mpu9250.cpp

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/**
 * @file mpu9250.cpp
 *
 * Driver for the Invensense MPU9250 connected via I2C or SPI.
 *
 * @author Andrew Tridgell
 *
 * based on the mpu6000 driver
 */

#include "mpu9250.h"

/*
  we set the timer interrupt to run a bit faster than the desired
  sample rate and then throw away duplicates by comparing
  accelerometer values. This time reduction is enough to cope with
  worst case timing jitter due to other timers
 */
#define MPU9250_TIMER_REDUCTION             200

/* Set accel range used */
#define ACCEL_RANGE_G  16
/*
  list of registers that will be checked in check_registers(). Note
  that MPUREG_PRODUCT_ID must be first in the list.
 */
const uint16_t MPU9250::_mpu9250_checked_registers[MPU9250_NUM_CHECKED_REGISTERS] = { MPUREG_WHOAMI,
                                              MPUREG_PWR_MGMT_1,
                                              MPUREG_PWR_MGMT_2,
                                              MPUREG_USER_CTRL,
                                              MPUREG_SMPLRT_DIV,
                                              MPUREG_CONFIG,
                                              MPUREG_GYRO_CONFIG,
                                              MPUREG_ACCEL_CONFIG,
                                              MPUREG_ACCEL_CONFIG2,
                                              MPUREG_INT_ENABLE,
                                              MPUREG_INT_PIN_CFG
                                            };

MPU9250::MPU9250(device::Device *interface, device::Device *mag_interface, enum Rotation rotation) :
    ScheduledWorkItem(MODULE_NAME, px4::device_bus_to_wq(interface->get_device_id())),
    _interface(interface),
    _px4_accel(_interface->get_device_id(), (_interface->external() ? ORB_PRIO_MAX : ORB_PRIO_HIGH), rotation),
    _px4_gyro(_interface->get_device_id(), (_interface->external() ? ORB_PRIO_MAX : ORB_PRIO_HIGH), rotation),
    _mag(this, mag_interface, rotation),
    _dlpf_freq(MPU9250_DEFAULT_ONCHIP_FILTER_FREQ),
    _sample_perf(perf_alloc(PC_ELAPSED, MODULE_NAME": read")),
    _bad_transfers(perf_alloc(PC_COUNT, MODULE_NAME": bad_trans")),
    _bad_registers(perf_alloc(PC_COUNT, MODULE_NAME": bad_reg")),
    _good_transfers(perf_alloc(PC_COUNT, MODULE_NAME": good_trans")),
    _duplicates(perf_alloc(PC_COUNT, MODULE_NAME": dupe"))
{
    _px4_accel.set_device_type(DRV_ACC_DEVTYPE_MPU9250);
    _px4_gyro.set_device_type(DRV_GYR_DEVTYPE_MPU9250);
}

MPU9250::~MPU9250()
{
    // make sure we are truly inactive
    stop();

    // delete the perf counter
    perf_free(_sample_perf);
    perf_free(_bad_transfers);
    perf_free(_bad_registers);
    perf_free(_good_transfers);
    perf_free(_duplicates);
}

int
MPU9250::init()
{
    /*
     * If the MPU is using I2C we should reduce the sample rate to 200Hz and
     * make the integration autoreset faster so that we integrate just one
     * sample since the sampling rate is already low.
    */
    const bool is_i2c = (_interface->get_device_bus_type() == device::Device::DeviceBusType_I2C);

    if (is_i2c) {
        _sample_rate = 200;
    }

    int ret = probe();

    if (ret != OK) {
        PX4_DEBUG("probe failed");
        return ret;
    }

    _reset_wait = hrt_absolute_time() + 100000;

    if (reset_mpu() != OK) {
        PX4_ERR("Exiting! Device failed to take initialization");
        return ret;
    }

