End-to-end implementation of Sprint 1 per docs/sprint-1-plan.md.
Builds: pio run -e esp32-dev SUCCESS, RAM 6.7%, Flash 26.5% (347 KB).
Tests: pytest 110/110 green; pio test -e native deferred (needs host
C++ compiler -- none on this Windows machine).
Firmware (firmware/ar_autopilot_v1/):
- platformio.ini: 4 envs (esp32-dev release, esp32-debug, native unity
tests, check static analysis). NMEA2000-library@4.22, NMEA2000_esp32@
1.0, eModbus@1.7.4 pinned.
- main.cpp: boot in STANDBY, FreeRTOS task spawn, returns to scheduler.
- system/: ar_log.h facade, task_config.h (priorities/stacks/cores
central table), heartbeat (1 Hz LED + uptime).
- modes/: STANDBY-only state machine; non-STANDBY rejected.
- hal/: di_do.cpp (5 DI + 10 DO with debounce + last-state cache),
rudder_sensor.cpp (100 Hz ADC + 5-sample median filter, Core 1),
rudder_actuator.cpp (DO1/DO2/DO3 with three safety interlocks:
power-off, STANDBY mode, limit switch).
- safety/: TWDT @ 2 s panic-on-expire; 50 Hz safety task on Core 1
enforcing DI1 physical disengage button, DI4 external alarm,
both-limit-switch interlock.
- protocols/modbus_slave.cpp: eModbus RTU server on UART2 @ 38400 8N1,
slave ID 1. 17 inputs + 19 discretes + 5 holdings + 4 coils. Reads
pull live telemetry; writes validate range and route to handlers.
- protocols/nmea2000_consumer.cpp: stack open with CAN TX=GPIO3
RX=GPIO1, subscribed to PGN 127250 (Heading) + PGN 127251 (Rate of
Turn). 5 s staleness flag built in for Sprint 6 alarm wiring.
- filters/median.h: templated MedianFilter<T,N> (host testable).
Cross-cutting:
- modbus_registers.yaml: single source of truth for the Modbus register
map. 45 entries.
- tools/gen_modbus_registers.py: YAML -> C++ header + Python module
generator with --check for drift detection.
- arautopilot/shared/modbus_register_map.py: generated Python mirror,
imported by Studio + tools.
- arautopilot/tests/test_modbus_register_map.py: 30 tests covering
schema, address uniqueness, range, spot-checks, and drift detection
(fails if YAML edited without regenerating).
- firmware/ar_autopilot_v1/tools/modbus_client_test.py: manual Modbus
client for poking the slave from a PC with USB-RS485 dongle.
- firmware/ar_autopilot_v1/test/test_median_filter/test_median.cpp:
8 Unity tests of the median filter (host-side, no Arduino dependency).
- docs/firmware.md: full operator + integrator guide (toolchain, build,
flash, expected boot log, troubleshooting, Sprint 1 capability matrix).
Architecture note: opted for Arduino-on-ESP32 only instead of the
proposed dual Arduino-as-ESP-IDF-component setup. Rationale documented
in CHANGELOG and docs/firmware.md -- Arduino-on-ESP32 already provides
the FreeRTOS primitives we need; dual framework adds fragility without
benefit at Sprint 1 scope. Reconsider in Sprint 8 (OTA + secure boot).
NOT in Sprint 1 (intentional per brief sec. 12):
- PID loops (inner/outer)
- True Course / Track Keeping
- Full alarm catalogue beyond DI1/DI4
- Knob driver
- Studio GUI / dedicated display
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
