drazzy.com (ATTinyCore index host) has had an expired TLS certificate
since 2026-06-22 and now 301-redirects http to https, defeating the
plain-http URL pinned to sidestep its TLS issues. Two failure modes:
1. A /root/.arduino15 volume from an older image can reference the index
in config while lacking the file; arduino-cli then fails instance
init outright, breaking EVERY compile, not just ATtiny (issue #254).
2. backend/Dockerfile chained update-index with &&, so any uncached
image build fails hard while the host is broken (exit 1 verified).
A stale index is harmless (ATTinyCore 1.4.1's platform archive and its
micronucleus 2.0a4 both download from github.com); a missing one is
fatal. So: vendor the index under backend/board-indexes/, copy it to
/opt/arduino15-seed in Dockerfile.standalone, and teach entrypoint.sh
to seed any missing package_*.json into /root/.arduino15 at boot,
healing stale volumes. backend/Dockerfile seeds the index directly and
makes update-index best-effort; core install lines stay strict.
Verified: removing the index reproduces the reporter's exact
'Error initializing instance' brick; after seeding, instance init
exits 0 with the host still broken.
ATTinyCore >=1.5.0 declares ATTinyCore:micronucleus@2.5-azd1b as a tool
dependency, hosted at https://azduino.com/bin/micronucleus/. That host
has been unreachable (connection refused) for extended periods, causing
every ATtiny85 compile to fail at the core-install step with:
Download failed: performing HEAD request: ... dial tcp ...: connection refused
Failed to install required core: ATTinyCore:avr
micronucleus is only used for USB upload — never for compilation — but
arduino-cli refuses to install a core whose tool deps cannot fetch.
Pin to 1.4.1, the last release whose micronucleus binary is hosted on
github.com (digistump release, reachable). The FQBN clock options we
ship (clock=16pll on attinyx5, etc.) are unchanged across 1.4.x.
- backend/app/services/arduino_cli.py: new CORE_INSTALL_VERSIONS map
consulted by ensure_core_for_board so the runtime auto-install
passes "ATTinyCore:avr@1.4.1" instead of unversioned latest.
- backend/Dockerfile and docker/entrypoint.sh: same pin so a fresh
image bakes 1.4.1 in and never hits the runtime fallback path.
Existing regression tests in test/backend/unit/test_arduino_cli_attinycore.py
still pass (they assert presence, not version).
- Implemented handshake tests to validate initial bus state and register responses.
- Created end-to-end tests for Pico W LED blinking using MicroPython firmware.
- Added SDPCM framing tests to ensure proper encoding and decoding of control frames.
- Developed IOCTL tests to verify command responses and state changes in the emulator.
- Established a full lifecycle test for WiFi operations, including scanning, connecting, and packet handling.
- Introduced TypeScript configuration for test files to ensure compatibility and strict type checking.
- Implemented `esp32_spi_chip_demo.ino` to demonstrate SPI communication with a 74HC595 shift register.
- Created `esp32_uart_chip_demo.ino` for UART loopback testing with ROT13 transformation.
- Added Python tests for compiling chips and sketches, ensuring valid WASM output and successful compilation for various board families.
- Developed end-to-end tests for ESP32 with custom chips using I2C and SPI, validating synchronous communication through the backend.
- Introduced GPIO bridge tests to verify serial communication and GPIO state changes.
- Ensured all tests validate the expected behavior of the custom chips and their interaction with the ESP32 firmware.
David Montero