ardupilot/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.cpp

/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
/*
  driver for Invensensev3 IMUs

  Supported:
   ICM-40609
   ICM-42688
   ICM-42605
   ICM-40605 - EOL
   IIM-42652
   ICM-42670

  Note that this sensor includes 32kHz internal sampling and an
  anti-aliasing filter, which means this driver can be a lot simpler
  than the Invensense and Invensensev2 drivers which need to handle
  8kHz sample rates to achieve decent aliasing protection
 */

#include <AP_HAL/AP_HAL.h>
#include "AP_InertialSensor_Invensensev3.h"
#include <utility>
#include <stdio.h>

extern const AP_HAL::HAL& hal;

/*
  gyro as 16.4 LSB/DPS at scale factor of +/- 2000dps (FS_SEL==0)
 */
static const float GYRO_SCALE = (0.0174532f / 16.4f);

// set bit 0x80 in register ID for read on SPI
#define BIT_READ_FLAG                           0x80

// registers we use
#define INV3REG_WHOAMI        0x75
#define INV3REG_FIFO_CONFIG   0x16
#define INV3REG_PWR_MGMT0     0x4e
#define INV3REG_GYRO_CONFIG0  0x4f
#define INV3REG_ACCEL_CONFIG0 0x50
#define INV3REG_GYRO_CONFIG1  0x51
#define INV3REG_GYRO_ACCEL_CONFIG0 0x52
#define INV3REG_ACCEL_CONFIG1 0x53
#define INV3REG_FIFO_CONFIG1  0x5f
#define INV3REG_FIFO_CONFIG2  0x60
#define INV3REG_FIFO_CONFIG3  0x61
#define INV3REG_SIGNAL_PATH_RESET 0x4b
#define INV3REG_INTF_CONFIG0  0x4c
#define INV3REG_FIFO_COUNTH   0x2e
#define INV3REG_FIFO_DATA     0x30
#define INV3REG_BANK_SEL      0x76

// ICM42688 bank1
#define INV3REG_GYRO_CONFIG_STATIC2 0x0B
#define INV3REG_GYRO_CONFIG_STATIC3 0x0C
#define INV3REG_GYRO_CONFIG_STATIC4 0x0D
#define INV3REG_GYRO_CONFIG_STATIC5 0x0E

// ICM42688 bank2
#define INV3REG_ACCEL_CONFIG_STATIC2 0x03
#define INV3REG_ACCEL_CONFIG_STATIC3 0x04
#define INV3REG_ACCEL_CONFIG_STATIC4 0x05

// registers for ICM-42670, multi-bank
#define INV3REG_70_PWR_MGMT0  0x1F
#define INV3REG_70_GYRO_CONFIG0  0x20
#define INV3REG_70_GYRO_CONFIG1  0x23
#define INV3REG_70_ACCEL_CONFIG0 0x21
#define INV3REG_70_ACCEL_CONFIG1 0x24
#define INV3REG_70_FIFO_COUNTH   0x3D
#define INV3REG_70_FIFO_DATA     0x3F
#define INV3REG_70_INTF_CONFIG0  0x35
#define INV3REG_70_MCLK_RDY      0x00
#define INV3REG_70_SIGNAL_PATH_RESET 0x02
#define INV3REG_70_FIFO_CONFIG1  0x28
#define INV3REG_BLK_SEL_W 0x79
#define INV3REG_BLK_SEL_R 0x7C
#define INV3REG_MADDR_W   0x7A
#define INV3REG_MADDR_R   0x7D
#define INV3REG_M_W       0x7B
#define INV3REG_M_R       0x7E
#define INV3REG_BANK_MREG1 0x00
#define INV3REG_BANK_MREG2 0x28
#define INV3REG_BANK_MREG3 0x50

