# Design Document: MicroBadge

## Overview

**MicroBadge** is an interactive embedded application built for the BBC
micro:bit v2. It is written in **Rust** using the **Embassy** async embedded
runtime. The project functions as a **conference name badge** that acts as a
professional and technical icebreaker at events.

The application framework includes:
* A **menu system** for switching between apps.
* A **name scroller** for displaying your name or custom message.
* A **Snake game** for fun and interactivity.
* A **NFC business card** app for sharing contact info. **Still in progress**

## Goals

* Provide a custom and memorable name badge experience.
* Showcase embedded Rust development using async and no-std.
* Enable fun interactions and sharing via NFC.
* Serve as a technical portfolio piece for conferences, meetings, and
  interviews.

## Architecture

### 1. Core Framework

* Built on **Embassy** for asynchronous concurrency.
* Uses hardware abstraction layers (HALs) for GPIO, timers, display, and
  buttons.
* Implements a lightweight app-switcher system with a menu UI.

### 2. Applications

#### Name Scroller
* Scrolls a name or message across the LED matrix.
* Configurable for speed and repeat mode.
* Useful for identifying the wearer at a glance.

#### Snake Game
* Classic Snake game rendered on the 5x5 LED display.
* Uses `Button A` and `Button B` for turning.
* Includes food spawning, score tracking, and difficulty selection.
* Uses PWM for different intensity led lights.

#### NFC Business Card (WIP)
* Leverages the onboard NFC peripheral.
* Intends to share vCard/contact data over NFC.
* Targeted at mobile phones for quick transfer of contact info

## User Interaction

* Navigation is handled via micro:bit's `Button A`, `Button B`, and long-press `Start` gesture
* LED matrix provides visual feedback for game states and menu navigation
* Apps are selected from a simple menu UI
* Snake game is tuned to a slower speed (~4Hz) for usability

## Development Environment

* Written entirely in **Rust**, `#![no_std]`
* Uses **Embassy** for async device access and task scheduling
* Debugging output via `defmt`
* Built and flashed using `probe-rs` and `cargo-embed`

## Future Improvements

* Finalize NFC vCard transmission
* Add configuration storage via flash memory
* Create a desktop companion app for editing settings
* Support BLE for data sync or configuration

## Summary

MicroBadge combines a fun hardware platform with modern Rust development.
It serves not only as a name badge but also as a way to demonstrate embedded
skills, share contact info, and invite technical discussion at events.