Erlang on a Microcontroller: Davide Bettio & Paul Guyot on AtomVM

In 1952, Marvin Minsky and Claude Shannon built a box with a single switch. When you flip it, the only thing it does is reach out and switch itself back off. Seventy years later, 5,000 of those boxes are sitting on desks worldwide — and the thing making them tick is Erlang, running on a chip smaller than a fingernail.

Davide Bettio built AtomVM, the virtual machine that makes this possible. Paul Guyot wrote the Erlang firmware, added SMP support as a weekend project, and shipped 5,000 units.

Topics include:

• what AtomVM is — a from-scratch BEAM-compatible VM for microcontrollers with a few hundred kilobytes of RAM and no OS

• debugging a virtual machine with no stack traces: printf everywhere, blindfolded

• the first production batch with a 5–10% return rate that turned out to be a mechanical problem — after Paul rewrote half the software looking for a bug that wasn't there

• why the actor model, let it crash, and binary pattern matching are unusually well-suited to embedded devices

• what AtomVM actually supports: GenServer, maps, JSON, Erlang distribution, and via the Popcorn project — Phoenix LiveView on a microcontroller

• Paul's SMP implementation as a "mixed blessing" — added for purely selfish engineering reasons, then forced the whole team to rewrite their drivers

• where AtomVM differs from the BEAM: no dirty schedulers, no hot code unloading, a simpler scheduler model that mostly doesn't surface at the API level

Recorded June 24, 2026.

Resources mentioned:

• atomvm.net

• GitHub: atomvm/AtomVM

• Popcorn project — Phoenix LiveView on AtomVM

• Discord: AtomVM community