    /* Magnetometer setup */
    if (_whoami == MPU_WHOAMI_9250) {

#ifdef USE_I2C
        px4_usleep(100);

        if (!_mag.is_passthrough() && _mag._interface->init() != PX4_OK) {
            PX4_ERR("failed to setup ak8963 interface");
        }

#endif /* USE_I2C */

        ret = _mag.ak8963_reset();

        if (ret != OK) {
            PX4_DEBUG("mag reset failed");
            return ret;
        }
    }

    start();

    return ret;
}

int
MPU9250::reset()
{
    /* When the mpu9250 starts from 0V the internal power on circuit
     * per the data sheet will require:
     *
     * Start-up time for register read/write From power-up Typ:11 max:100 ms
     *
     */
    px4_usleep(110000);

    // Hold off sampling until done (100 MS will be shortened)
    _reset_wait = hrt_absolute_time() + 100000;

    int ret = reset_mpu();

    if (ret == OK && (_whoami == MPU_WHOAMI_9250)) {
        ret = _mag.ak8963_reset();
    }

    _reset_wait = hrt_absolute_time() + 10;

    return ret;
}

int
MPU9250::reset_mpu()
{
    switch (_whoami) {
    case MPU_WHOAMI_9250:
    case MPU_WHOAMI_6500:
        write_reg(MPUREG_PWR_MGMT_1, BIT_H_RESET);
        write_checked_reg(MPUREG_PWR_MGMT_1, MPU_CLK_SEL_AUTO);
        write_checked_reg(MPUREG_PWR_MGMT_2, 0);
        px4_usleep(1000);
        break;
    }

    // Enable I2C bus or Disable I2C bus (recommended on data sheet)
    const bool is_i2c = (_interface->get_device_bus_type() == device::Device::DeviceBusType_I2C);
    write_checked_reg(MPUREG_USER_CTRL, is_i2c ? 0 : BIT_I2C_IF_DIS);

    // SAMPLE RATE
    _set_sample_rate(_sample_rate);

    _set_dlpf_filter(MPU9250_DEFAULT_ONCHIP_FILTER_FREQ);

    // Gyro scale 2000 deg/s ()
    switch (_whoami) {
    case MPU_WHOAMI_9250:
    case MPU_WHOAMI_6500:
        write_checked_reg(MPUREG_GYRO_CONFIG, BITS_FS_2000DPS);
        break;
    }

    // correct gyro scale factors
    // scale to rad/s in SI units
    // 2000 deg/s = (2000/180)*PI = 34.906585 rad/s
    // scaling factor:
    // 1/(2^15)*(2000/180)*PI
    _px4_gyro.set_scale(0.0174532 / 16.4); //1.0f / (32768.0f * (2000.0f / 180.0f) * M_PI_F);

    set_accel_range(ACCEL_RANGE_G);

    // INT CFG => Interrupt on Data Ready
    write_checked_reg(MPUREG_INT_ENABLE, BIT_RAW_RDY_EN);        // INT: Raw data ready

#ifdef USE_I2C
    bool bypass = !_mag.is_passthrough();
#else
    bool bypass = false;
#endif

    /* INT: Clear on any read.
     * If this instance is for a device is on I2C bus the Mag will have an i2c interface
     * that it will use to access the either: a) the internal mag device on the internal I2C bus
     * or b) it could be used to access a downstream I2C devices connected to the chip on
     * it's AUX_{ASD|SCL} pins. In either case we need to disconnect (bypass) the internal master
     * controller that chip provides as a SPI to I2C bridge.
     * so bypass is true if the mag has an i2c non null interfaces.
     */

    write_checked_reg(MPUREG_INT_PIN_CFG, BIT_INT_ANYRD_2CLEAR | (bypass ? BIT_INT_BYPASS_EN : 0));

    write_checked_reg(MPUREG_ACCEL_CONFIG2, BITS_ACCEL_CONFIG2_41HZ);

    uint8_t retries = 3;
    bool all_ok = false;

    while (!all_ok && retries--) {

        // Assume all checked values are as expected
        all_ok = true;
        uint8_t reg = 0;

