Add a working microSD card part backed by a FAT16 image, following the
Wokwi storage model: the project's own workspace files are auto-copied
onto the card (free), and an optional "SD Card" panel uploads extra
files (gated as a paid feature by the velxio.dev overlay; OSS default
allows it).
Frontend (in-browser AVR / RP2040):
- ProtocolParts.ts: rewrite the microsd-card part from a handshake stub
into a real SD-over-SPI device (reply-first Ncr timing, SDSC byte
addressing, single/multi-block read+write, CSD/CID, full CMD set).
- utils/fatImage.ts: dependency-free FAT16 super-floppy builder (8.3 + LFN).
- utils/sdCardFiles.ts: assemble the card image from workspace files plus
uploaded files; base64 helpers.
- components/simulator/SdCardPanel.tsx + ComponentPropertyDialog: upload UI.
- DynamicComponent + useSimulatorStore: build and inject the image on run.
- lib/proSdCardGate.ts: overlay-installable gate for the upload action.
- data/examples-storage-microsd.ts: Arduino Uno + ESP32 gallery examples.
Backend (ESP32 via QEMU):
- services/esp32_sd_slave.py: synchronous SD-over-SPI slave (Python port of
the browser part) with a sparse backing store, idle-state R1 tracking and
real CRC16 on data blocks when the host enables CRC (CMD59) -- both
required by ESP-IDF's sdspi driver.
- esp32_worker.py: route SPI bytes to the slave (returns MISO synchronously)
and feed write-only bulk transfers.
- esp32_lib_manager.py + routes/simulation.py: forward the FAT image
(sd_card.image_b64) from the start config into the worker.
Tested:
- frontend: protocol-parts, fat-image, sd-card-gate and microsd-real-firmware
(real Arduino SD.h on avr8js) -- 86 passing.
- backend: test_esp32_sd_slave (10) covering the ESP-IDF init sequence and
CRC16; validated end to end by running a real SD.h sketch in libqemu-xtensa
(mount, directory listing, read and write-readback).
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