CMNode v0

The Open Hardware Badge by Codemotion

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An open-source electronic badge for developers who want to compile their own solutions.

cmnode.it · Report a Bug · Request Feature

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What is CMNode?

CMNode v0 is Codemotion's official open-source hardware badge — a programmable, reusable conference badge built for developers who want to push beyond just wearing a name tag. Powered by an ESP32-C3 (RISC-V architecture) and a 2.9" tri-color e-paper display, it shows your name, role, company, and a personalized QR code synced directly with the check-in system.

This is not disposable conference swag. It's a developer tool in badge form.

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Renders & Prototype

Front	Back	Prototype

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Hardware

Component	Details
MCU	ESP32-C3 Super Mini (RISC-V, WiFi, BLE)
Display	WeAct 2.9" E-Paper — Black / White / Red (GxEPD2_290_C90c)
Connectivity	USB-C (power + programming)
Prototyping	Full GPIO breakout with breadboard area

Full parts list: bom/Parts_BOM.csv

Pin Configuration (ESP32-C3)

EPD_CS   → GPIO 7
EPD_DC   → GPIO 1
EPD_RST  → GPIO 2
EPD_BUSY → GPIO 10
SCK      → GPIO 4  (hardware SPI default)
MOSI     → GPIO 6  (hardware SPI default)

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Firmware

The firmware is available in two flavors — choose the one that fits your workflow.

Option A — PlatformIO (Recommended)

Best for VS Code users. Handles library management, compilation, flashing, and serial monitoring automatically.

Requirements:

• VS Code + PlatformIO extension
• Or PlatformIO CLI

# Clone the repository
git clone https://github.com/Codemotion-Official/CMNode.git
cd CMNode

# Build and flash
pio run -t upload

# Open serial monitor
pio device monitor

The entry point is src/main.cpp. Libraries are defined in platformio.ini and installed automatically:

[env:esp32c3_supermini]
platform    = espressif32
board       = esp32-c3-devkitm-1
framework   = arduino
upload_speed = 115200

lib_deps =
    adafruit/Adafruit GFX Library
    adafruit/Adafruit BusIO
    https://github.com/ZinggJM/GxEPD2.git
    olikraus/U8g2_for_Adafruit_GFX@^1.8.0
    wallysalami/QRCodeGFX@^1.0.0

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Option B — Arduino IDE

Prefer a visual interface? Open NodeV0.ino directly in the Arduino IDE.

Requirements:

• Arduino IDE 2.x
• ESP32 board support (via Board Manager → add https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json)
• Install these libraries via Library Manager:

Library	Author
GxEPD2	ZinggJM
Adafruit GFX Library	Adafruit
Adafruit BusIO	Adafruit
U8g2_for_Adafruit_GFX	olikraus
QRCodeGFX	wallysalami

Select board: ESP32C3 Dev Module — then upload as usual.

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How It Works

Data Structure

struct BadgeData {
  String name;      // First name
  String surname;   // Last name
  String role;      // Job title
  String company;   // Company name
  String qrLink;    // URL encoded in the QR code
};

Serial Protocol

The badge listens on the serial port at 9600 baud. Send a single line in this format to update the display in real time:

Name;Surname;Role;Company;QRLink\n

Example:

Ada;Lovelace;Software Engineer;Codemotion;https://codemotion.com/profile/ada

The badge will parse the input, render the updated layout, and put the display into hibernate mode to save power.

Rendering Pipeline

parseSerialData()
       │
       ▼
   badge struct updated
       │
       ▼
  refreshDisplay()
       │
       ├── display.setFullWindow()
       ├── display.firstPage()
       │       └── drawContent()
       │               ├── Name & Surname (u8g2 font)
       │               ├── Role (smaller font)
       │               ├── Company (red, bold)
       │               └── QR Code (right-aligned)
       └── display.hibernate()

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Project Structure

CMNode/
├── src/
│   └── main.cpp          # PlatformIO entry point
├── NodeV0.ino            # Arduino IDE entry point (same logic)
├── platformio.ini        # PlatformIO configuration
├── include/              # Header files
├── lib/                  # Local libraries
├── test/                 # Test files
├── bom/
│   └── Parts_BOM.csv     # Bill of Materials
└── images/
    ├── render_front.png
    ├── render_back.png
    ├── prototype_photo.png
    ├── PCB.png
    └── SCH.png

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Contributing

CMNode is open to the entire Codemotion developer community. Whether you want to improve the firmware, design a new badge layout, build a companion app, or just share ideas — you are welcome here.

Ways to contribute:

• Open an Issue to report bugs or suggest features
• Submit a Pull Request with your improvements
• Share your custom badge layout or firmware extension
• Join the conversation on the Codemotion Discord

Please follow the standard GitHub flow: fork → branch → PR.

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License

Distributed under the MIT License. See LICENSE for details.

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Made with ♥ by the Codemotion team and community.