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Developer Guide

Welcome to the MyStation developer documentation. This guide provides technical details about the system architecture, implementation, and development processes.

For Developers​

This section is for developers who want to:

  • 🔧 Understand the system architecture
  • 📝 Contribute to the project
  • 🐛 Debug and fix issues
  • ✨ Add new features
  • 🔌 Modify hardware configuration

👤 Are you not a developer? See the User Guide instead.

Project Overview​

MyStation is an ESP32-based e-paper display system that shows real-time public transport departures and weather information.

Key Technologies​

  • Platform: ESP32-C3 / ESP32-S3
  • Framework: Arduino framework via PlatformIO
  • Display: 7.5" e-paper (GDEY075T7, 800x480)
  • Network: WiFi 2.4 GHz (802.11 b/g/n)
  • Storage: NVS (Non-Volatile Storage) for configuration
  • OTA: Over-the-air firmware updates
  • Power: Deep sleep with intelligent wake-up

Core Features​

  1. Configuration System - Multi-phase boot with web-based setup
  2. WiFi Management - Auto-connect, fallback, mDNS
  3. Display System - Multiple modes, efficient e-paper rendering
  4. Power Management - Deep sleep, battery monitoring, scheduled wake
  5. OTA Updates - Secure firmware updates over WiFi
  6. API Integration - Google Geolocation, RMV API, DWD Weather, OpenStreetMap Nominatim

Quick Navigation​

🏗️ Architecture & Design​

⚙️ Core Systems​

📡 Integration & APIs​

🛠️ Development​

🔌 Hardware​

Technology Stack​

Hardware​

ComponentModelPurpose
MCUESP32-C3 / S3Main processor
DisplayGDEY075T77.5" e-paper, 800x480
WiFiBuilt-in2.4 GHz 802.11 b/g/n
Storage4MB FlashFirmware + SPIFFS + NVS
Power3.7V LiPoBattery powered

Software​

LibraryVersionPurpose
PlatformIOLatestBuild system
Arduino-ESP326.5.0Framework
WiFiManager2.0.17WiFi configuration
ArduinoJson6.21.4JSON parsing
GxEPD21.6.4E-paper driver
U8g21.8.0Font rendering

APIs​

ServicePurposeAuthentication
Google GeolocationLocation detectionAPI Key
RMV APIPublic transport dataAPI Key
DWD WeatherWeather forecastsNone (open)
GitHubOTA updatesCertificate pinning

Key Concepts​

Configuration Phases​

MyStation uses a three-phase boot process:

  1. Phase 1: WiFi Setup - No WiFi configured, create AP
  2. Phase 2: App Setup - WiFi configured, need station config
  3. Phase 3: Operational - Fully configured, normal operation

See Boot Process for details.

Deep Sleep Cycle​

Normal operation follows this pattern:

Wake Up → Connect WiFi → Fetch Data → Update Display → Deep Sleep
  ↑                                                          │
  └──────────────────────────────────────────────────────────┘
                    (Configured interval)

Display Modes​

Three display modes supported:

  • DISPLAY_MODE_HALF_AND_HALF (0) - Weather + Departures
  • DISPLAY_MODE_WEATHER_ONLY (1) - Weather full screen
  • DISPLAY_MODE_DEPARTURE_ONLY (2) - Departures full screen

See Display System for rendering details.

Configuration Storage​

All settings stored in NVS (Non-Volatile Storage):

  • WiFi credentials (encrypted namespace)
  • Station configuration
  • Display preferences
  • Update intervals
  • Sleep schedule

See Configuration Layers for data structures.

Code Organization​

mystation/
├── src/                 # Source code
│   ├── main.cpp        # Entry point
│   ├── api/            # API clients
│   ├── config/         # Configuration
│   ├── display/        # Display rendering
│   ├── ota/            # OTA updates
│   ├── sec/            # Security (AES)
│   └── util/           # Utilities
├── include/            # Header files (mirrors src/)
├── lib/                # Libraries
├── test/               # Unit tests
├── data/               # SPIFFS files
├── docs/               # Documentation
└── platformio.ini      # Build configuration

Common Development Tasks​

Testing Changes​

# Run native tests
pio test -e native

# Run specific test
pio test -e native -f test_timing_manager

# Upload and monitor
pio run --target upload && pio device monitor

See Testing for test framework details.

Contributing​

Code Style​

  • Indentation: 4 spaces (no tabs)
  • Braces: K&R style (opening brace on same line)
  • Naming:
    • Classes: PascalCase
    • Functions: camelCase
    • Constants: UPPER_SNAKE_CASE
    • Variables: camelCase

refer .clang-format file for full style guide

Git Workflow​

  1. Fork the repository
  2. Create feature branch
  3. Make commits (atomic, well-described)
  4. Test thoroughly
  5. Submit pull request
  6. Address review comments

Documentation​

  • Update relevant documentation with code changes
  • Add examples for new features
  • Keep README.md current
  • Document breaking changes

Resources​

Documentation​

External Resources​

Community​

  • GitHub Issues - Bug reports and feature requests
  • Pull Requests - Code contributions
  • Discussions - Questions and ideas

Next Steps​

New to the Project?​

  1. Understand Boot Process
  2. Set up Development Environment

Ready to Code?​

  1. Check open issues for tasks
  2. Set up your development environment
  3. Start with small improvements
  4. Ask questions if stuck

Want to Contribute?​

  1. Read contributing guidelines
  2. Pick an issue or suggest a feature
  3. Discuss approach before major changes
  4. Write tests for new functionality
  5. Update documentation
  6. Submit pull request

Questions? Check the Troubleshooting Guide or open an issue on GitHub.