI® controller compatible with ISO 11898-1 (CAN Specification 2.0)
• Analog interfaces
  • 2 SAR ADCs (12-bit), up to 6 channels
  • Temperature sensor

Devices on board

The EMF Camp 2026 Badge is equipped with a 2.8 inch TFT color LCD screen with 240 x 320 pixels, using the ST7789 display controller. This display integrates a resistive touchscreen a white LEDs backlight and features an 18-pin standard FPC cable to interface the MCU with a 4-wire SPI bus.

The SPI bus signals are available on the connector labeled "SPI" at the top of the badge:

The current firmware version does not support touchscreen functionality, but the Badge still features the TSC2007 I2C Resistive Touch Screen Controller.

The front RGB LEDs are intelligent, individually addressable WS2812B chips that communicate with each other and the microcontroller via a single data line. The data transfer protocol uses a single NZR communication mode. The signal from the DOUT port of the last LED on the badge is available on the "1W" pin of the connector, labeled "I2C."

The I2C bus signals are available on the connector labeled "I2C" at the top of the badge:

The display backlight is controlled by 4 pins on the AW9523B LED driver and GPIO controller with I2C interface while the other 12 pins on the I/O ports can be configured as LED drive mode or GPIO mode and are available on the connector labeled "RGB*".

The I/O signals from AW9523B are available on the connector labeled "RGB*" at the left of the badge:

The badge's main input interface consists of two Dial Wheel Switches. These switches can be rotated up or down for short and long presses to navigate and interact with the UI. Pressing the center of the left switch results in the same effect as rotating the wheel UP, while pressing the center of the right switch results in the same effect as rotating the wheel DOWN.

Note: push the left switch (or rotating the wheel UP) during boot to put the MCU in Joint Download Boot mode to download binary files into flash using UART0 or USB interface. To reset/restart the MCU push the micro switch labeled "RST" on the top left of the badege.

Badge stuck on boot / factory reset

If a badge is stuck in a boot loop (serial log repeats esp_image: invalid segment length 0xffffffff / Factory app partition is not bootable), the firmware image itself is corrupt — most likely from a flash that got interrupted. Fix by reflashing over USB:

1. Press and hold the left dial's center button (this is the GPIO9 boot-mode strap).
2. While still holding it, connect the USB-C cable to the badge.
3. While still holding it, press and release the RST button.
4. Keep holding the left button for ~2 seconds after releasing RST, then release it.
5. Reflash both partitions:

   pio run -e emf2026-badge -t upload
   pio run -e emf2026-badge -t uploadfs
   

   (upload fixes the corrupted firmware; uploadfs refreshes the filesystem — settings/high scores regenerate from defaults on next boot.)

The badge's native USB-JTAG interface will normally re-enumerate on its own after the flash; if pio can't find the port automatically, pass it explicitly, e.g. --upload-port /dev/cu.usbmodemXXXX (find it with pio device list).

During the boot process, the messages by the ROM code can be printed to (Default) UART0 and USB Serial/JTAG controller.

The UART interface and the Strapping (button pin) signals are available on the connector labeled "RS232" at the top of the badge:

The USB-C connector's D+/D- pins are connected to the default USB Serial/JTAG Controller and the USB power is routed to the LiPo battery charger and the voltage regulators.

There is the MT3608 step-up converter intended for power the WS2812 with up to 5V and the MT3410LB step-down DC-DC 3.3V regulator, capable of delivering up to 1.3A output current to the MCU and all the other IC.

In case of low power and low noise applications it's possible to disable the MT3410LB by removing two 0 ohm resistors labeled SW_ON/SW_OUT and enable the RT9080 low-dropout (LDO) 3.3 voltage regulator by shorting two resistors pads labeled LDO_ON/LDO_OUT

The power lines are available on the connector labeled "POW" at the top of the badge:

The battery is charged using a TP4054 single-charge LiPo charger with a constant current/voltage algorithm and a DW01 protection IC designed to protect the battery from damage due to over-discharge and/or over-current. The charging circuit and voltage regulators are always powered by the USB port. A toggle switch for turning the badge on and off via the battery is located on the bottom of the badge.

Firmware architecture

For a detailed reference of the firmware — boot flow, FreeRTOS tasks, screens, BLE / Wi-Fi, the streaming schedule-sync pipeline, config & storage, the build/flash workflow and the non-obvious gotchas — see SKILL.md.

It is written as a Claude Code skill: copy it to .claude/skills/badge-architecture/SKILL.md in your clone and Claude Code will load it automatically when you work on the badge.

Toolchain setup

Prepare the environment

Visual Studio Code (VSCode)

Install Visual Studio Code as development environment:

• https://code.visualstudio.com/ - follow instructions there, if you don't have vscode yet.

PlatformIO (PIO) extension

Install PlatformIO extension on Visual Studio Code:

• Installation
• Quick Start
• User Guide

Please follow to the official documentation PlatformIO IDE for VSCode.

Setup the project

• Git clone this repository and open it on VSCode

If you get a No module named pkg_resources error, open the PlatformIO Core CLI and run:

• pip install setuptools

Build www data (Linux)

• Prerequisites:

  • Install Node.js and NPM

• Use NPM to Install required Packages:

  • npm install node-minify node-sass

• ./www-build.sh

Build www data (Docker)

• Install docker
• docker build --pull --rm -f "Dockerfile" -t emf2026badge:latest "."
• (Bash) docker run -it -v $(pwd)/public:/public -v $(pwd)/data/www:/output emf2026badge
• (Powershell) docker run -it -v ${PWD}/public:/public -v ${PWD}/data/www:/output emf2026badge

Build/Upload Filesystem

In order to upload the filesystem to the badge you need to plugin the badge using USB. In the "Project Tasks" view of PIO navigate to:

• emf2026-badge
  • Platform
    • Build Filesystem Image
    • Upload Filesystem Image

Build/Upload Firmware

In order to upload the firmware to the badge you need to plugin the badge using USB. In the "Project Tasks" view of PIO navigate to:

• emf2026-badge
  • General
    • Build
    • Upload

Known Issues

Check GitHub issue tracker

Misc

Wi-Fi SSID name lenght limit

The Wi-Fi SSID for connecting to an external Access Point (AP) is limited to 20 characters.

Use a different logo image

• Convert the BMP/JPG/PNG/SVG file to a C array. You can do this using an online image converter: use LVGL v8, CF_TRUE_COLOR_ALPHA as color format and and C array as output
• adjust main/badge/common/img_logo.c file