#define INV3REG_MREG1_FIFO_CONFIG5 0x1
#define INV3REG_MREG1_SENSOR_CONFIG3 0x06

// WHOAMI values
#define INV3_ID_ICM40605      0x33
#define INV3_ID_ICM40609      0x3b
#define INV3_ID_ICM42605      0x42
#define INV3_ID_ICM42688      0x47
#define INV3_ID_IIM42652      0x6f
#define INV3_ID_ICM42670      0x67

/*
  really nice that this sensor has an option to request little-endian
  data
 */
struct PACKED FIFOData {
    uint8_t header;
    int16_t accel[3];
    int16_t gyro[3];
    int8_t temperature;
    uint16_t timestamp;
};

#define INV3_SAMPLE_SIZE sizeof(FIFOData)
#define INV3_FIFO_BUFFER_LEN 8

AP_InertialSensor_Invensensev3::AP_InertialSensor_Invensensev3(AP_InertialSensor &imu,
                                                               AP_HAL::OwnPtr<AP_HAL::Device> _dev,
                                                               enum Rotation _rotation)
    : AP_InertialSensor_Backend(imu)
    , rotation(_rotation)
    , dev(std::move(_dev))
{
}

AP_InertialSensor_Invensensev3::~AP_InertialSensor_Invensensev3()
{
    if (fifo_buffer != nullptr) {
        hal.util->free_type((void*)fifo_buffer, INV3_FIFO_BUFFER_LEN * INV3_SAMPLE_SIZE, AP_HAL::Util::MEM_DMA_SAFE);
    }
}

AP_InertialSensor_Backend *AP_InertialSensor_Invensensev3::probe(AP_InertialSensor &imu,
                                                                 AP_HAL::OwnPtr<AP_HAL::Device> _dev,
                                                                 enum Rotation _rotation)
{
    if (!_dev) {
        return nullptr;
    }

    if (_dev->bus_type() == AP_HAL::Device::BUS_TYPE_SPI) {
        _dev->set_read_flag(BIT_READ_FLAG);
    }

    AP_InertialSensor_Invensensev3 *sensor =
        new AP_InertialSensor_Invensensev3(imu, std::move(_dev), _rotation);
    if (!sensor || !sensor->hardware_init()) {
        delete sensor;
        return nullptr;
    }

    return sensor;
}

void AP_InertialSensor_Invensensev3::fifo_reset()
{
    if (inv3_type == Invensensev3_Type::ICM42670) {
        // FIFO_FLUSH
        register_write(INV3REG_70_SIGNAL_PATH_RESET, 0x04);
    } else {
        // FIFO_MODE stop-on-full
        register_write(INV3REG_FIFO_CONFIG, 0x80);
        // FIFO partial disable, enable accel, gyro, temperature
        register_write(INV3REG_FIFO_CONFIG1, fifo_config1);
        // little-endian, fifo count in records, last data hold for ODR mismatch
        register_write(INV3REG_INTF_CONFIG0, 0xC0);
        register_write(INV3REG_SIGNAL_PATH_RESET, 2);
    }

    notify_accel_fifo_reset(accel_instance);
    notify_gyro_fifo_reset(gyro_instance);
}

void AP_InertialSensor_Invensensev3::start()
{
    WITH_SEMAPHORE(dev->get_semaphore());

    // initially run the bus at low speed
    dev->set_speed(AP_HAL::Device::SPEED_LOW);

    // grab the used instances
    enum DevTypes devtype;
    switch (inv3_type) {
    case Invensensev3_Type::IIM42652:
        devtype = DEVTYPE_INS_IIM42652;
        fifo_config1 = 0x07;
        temp_sensitivity = 1.0 / 2.07;
        break;
    case Invensensev3_Type::ICM42688:
        devtype = DEVTYPE_INS_ICM42688;
        fifo_config1 = 0x07;
        temp_sensitivity = 1.0 / 2.07;
        break;
    case Invensensev3_Type::ICM42605:
        devtype = DEVTYPE_INS_ICM42605;
        fifo_config1 = 0x07;
        temp_sensitivity = 1.0 / 2.07;
        break;
    case Invensensev3_Type::ICM40605:
        devtype = DEVTYPE_INS_ICM40605;
        fifo_config1 = 0x0F;
        temp_sensitivity = 1.0 * 128 / 115.49;
        break;
    case Invensensev3_Type::ICM42670:
        devtype = DEVTYPE_INS_ICM42670;
        temp_sensitivity = 1.0 / 2.0;
        break;
    case Invensensev3_Type::ICM40609:
    default:
        devtype = DEVTYPE_INS_ICM40609;
        temp_sensitivity = 1.0 / 2.07;
        fifo_config1 = 0x07;
        break;
    }

