The esp32/s3/c3 MicroPython bins were v1.20.0 (April 2023) — built by
micropython.org on IDF 4.4, three IDF generations behind the compile
pipeline and the engines' own validation corpus (both IDF 5.5), and two
behind the C6 bin (already v1.28). That drift is what broke I2C on the
S3: the engines decode the IDF 5.x driver sequences, and the v1.20 image
drove them the 4.4 way.
All four families now ship v1.28.0 (2026-04-06, IDF 5.x). Remote URLs
and cache keys move together, so a browser holding the old bin in
IndexedDB misses the new key and fetches v1.28 on its own. The new
images all declare 4 MB flash — padToFlashSize's floor exactly (the old
S3 bin declared 8 MB).
Validated cold on each engine (boot -> REPL, i2c.scan finds an attached
slave, WLAN scan/connect/DHCP; S3 additionally quad-PSRAM with a
multi-MB heap) and in the app (scan [60] on esp32/s3/c3, the ssd1306
gallery example drawing). Companion engine release: esp32s3js v1.16.0
(I2C interrupts on both cores, quad-PSRAM data plane). Pin.toggle() and
three years of upstream fixes come along; the v1.20 Pin.toggle note in
the editor seed is now history only.
Residual risk, flagged not fixed: the OSS QEMU self-host path (no JS
engines) now boots v1.28 under QEMU — unvalidated here, velxio.dev does
not exercise it.
These binaries are loaded at runtime from /firmware/ (cyw43 installer,
RP2350 simulator, C6 bridge) and were living only in the prod working
tree — a fresh checkout would 404 them. Sitemap regenerated 2026-08-13.
ESP32-C3 already uses the QEMU backend via Esp32Bridge, not browser-side
emulation. This adds MicroPython support by including C3 in the supported
set, adding the C3 firmware variant to the loader, and bundling the
fallback firmware binary.
Also fixes misleading type comments that said "browser emulation" for C3
boards — they actually use QEMU backend.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Extends MicroPython support (Phase 2) to ESP32 Xtensa boards running on
QEMU. Firmware is downloaded from micropython.org, cached in IndexedDB,
and loaded into QEMU. User code is injected via the raw-paste REPL
protocol after the MicroPython REPL boots.
- Create Esp32MicroPythonLoader.ts for firmware download/cache
- Add raw-paste REPL injection (Ctrl+A → Ctrl+E → code → Ctrl+D) to Esp32Bridge
- Extend loadMicroPythonProgram in store for ESP32 path
- Add ESP32 default MicroPython content (GPIO 2 blink)
- Simplify SerialMonitor Ctrl+C/D to work for all MicroPython boards
- Bundle fallback firmware for ESP32 and ESP32-S3
- Add all ESP32 board variants to SerialMonitor tab maps
Closes#3 (Phase 2)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Implements MicroPython emulation for Raspberry Pi Pico boards running
entirely in the browser using rp2040js. Users can toggle between
Arduino C++ and MicroPython modes via a language selector dropdown.
Key changes:
- Add LanguageMode type and BOARD_SUPPORTS_MICROPYTHON to board types
- Create MicroPythonLoader.ts: UF2 firmware parser, LittleFS filesystem
builder (via littlefs-wasm), IndexedDB firmware caching
- Extend RP2040Simulator with loadMicroPython() method using USBCDC for
serial REPL instead of UART
- Add setBoardLanguageMode and loadMicroPythonProgram store actions
- Update EditorToolbar with language toggle and MicroPython compile flow
- Enhance SerialMonitor with REPL label, Ctrl+C/D support
- Bundle MicroPython v1.20.0 UF2 firmware as fallback in public/firmware/
- Update useEditorStore to create main.py default for MicroPython mode
Closes#3
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
David Montero Crespo