micro-rustscript

A portable RustScript VMBC runtime with release targets for ESP32-C3, ESP32-S31 preview hardware, and a native Arduino API simulator. Each ESP factory image contains its bootloader, partition table, platform runtime, pd-vm-nostd, framework host bridge, and a default VMBC program.

Flash complete images

ESP32-C3

Download micro-rustscript-esp32-c3.factory.bin from the latest GitHub Release and flash it at offset zero:

python -m esptool --chip esp32c3 erase_flash
python -m esptool --chip esp32c3 write_flash 0x0 micro-rustscript-esp32-c3.factory.bin

The ESP32-C3 boot order is fixed:

1. /rustscript/main.vmbc on an SD card connected with CS on GPIO 7. 2. The dedicated 64 KiB rustscript flash partition at 0x110000. 3. The serial VMBC REPL at 115200 baud.

An absent, unreadable, or missing SD script automatically falls through to the flash partition. The release factory image already contains esp32-blinky.vmbc in that partition. RUSTSCRIPT_SD_CS and RUSTSCRIPT_SD_PATH can be overridden with PlatformIO build flags.

ESP32-S31 preview

Download micro-rustscript-esp32-s31.factory.bin and flash the merged image at offset zero:

python -m esptool --chip esp32s31 write_flash 0x0 micro-rustscript-esp32-s31.factory.bin

The S31 preview image currently embeds the default VMBC program into the application at build time. Its runtime does not yet implement the C3 SD-card lookup, replaceable flash VMBC partition, or serial VMBC REPL. The release also includes the S31 ELF for debugging.

Targets and source layout

PlatformIO environment	Purpose	Platform integration	Main source
`esp32-c3-devkitm-1`	Flashable ESP32-C3 firmware	Official PlatformIO board plus Arduino-ESP32 and selected ESP-IDF APIs	shared `firmware/` sources
`esp32s31`	Flashable ESP32-S31 preview firmware	Pinned ESP-IDF master preview toolchain	`esp32s31/` CMake project
`arduino`	Native host simulation of a small Arduino API subset	PlatformIO `native` plus `firmware/simulator/`	`firmware/arduino/main.cpp`

Only ESP32-S31 has a top-level target directory because current PlatformIO releases do not provide an ESP32-S31 board definition or framework package. Its directory supplies the ESP-IDF project files that PlatformIO cannot generate: CMakeLists.txt, sdkconfig.defaults, partition layout, and the pure ESP-IDF application entry point. ESP32-C3 can use PlatformIO's standard esp32-c3-devkitm-1 board and therefore shares the normal firmware/ project. The arduino target is a native simulator rather than separate hardware; its target-specific source already lives under firmware/arduino/ and reuses the simulator compatibility layer.

All three are still first-class PlatformIO and release targets. The directory shape reflects their different build systems, not a difference in release status.