    // always use FIFO
    fifo_reset();

    // setup on-sensor filtering and scaling and backend rate
    if (inv3_type == Invensensev3_Type::ICM42670) {
        set_filter_and_scaling_icm42670();
    } else {
        set_filter_and_scaling();
    }

    // pre-calculate backend period
    backend_period_us = 1000000UL / backend_rate_hz;

    if (!_imu.register_gyro(gyro_instance, backend_rate_hz, dev->get_bus_id_devtype(devtype)) ||
        !_imu.register_accel(accel_instance, backend_rate_hz, dev->get_bus_id_devtype(devtype))) {
        return;
    }

    // update backend sample rate
    _set_accel_raw_sample_rate(accel_instance, backend_rate_hz);
    _set_gyro_raw_sample_rate(gyro_instance, backend_rate_hz);

    // indicate what multiplier is appropriate for the sensors'
    // readings to fit them into an int16_t:
    _set_raw_sample_accel_multiplier(accel_instance, multiplier_accel);

    // now that we have initialised, we set the bus speed to high
    dev->set_speed(AP_HAL::Device::SPEED_HIGH);

    // setup sensor rotations from probe()
    set_gyro_orientation(gyro_instance, rotation);
    set_accel_orientation(accel_instance, rotation);

    // allocate fifo buffer
    fifo_buffer = (FIFOData *)hal.util->malloc_type(INV3_FIFO_BUFFER_LEN * INV3_SAMPLE_SIZE, AP_HAL::Util::MEM_DMA_SAFE);
    if (fifo_buffer == nullptr) {
        AP_HAL::panic("Invensensev3: Unable to allocate FIFO buffer");
    }

    // start the timer process to read samples, using the fastest rate avilable
    periodic_handle = dev->register_periodic_callback(backend_period_us, FUNCTOR_BIND_MEMBER(&AP_InertialSensor_Invensensev3::read_fifo, void));
}

// get a startup banner to output to the GCS
bool AP_InertialSensor_Invensensev3::get_output_banner(char* banner, uint8_t banner_len) {
    if (fast_sampling) {
        snprintf(banner, banner_len, "IMU%u: fast sampling enabled %.1fkHz",
            gyro_instance, backend_rate_hz * 0.001);
        return true;
    }
    return false;
}

/*
  publish any pending data
 */
bool AP_InertialSensor_Invensensev3::update()
{
    update_accel(accel_instance);
    update_gyro(gyro_instance);
    _publish_temperature(accel_instance, temp_filtered);

    return true;
}

/*
  accumulate new samples
 */
void AP_InertialSensor_Invensensev3::accumulate()
{
    // nothing to do
}

bool AP_InertialSensor_Invensensev3::accumulate_samples(const FIFOData *data, uint8_t n_samples)
{
    for (uint8_t i = 0; i < n_samples; i++) {
        const FIFOData &d = data[i];

        // we have a header to confirm we don't have FIFO corruption! no more mucking
        // about with the temperature registers
        if ((d.header & 0xFC) != 0x68) {
            // no or bad data
            return false;
        }

        Vector3f accel{float(d.accel[0]), float(d.accel[1]), float(d.accel[2])};
        Vector3f gyro{float(d.gyro[0]), float(d.gyro[1]), float(d.gyro[2])};

        accel *= accel_scale;
        gyro *= GYRO_SCALE;
        const float temp = d.temperature * temp_sensitivity + temp_zero;

