On boot, before the main loop, sample 1000 gyro readings (~1s) while
board is held still. Compute per-axis mean offset (sensor-frame raw LSBs)
and subtract from all subsequent readings in mpu6000_read().
- mpu6000_calibrate(): LED1+LED2 solid ON during 1s sample window,
resets filter state to zero once bias is known
- mpu6000_is_calibrated(): gate; main loop blocks arming and USB
streaming until calibration completes
- Bias subtracted in sensor frame before CW270 axis transform + scale,
so all three axes (pitch/roll/yaw rate) benefit
- config.h: GYRO_CAL_SAMPLES=1000
- No flash storage — recalibrate fresh each boot (bias varies with temp)
Closes#21 (3.5°/s yaw drift), #23 (gyro bias calibration on boot).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Adds motor_driver.c/h between the balance PID and the raw
hoverboard UART driver:
- Differential drive: balance_cmd → speed, steer_cmd → steer
- Steer-only ramping at MOTOR_STEER_RAMP_RATE (balance PID keeps
full immediate authority — no ramp on speed channel)
- Headroom clamp: reduces steer so |speed|+|steer|<=MOTOR_CMD_MAX
ensuring ESC never clips the balance command
- Emergency stop: latches on TILT_FAULT, clears on BALANCE_DISARMED;
send path stays in 50Hz ESC tick to avoid flooding UART
main.c: replace bare hoverboard_send() with motor_driver_update();
config.h: MOTOR_CMD_MAX=1000, MOTOR_STEER_RAMP_RATE=20 counts/ms
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Issue #12 — Roll displayed as pitch:
- Firmware was sending r=pitch_rate (wrong). Changed to r=roll_deg*10.
- mpu6000.c: add roll complementary filter (accel atan2(ay,az) +
gyro gy integration, same COMP_ALPHA=0.98 as pitch).
- IMUData: add roll and yaw fields.
- UI: updateIMU() now uses data.r/10 for roll (not client-side filter
that computed from ax/ay/az which firmware never sent).
- Three.js: roll -> rotation.z (banking), pitch -> rotation.x (tipping)
— axes were already correct, fix was the firmware data.
Issue #13 — Add yaw telemetry:
- Firmware: gyro Z integration (gz * dt) → s_yaw, sent as y=yaw_deg*10.
Gyro-only, drifts — no magnetometer.
- IMUData: yaw field added.
- UI: yaw -> rotation.y (spinning on vertical axis). Displayed in HUD.
- UI: YAW RESET button captures current yaw as new zero reference
(client-side offset, no new firmware command needed).
Closes#12, #13.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Safety systems implementation:
IWDG Hardware Watchdog (50ms timeout, config.h WATCHDOG_TIMEOUT_MS):
- safety_init() configures IWDG at PSC/32 (0.8ms tick), reload=62
- safety_refresh() must be called every loop iteration
- Cannot be disabled once started — MCU resets if loop hangs
- Started after 3s USB init delay (avoids spurious startup reset)
Arm Hold Interlock (3s, config.h ARMING_HOLD_MS):
- Arm command starts a hold timer, not immediate motor enable
- Motors only enable after ARMING_HOLD_MS consecutive hold
- Disarm or tilt > 10° cancels pending arm
- Prevents accidental arm from single keypress
Tilt Fault Alert:
- safety_alert_tilt_fault() fires one-shot buzzer on TILT_FAULT edge
- Rider hears alarm when tilt cutoff triggers
- Edge-detected (buzzer only fires once per fault event)
RC Timeout (infrastructure):
- safety_rc_alive() checks crsf_state.last_rx_ms vs RC_TIMEOUT_MS
- RC disarm wired but guarded (no CRSF yet) — remove guard when wired
- Compatible with future CRSF implementation
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
