Arduino for Phases 1–2 (Migration Path for Phase 3)

The first decision in building an OpenLCB node is: which platform and framework? For phases 1–2, we use Arduino because it’s the most accessible starting point for learning and offers excellent real-world functionality. Phase 3 introduces the migration path to full FreeRTOS-based solutions only if you need advanced features.

Why Arduino First?

Arduino provides a dramatically lower learning curve and barrier to entry compared to FreeRTOS or ESP-IDF:

Minimal setup time: You can have working code running in minutes without complex build systems or operating system knowledge
Large ecosystem: Thousands of tutorials, libraries, and community examples
Rapid iteration: Fast compile/upload cycle (with PlatformIO)
Breadboard-friendly: Ideal for learning with hobby microcontrollers
No RTOS complexity: Single-threaded execution; no threading, mutexes, or scheduler concepts needed

When learning OpenLCB, you want to focus on understanding the protocol and building real I/O functionality—not spending weeks learning RTOS concepts and debugging multi-threaded interactions. Arduino (with OpenMRN-Lite) lets you get working nodes immediately.

Arduino + OpenMRN-Lite: Phases 1–2

For phases 1–2 (TCP quick-start and CAN-based I/O), you use OpenMRN-Lite, the Arduino version of OpenMRN.

OpenMRN-Lite is production-quality and fully functional. It supports:

CDI configuration - Configure nodes without recompiling
CAN bus - Full CAN transport with proper arbitration
Event producers/consumers - The core OpenLCB pattern
Persistent storage - SPIFFS/SD card for configuration
Real-time monitoring - JMRI integration via TCP or CAN

This is not a compromise. Most hobby and DIY LCC installations use OpenMRN-Lite for years. You’re not learning a dead-end; you’re choosing the right tool for real-world I/O projects.

Do You Need Phase 3?

Most projects stay in phases 1–2. Phase 3 (FreeRTOS + Full OpenMRN) is only for advanced scenarios:

Command stations and bridges — Complex routing between multiple transports
Virtual nodes — Multiple logical nodes on one device
Traction protocol — Locomotive decoder features
Multi-threaded hubs — Complex systems requiring background threads and advanced concurrency

If you’re building sensors, I/O controllers, or simple nodes for a layout, phases 1–2 have everything you need. Most hobby and model railroad installations never require phase 3.

If You Need Phase 3 Later

If you eventually need phase 3 features, the foundation you built in phases 1–2 makes the path forward straightforward:

Your OpenLCB protocol knowledge transfers directly — message formats, event semantics, CDI structures all stay the same
You’ll switch from Arduino to ESP-IDF (Espressif’s full RTOS environment) and use full OpenMRN library instead of OpenMRN-Lite
You’ll add FreeRTOS-aware code (threading, message queues, etc.)
The core OpenLCB concepts you’ve mastered (producers/consumers, startup sequence, events) remain unchanged—you’re adding threading sophistication on top of a solid foundation

For Phases 1–2

We’ll use Arduino + OpenMRN-Lite. This combination gives you:

A working TCP node in minutes (phase 1)
A fully-featured CAN node for real layouts (phase 2)
Time to focus on OpenLCB concepts instead of RTOS complexity
A solid foundation for phase 3 if you ever need it

Let’s get started with simplicity, solid fundamentals, and the knowledge that you can expand whenever you need to.