        // these four calls are about 40us
        _rotate_and_correct_accel(accel_instance, accel);
        _rotate_and_correct_gyro(gyro_instance, gyro);

        _notify_new_accel_raw_sample(accel_instance, accel, 0);
        _notify_new_gyro_raw_sample(gyro_instance, gyro);

        temp_filtered = temp_filter.apply(temp);
    }
    return true;
}

/*
  timer function called at ODR rate
 */
void AP_InertialSensor_Invensensev3::read_fifo()
{
    bool need_reset = false;
    uint16_t n_samples;

    const uint8_t reg_counth = (inv3_type == Invensensev3_Type::ICM42670)?INV3REG_70_FIFO_COUNTH:INV3REG_FIFO_COUNTH;
    const uint8_t reg_data   = (inv3_type == Invensensev3_Type::ICM42670)?INV3REG_70_FIFO_DATA:INV3REG_FIFO_DATA;
    if (!block_read(reg_counth, (uint8_t*)&n_samples, 2)) {
        goto check_registers;
    }

    if (n_samples == 0) {
        /* Not enough data in FIFO */
        goto check_registers;
    }

    // adjust the periodic callback to be synchronous with the incoming data
    // this means that we rarely run read_fifo() without updating the sensor data
    dev->adjust_periodic_callback(periodic_handle, backend_period_us);

    while (n_samples > 0) {
        uint8_t n = MIN(n_samples, INV3_FIFO_BUFFER_LEN);
        if (!block_read(reg_data, (uint8_t*)fifo_buffer, n * INV3_SAMPLE_SIZE)) {
            goto check_registers;
        }

        if (!accumulate_samples(fifo_buffer, n)) {
            need_reset = true;
            break;
        }
        n_samples -= n;
    }

    if (need_reset) {
        fifo_reset();
    }
    
check_registers:
    // check next register value for correctness
    dev->set_speed(AP_HAL::Device::SPEED_LOW);
    AP_HAL::Device::checkreg reg;
    if (!dev->check_next_register(reg)) {
        log_register_change(dev->get_bus_id(), reg);
        _inc_gyro_error_count(gyro_instance);
        _inc_accel_error_count(accel_instance);
    }
    dev->set_speed(AP_HAL::Device::SPEED_HIGH);
}

bool AP_InertialSensor_Invensensev3::block_read(uint8_t reg, uint8_t *buf, uint32_t size)
{
    return dev->read_registers(reg, buf, size);
}

uint8_t AP_InertialSensor_Invensensev3::register_read(uint8_t reg)
{
    uint8_t val = 0;
    dev->read_registers(reg, &val, 1);
    return val;
}

void AP_InertialSensor_Invensensev3::register_write(uint8_t reg, uint8_t val, bool checked)
{
    dev->write_register(reg, val, checked);
}

/*
  read a bank register, only used on startup
 */
uint8_t AP_InertialSensor_Invensensev3::register_read_bank(uint8_t bank, uint8_t reg)
{
    if (inv3_type == Invensensev3_Type::ICM42670) {
        // the ICM42670 has a complex bank setup
        register_write(INV3REG_BLK_SEL_R, bank);
        register_write(INV3REG_MADDR_R, reg);
        hal.scheduler->delay_microseconds(10);
        const uint8_t val = register_read(INV3REG_M_R);
        hal.scheduler->delay_microseconds(10);
        register_write(INV3REG_BLK_SEL_R, 0);
        return val;
    }
    register_write(INV3REG_BANK_SEL, bank);
    const uint8_t val = register_read(reg);
    register_write(INV3REG_BANK_SEL, 0);
    return val;
}

