This page boots real STM32F103 firmware — Blue Pill, GD32, Maple Mini,
Nucleo, F103RC, F105 — inside one WebAssembly module: a native Rust
ARM Cortex-M3 core plus the whole peripheral set. Pick a preset below
and press Run, or load your own
.bin / .hex / .elf.
Start with Blink or UART Echo, press Load preset, then Run. Output lands in the serial monitor below. Your own .bin/.hex/.elf works too — add a .map for readable PC symbols.