Here are the classes, structs, unions and interfaces with brief descriptions:

[detail level 1234]

▼Nm5	Top level namespace of M5Stack
▼Nimu
▼CAhrsController	Merges up to 4 IMUDataSource instances by capability and fuses their samples into an attitude estimate via a pluggable AhrsFilterBase
Ccalibration_data_t	Exportable/importable snapshot of every capability's auto-calibration offset
CAhrsFilterBase	Framework-independent contract shared by every AHRS attitude filter
▼CAhrsImu	AhrsController plus an M5Unified IMU_Class-compatible API
Cimu_3d_t	3-axis float vector, layout-compatible with m5::IMU_Class::imu_3d_t
Cimu_data_t	Merged accel/gyro/mag sample, layout-compatible with m5::IMU_Class::imu_data_t
CAxisOrder	Chip-frame-to-body-frame axis remap: a permutation plus a per-output-axis sign flip
CComplementaryFilter	Angle-based first-order complementary filter
CEKFFilter	Quaternion extended Kalman filter (EKF) with gyro bias estimation
CFusionFilter	Adapter around the vendored x-io Fusion AHRS algorithm (x-io Technologies, MIT license; see src/imu/filter/third_party/fusion)
Cimu_convert_param_t	Raw to physical unit conversion coefficients
Cimu_physical_data_t	Merged, converted physical-unit IMU sample (AhrsController::latest())
Cimu_raw_data_t	Unified raw data (chip-native axes, no remap applied)
CIMUDataSource	Thin contract between measurement units and consumers (e.g. AHRS)
CMadgwickFilter	Gradient-descent orientation filter (Madgwick 2010)
CMahonyFilter	Explicit complementary filter with proportional-integral feedback (Mahony et al. 2008)
CVQFFilter	Adapter around the vendored VQF algorithm (Daniel Laidig, MIT license; see src/imu/filter/third_party/vqf)
▼Nmath
CMatrix	Fixed-size (R rows x C columns) float matrix, std::array backed (no heap allocation)
CQuaternion	Plain Hamilton quaternion (float) used to represent attitude
CVector3	Plain 3D vector (float)
▼Nunit
▼Nak8963
CData	One AK8963 sample: an 8-byte burst from ST1 (0x02) plus the device ASA trim
▼Nbmi270
CData	One measurement. Accel/gyro are always 12 bytes, little-endian (register 0x0C when the AUX/BMM150 bridge is not in use, or bytes [8..19] of the 20 byte burst from register 0x04 when it is; see UnitBMI270::read_measurement())
▼Nbmm150
CData	One measurement (8 bytes burst from REG_DATA_X_LSB, register 0x42)
Ctrim_t	Factory trim (calibration) values read from registers 0x5D-0x71, consumed by the compensation formulas in Data::comp_x()/comp_y()/comp_z()
▼Nbmm350
CData	One measurement (12 bytes burst from REG_MAG_X_XLSB, register 0x31): 9 bytes magnetometer (X,Y,Z, 24bit little-endian each) followed by 3 bytes temperature (24bit little-endian)
Cotp_compensation_t	Per-chip OTP compensation coefficients (read out at boot from the sensor's one-time-programmable memory), consumed by compensate_temp() and compensate_mag(). All-zero (default-constructed, aside from t0) is a neutral / pass-through configuration
▼Nmag3110
CData	One MAG3110 sample: a 7-byte burst from DR_STATUS (0x00)
▼Nmpu6886
CData	One measurement (14 bytes burst from REG_ACCEL_XOUT_H, big-endian)
▼Nsh200q
CData	One measurement (14 bytes burst from REG_OUTPUT, little-endian – NOT the MPU byte order)
▼CUnitAK8963	3-axis magnetometer unit. No standalone GROVE unit exists; it is the magnetometer embedded in the MPU9250 found on early classic M5Stack Core/Fire boards, reachable at 0x0C once the MPU9250's I2C bypass is enabled (see m5::unit::imu::enableAuxBypass)
Cconfig_t	Settings for begin()
▼CUnitBMI270	6-axis (accel + gyro) IMU unit. CoreS3/AtomS3R built-in
Cconfig_t	Settings for begin()
▼CUnitBMI270AuxBMM150	BMI270 that switches on its auxiliary (AUX) interface and drives a BMM150 through it
Cconfig_t	Settings for begin(), extending the base with the magnetometer's own
▼CUnitBMM150	3-axis magnetometer unit. No standalone GROVE unit exists for this chip; it is found built into some boards (e.g. classic M5Stack Core/Fire, paired with MPU6886) and as the auxiliary sensor of UnitBMI270
Cconfig_t	Settings for begin()
▼CUnitBMM350	3-axis magnetometer unit (U231, GROVE)
Cconfig_t	Settings for begin()
CUnitDoF10	Unit DoF10: BMI270 + BMM350 + SPA06, all directly on the GROVE main bus (no AUX bypass). The BMI270 address is SW1-selectable (0x68 default / 0x69); pass it to the constructor (e.g. from bmi270::detectAddress). BMM350 is fixed at 0x14, SPA06 is fixed at 0x76. Add imu() and mag() to an AhrsController; read baro() directly (not AHRS-fused)
CUnitDoF9	Unit DoF9: BMI270 + BMM350, both directly on the GROVE main bus (no AUX bypass). The BMI270 address is SW1-selectable (0x68 default / 0x69); pass it to the constructor (e.g. from bmi270::detectAddress). BMM350 is fixed at 0x14. Add imu() and mag() to an AhrsController
▼CUnitMAG3110	NXP/Freescale MAG3110 3-axis magnetometer. No standalone GROVE unit exists; it is the magnetometer on the original (2017) classic M5Stack Gray (paired with an MPU6050). It sits directly on the host I2C bus at 0x0E (no aux bypass needed, unlike the MPU9250's AK8963)
Cconfig_t	Settings for begin()
CUnitMiniIMUPro	Unit Mini IMU-Pro (U171): BMI270 (0x68, fixed – no address switch) + BMP280 (0x76) on the GROVE main bus, with a BMM150 magnetometer wired to the BMI270's AUX interface (ASDX/ASCX), not to the main bus. The predecessor of Unit DoF9/DoF10, with a BMM150/BMP280 instead of the BMM350/SPA06
CUnitMPU6050	TDK InvenSense MPU-6050 6-axis IMU (accel + gyro + temp). WHO_AM_I 0x68
CUnitMPU6500	TDK InvenSense MPU-6500 6-axis core (accel + gyro + temp)
CUnitMPU6886	TDK InvenSense MPU-6886 6-axis IMU (accel + gyro + temp). WHO_AM_I 0x19
▼CUnitMPU6xxx	Shared base for the TDK InvenSense MPU 6-axis family (accel + gyro + temp)
Cconfig_t	Settings for begin()
CUnitMPU9250	TDK InvenSense MPU-9250 9-axis IMU. Accel/gyro/temp (this unit itself) + AK8963 mag (mag())
▼CUnitSH200Q	Senodia SH200Q 6-axis IMU (accel + gyro + temp). No standalone GROVE unit exists; it is the built-in IMU of the earliest (2019.3) M5StickC and of the 2019.7 M5Stack Fire (there paired with a discrete BMM150 magnetometer), on the internal I2C bus at 0x6C
Cconfig_t	Settings for begin()