/*
  write to a bank register. This is only used on startup, so can use
  sleeps to wait for success
 */
void AP_InertialSensor_Invensensev3::register_write_bank(uint8_t bank, uint8_t reg, uint8_t val)
{
    if (inv3_type == Invensensev3_Type::ICM42670) {
        // the ICM42670 has a complex bank setup
        register_write(INV3REG_BLK_SEL_W, bank);
        register_write(INV3REG_MADDR_W, reg);
        register_write(INV3REG_M_W, val);
        hal.scheduler->delay_microseconds(10);
        register_write(INV3REG_BLK_SEL_W, 0);
        hal.scheduler->delay_microseconds(10);
    } else {
        register_write(INV3REG_BANK_SEL, bank);
        register_write(reg, val);
        register_write(INV3REG_BANK_SEL, 0);
    }
}

/*
  set the filter frequencies and scaling

  The AAF for gyros needs to be high enough to avoid group delay and low enough to have
  (ideally) 40dB at the nyquist frequency so that noise above this is not folded into the
  range seen by ArduPilot. A reasonable approximation for the former is 1Khz and for the latter
  1/4 of the sample frequency, so for 1/4 sample frequency > 1Khz we pick 1Khz and for 1/4 sample
  frequency < 1Khz we use 1/4 sample frequency.

  The AAF for accels is set lower to minimise noise and clipping. The constraint is that the
  group delay between gyros and accels should be <5ms to avoid inertial nav errors.

  The UI filter block cannot be disabled and is fixed at ODR/4. This is a 2p filter by default
  (as is the AAF). Since the order of the UI filter does not appear to significantly affect
  group delay at higher ODRs it is left at the default. The group delay of the AAF is not documented,
  but we assume it is similar to the UI 2p performance:

  2Khz  - 0.2ms
  1Khz  - 0.4ms
  666Hz - 0.6ms
  500Hz - 0.8ms
  333Hz - 2.0ms
  190Hz - 2.4ms

  Since the UI group delay is the same for both accels and gyros we only need to consider the
  difference in group delay for the AAFs. At the highest ODR of 4Khz or 8Khz the group delay for
  gyros will be 0.4ms thus the accel AAF can safely be set to ~190Hz.
 */
void AP_InertialSensor_Invensensev3::set_filter_and_scaling(void)
{
    // 1KHz by default
    backend_rate_hz = 1000;
    uint8_t odr_config = 0x06;

    // AAF at ~1/4 of 1Khz by default for gyros- 258Hz
    // AAF at 213Hz for accels
    uint8_t aaf_delt = 6, accel_aaf_delt = 5;
    uint16_t aaf_deltsqr = 36, accel_aaf_deltsqr = 25;
    uint8_t aaf_bitshift = 10, accel_aaf_bitshift = 10;

    // limited filtering on ICM-42605
    if (inv3_type == Invensensev3_Type::ICM42605) {
        // 249Hz AAF gyros
        aaf_delt = 21;
        aaf_deltsqr = 440;
        aaf_bitshift = 6;
        // 184Hz AAF accels
        accel_aaf_delt = 16;
        accel_aaf_deltsqr = 256;
        accel_aaf_bitshift = 7;
    }

    // checked for
    // ICM-40609
    // ICM-42688
    // ICM-42605
    // IIM-42652
    if (enable_fast_sampling(accel_instance) && get_fast_sampling_rate() > 1) {
        fast_sampling = dev->bus_type() == AP_HAL::Device::BUS_TYPE_SPI;

        if (fast_sampling) {
            // constrain the gyro rate to be at least the loop rate
            uint8_t loop_limit = 1;
            if (get_loop_rate_hz() > 1000) {
                loop_limit = 2;
            }
            if (get_loop_rate_hz() > 2000) {
                loop_limit = 4;
            }
            // constrain the gyro rate to be a 2^N multiple
            uint8_t fast_sampling_rate = constrain_int16(get_fast_sampling_rate(), loop_limit, 8);

            // calculate rate we will be giving samples to the backend
            backend_rate_hz *= fast_sampling_rate;

