FLOSS Weekly Episode 866 - BreezyBox and Embedded Compilers
Mar 18, 2026
Valentyn Danylchuk, an embedded-systems hobbyist behind BreezyBox and a compact self-hosting C compiler, discusses building an ESP32-based shell and toolkit. He covers the project’s origins, why a shell beats custom firmware, running relocatable ELF apps on-device, virtual terminals and graphics, SSH and portability choices, and plans for ports, compiler backends, and community contributions.
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PSRAM Enables Larger Embedded UIs
- Valentyn targets ESP32-S3 because its Wi‑Fi plus 8MB PSRAM make larger screens, buffers and more complex apps feasible.
- PSRAM is slower than internal RAM but enables screen buffers and bigger binaries on constrained devices.
Add SSH Early For Remote Debugging
- Prioritize SSH support if you want a useful embedded shell for debugging and remote diagnosis.
- Valentyn integrated existing SSH components and adapted them so built‑in commands display correctly, with some binaries needing small fixes before release.
Embedded Binaries Can Be Surprisingly Small
- The BreezyBox runtime is compact: about 150KB IRAM free and most PSRAM unused until needed.
- Example binaries are small (compiler ~16KB, Celeste port ~42KB) showing practical limits of on‑device ELF apps.