Like its sister-board, the ELM11-Feather (https://www.crowdsupply.com/brisbanesilicon/elm11-feather), the ELM11 is a highly-configurable microcontroller board programmable in Lua.

The goal is to introduce a new, natively scriptable, microcontroller board that is programmable in Lua. Unlike Python (the current offering of scriptable micros), Lua was specifically designed to be fast, efficient, and lightweight, making it a fantastic scripting language for embedded systems.

Key features include:

Executes Lua, from either:
REPL
There a standalone REPL for each CPU core.
Program(s) stored on the Flash
Compile-time configurable hardware
For example, CPU frequency, supported I/O protocols, hardware module injection, etc. See Build Hardware Overlay to build your own hardware overlay.
Run-time configurable hardware
For example, I/O protocol, I/O frequency, boot configuration, etc. See the ELM11 Datasheet.