            // limited filtering on ICM-42605
            if (inv3_type == Invensensev3_Type::ICM42605) {
                switch (fast_sampling_rate) {
                    case 2: // 2KHz
                        odr_config = 0x05;
                        // 507Hz AAF
                        aaf_delt = 47;
                        aaf_deltsqr = 2208;
                        aaf_bitshift = 4;
                        break;
                    case 4: // 4KHz
                        // 995Hz AAF
                        aaf_delt = 63;
                        aaf_deltsqr = 3968;
                        aaf_bitshift = 3;
                        odr_config = 0x04;
                        break;
                    case 8: // 8Khz
                        // 995Hz AAF
                        aaf_delt = 63;
                        aaf_deltsqr = 3968;
                        aaf_bitshift = 3;
                        odr_config = 0x03;
                        break;
                    default: // 1Khz, 334Hz AAF
                        break;
                }
            } else {
                // ICM-42688 / ICM-40609 / IIM-426525
                switch (fast_sampling_rate) {
                    case 2: // 2KHz
                        odr_config = 0x05;
                        // 536Hz AAF
                        aaf_delt = 12;
                        aaf_deltsqr = 144;
                        aaf_bitshift = 8;
                        break;
                    case 4: // 4KHz
                        odr_config = 0x04;
                        // 997Hz AAF
                        aaf_delt = 21;
                        aaf_deltsqr = 440;
                        aaf_bitshift = 6;
                        break;
                    case 8: // 8Khz
                        odr_config = 0x03;
                        // 997Hz AAF
                        aaf_delt = 21;
                        aaf_deltsqr = 440;
                        aaf_bitshift = 6;
                        break;
                    default: // 1KHz, 348Hz AAF
                        break;
                }
            }
        }
    }

    // enable gyro and accel in low-noise modes
    register_write(INV3REG_PWR_MGMT0, 0x0F);
    hal.scheduler->delay_microseconds(300);

    // setup gyro for backend rate
    register_write(INV3REG_GYRO_CONFIG0, odr_config);
    // setup accel for backend rate
    register_write(INV3REG_ACCEL_CONFIG0, odr_config);

    // setup anti-alias filters for gyro at 1/4 ODR, notch left at default
    register_write_bank(1, INV3REG_GYRO_CONFIG_STATIC3, aaf_delt);   // GYRO_AAF_DELT
    register_write_bank(1, INV3REG_GYRO_CONFIG_STATIC4, (aaf_deltsqr & 0xFF)); // GYRO_AAF_DELTSQR
    register_write_bank(1, INV3REG_GYRO_CONFIG_STATIC5, ((aaf_bitshift<<4) & 0xF0) | ((aaf_deltsqr>>8) & 0x0F)); // GYRO_AAF_BITSHIFT | GYRO_AAF_DELTSQR

    // setup accel AAF at fixed ~500Hz
    register_write_bank(2, INV3REG_ACCEL_CONFIG_STATIC2, accel_aaf_delt<<1); // ACCEL_AAF_DELT | enabled bit
    register_write_bank(2, INV3REG_ACCEL_CONFIG_STATIC3, (accel_aaf_deltsqr & 0xFF)); // ACCEL_AAF_DELTSQR
    register_write_bank(2, INV3REG_ACCEL_CONFIG_STATIC4, ((accel_aaf_bitshift<<4) & 0xF0) | ((accel_aaf_deltsqr>>8) & 0x0F)); // ACCEL_AAF_BITSHIFT | ACCEL_AAF_DELTSQR
}

/*
  set the filter frequencies and scaling for the ICM-42670
 */
void AP_InertialSensor_Invensensev3::set_filter_and_scaling_icm42670(void)
{
    backend_rate_hz = 1600;
    // use low-noise mode
    register_write(INV3REG_70_PWR_MGMT0, 0x0f);
    hal.scheduler->delay_microseconds(300);

    // setup gyro for 1.6kHz, 2000dps range
    register_write(INV3REG_70_GYRO_CONFIG0, 0x05);
    // Low noise mode uses an AAF with fixed bandwidth, so disable LPF
    register_write(INV3REG_70_GYRO_CONFIG1, 0x30);

