I built OS3-RNode as a tiny RNode-compatible LoRa modem firmware for CH32V003 + E22-900M22S.

It is based on a small deterministic event-driven core, with no scheduler, no threads, and bounded interrupt work. The goal was to make a minimal and auditable transport for Reticulum/NomadNet on very constrained hardware.

The article has the architecture notes and a firmware link. Feedback on the event model, failure handling, and interoperability tradeoffs would be useful.