The Switch applies its stored SPI calibration when interpreting IMU data:
gyro_dps = (raw - spi_origin) * 936 / coeff
The firmware had real hardware offsets as calibration origins:
gyro_origin = (9, -22, -95) accel_origin = (-29, -199, 493)
A real Pro Controller sensor reads those values at rest, so the Switch
subtracts them to get zero. But our bridge already removes hardware bias
via gyro bias calibration and sends near-zero counts when still.
The Switch was then applying a second origin correction:
gyro_z=2 → (2 - (-95)) * 0.070 = 6.79 dps constant yaw rotation
This caused the character to spin horizontally even when holding the
controller perfectly still.
Fix: zero all calibration origins. The bridge handles bias correction;
the Switch must not apply a second offset on top.
- Add SwitchImuSample struct and IMU fields to SwitchInputState
- Add fill_imu_report_data() to pack samples into imuData[36]
- Rewrite switch_pro_apply_uart_packet() for v2 with checksum validation
- Enlarge poll_uart_frames() buffer to 64 bytes for variable-length frames
- Clear imu_sample_count after each USB report send (prevent stale IMU)