    // setup accel for 1.6kHz, 16g range
    register_write(INV3REG_70_ACCEL_CONFIG0, 0x05);
    // AAF is not available for accels, so LPF at 180Hz
    register_write(INV3REG_70_ACCEL_CONFIG1, 0x01);
}

/*
  check whoami for sensor type
 */
bool AP_InertialSensor_Invensensev3::check_whoami(void)
{
    uint8_t whoami = register_read(INV3REG_WHOAMI);

    switch (whoami) {
    case INV3_ID_ICM40609:
        inv3_type = Invensensev3_Type::ICM40609;
        accel_scale = (GRAVITY_MSS / 1024);
        return true;
    case INV3_ID_ICM42688:
        inv3_type = Invensensev3_Type::ICM42688;
        accel_scale = (GRAVITY_MSS / 2048);
        return true;
    case INV3_ID_ICM42605:
        inv3_type = Invensensev3_Type::ICM42605;
        accel_scale = (GRAVITY_MSS / 2048);
        return true;
    case INV3_ID_ICM40605:
        inv3_type = Invensensev3_Type::ICM40605;
        accel_scale = (GRAVITY_MSS / 2048);
        return true;
    case INV3_ID_IIM42652:
        inv3_type = Invensensev3_Type::IIM42652;
        accel_scale = (GRAVITY_MSS / 2048);
        return true;
    case INV3_ID_ICM42670:
        inv3_type = Invensensev3_Type::ICM42670;
        accel_scale = (GRAVITY_MSS / 2048);
        return true;
    }
    // not a value WHOAMI result
    return false;
}

bool AP_InertialSensor_Invensensev3::hardware_init(void)
{
    WITH_SEMAPHORE(dev->get_semaphore());

    dev->setup_checked_registers(7, dev->bus_type() == AP_HAL::Device::BUS_TYPE_I2C?200:20);

    // initially run the bus at low speed
    dev->set_speed(AP_HAL::Device::SPEED_LOW);

    if (!check_whoami()) {
        return false;
    }

    dev->set_speed(AP_HAL::Device::SPEED_HIGH);

    switch (inv3_type) {
    case Invensensev3_Type::ICM40609:
        _clip_limit = 29.5f * GRAVITY_MSS;
        break;
    case Invensensev3_Type::ICM42688:
    case Invensensev3_Type::IIM42652:
    case Invensensev3_Type::ICM42605:
    case Invensensev3_Type::ICM40605:
    case Invensensev3_Type::ICM42670:
        _clip_limit = 15.5f * GRAVITY_MSS;
        break;
    }

    if (inv3_type == Invensensev3_Type::ICM42670) {
        // the ICM-42670 needs some more power-up config
        for (uint8_t tries=0; tries<50; tries++) {
            // initiate a power up sequence
            register_write(INV3REG_70_SIGNAL_PATH_RESET, 0x10);
            hal.scheduler->delay_microseconds(1000);
            register_write(INV3REG_70_PWR_MGMT0, 0x0f, true);
            if (register_read(INV3REG_70_MCLK_RDY) != 0) {
                break;
            }
            hal.scheduler->delay(5);
        }
        if (register_read(INV3REG_70_MCLK_RDY) == 0) {
            return false;
        }

        // disable APEX for larger FIFO
        register_write_bank(INV3REG_BANK_MREG1, INV3REG_MREG1_SENSOR_CONFIG3, 0x40);

        // use 16 bit data, gyro+accel
        register_write_bank(INV3REG_BANK_MREG1, INV3REG_MREG1_FIFO_CONFIG5, 0x3);

        // FIFO stop-on-full, disable bypass
        register_write(INV3REG_70_FIFO_CONFIG1, 0x2, true);
        
        // little-endian, fifo count in records
        register_write(INV3REG_70_INTF_CONFIG0, 0x40, true);
    }

    return true;
}