Add coulomb counter for accurate SoC estimation independent of load:
- New coulomb_counter module: integrate current over time to track Ah consumed
* coulomb_counter_init(capacity_mah) initializes with battery capacity
* coulomb_counter_accumulate(current_ma) integrates current at 100 Hz
* coulomb_counter_get_soc_pct() returns SoC 0-100% (255 = invalid)
* coulomb_counter_reset() for charge-complete reset
- Battery module integration:
* battery_accumulate_coulombs() reads motor INA219 currents and accumulates
* battery_get_soc_coulomb() returns coulomb-based SoC with fallback to voltage
* Initialize coulomb counter at startup with DEFAULT_BATTERY_CAPACITY_MAH
- Telemetry updates:
* JLink STATUS: use coulomb SoC if available, fallback to voltage-based
* CRSF battery frame: now includes remaining capacity in mAh (from coulomb counter)
* CRSF capacity field was always 0; now reflects actual remaining mAh
- Mainloop integration:
* Call battery_accumulate_coulombs() every tick for continuous integration
* INA219 motor currents + 200 mA subsystem baseline = total battery draw
Motor current sources (INA219 addresses 0x40/0x41) provide most power draw;
Jetson ROS2 battery_node already prioritizes coulomb-based soc_pct from STATUS frame.
Default capacity: 2200 mAh (typical lab 3S LiPo); configurable via firmware parameter.
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Root cause 1 (IWDG reset loop): safety_init() was called before
mpu6000_init() — IWDG 50ms timeout fires during ~510ms IMU init,
causing infinite MCU reset. Moved safety_init() to after all
peripheral inits (IMU, hoverboard, balance).
Root cause 2 (DCache coherency): USB TX/RX buffers merged into a
single 512B-aligned struct in usbd_cdc_if.c. MPU Region 0 configured
non-cacheable (TEX=1, C=0, B=0) in usbd_conf.c USBD_LL_Init() before
HAL_PCD_Init(). DCache stays ON globally — MPU handles coherency.
Removed SCB_DisableDCache() from main.c (caused boot crash).
Also: fix safety.c IWDG_RELOAD macro (float literals not valid in
#if); add crsf.c stub so crsf_state links (UART not yet wired).
Fixes issue #9.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