        for (uint8_t i = 0; i < _num_checked_registers; i++) {
            if ((reg = read_reg(_checked_registers[i])) != _checked_values[i]) {

                write_reg(_checked_registers[i], _checked_values[i]);
                PX4_ERR("Reg %d is:%d s/b:%d Tries:%d", _checked_registers[i], reg, _checked_values[i], retries);
                all_ok = false;
            }
        }
    }

    return all_ok ? OK : -EIO;
}

int
MPU9250::probe()
{
    int ret = PX4_ERROR;

    // Try first for mpu9250/6500
    _whoami = read_reg(MPUREG_WHOAMI);

    if (_whoami == MPU_WHOAMI_9250 || _whoami == MPU_WHOAMI_6500) {

        _num_checked_registers = MPU9250_NUM_CHECKED_REGISTERS;
        _checked_registers = _mpu9250_checked_registers;
        memset(_checked_values, 0, MPU9250_NUM_CHECKED_REGISTERS);
        memset(_checked_bad, 0, MPU9250_NUM_CHECKED_REGISTERS);
        ret = PX4_OK;
    }

    _checked_values[0] = _whoami;
    _checked_bad[0] = _whoami;

    if (ret != PX4_OK) {
        PX4_DEBUG("unexpected whoami 0x%02x", _whoami);
    }

    return ret;
}

/*
  set sample rate (approximate) - 1kHz to 5Hz, for both accel and gyro
*/
void
MPU9250::_set_sample_rate(unsigned desired_sample_rate_hz)
{
    uint8_t div = 1;

    if (desired_sample_rate_hz == 0) {
        desired_sample_rate_hz = MPU9250_GYRO_DEFAULT_RATE;
    }

    switch (_whoami) {
    case MPU_WHOAMI_9250:
    case MPU_WHOAMI_6500:
        div = 1000 / desired_sample_rate_hz;
        break;
    }

    if (div > 200) { div = 200; }

    if (div < 1) { div = 1; }


    switch (_whoami) {
    case MPU_WHOAMI_9250:
    case MPU_WHOAMI_6500:
        write_checked_reg(MPUREG_SMPLRT_DIV, div - 1);
        _sample_rate = 1000 / div;
        break;
    }
}

/*
  set the DLPF filter frequency. This affects both accel and gyro.
 */
void
MPU9250::_set_dlpf_filter(uint16_t frequency_hz)
{
    uint8_t filter;

    switch (_whoami) {
    case MPU_WHOAMI_9250:
    case MPU_WHOAMI_6500:

        /*
           choose next highest filter frequency available
         */
        if (frequency_hz == 0) {
            _dlpf_freq = 0;
            filter = BITS_DLPF_CFG_3600HZ;

        } else if (frequency_hz <= 5) {
            _dlpf_freq = 5;
            filter = BITS_DLPF_CFG_5HZ;

        } else if (frequency_hz <= 10) {
            _dlpf_freq = 10;
            filter = BITS_DLPF_CFG_10HZ;

        } else if (frequency_hz <= 20) {
            _dlpf_freq = 20;
            filter = BITS_DLPF_CFG_20HZ;

        } else if (frequency_hz <= 41) {
            _dlpf_freq = 41;
            filter = BITS_DLPF_CFG_41HZ;

        } else if (frequency_hz <= 92) {
            _dlpf_freq = 92;
            filter = BITS_DLPF_CFG_92HZ;

        } else if (frequency_hz <= 184) {
            _dlpf_freq = 184;
            filter = BITS_DLPF_CFG_184HZ;

        } else if (frequency_hz <= 250) {
            _dlpf_freq = 250;
            filter = BITS_DLPF_CFG_250HZ;

        } else {
            _dlpf_freq = 0;
            filter = BITS_DLPF_CFG_3600HZ;
        }

        write_checked_reg(MPUREG_CONFIG, filter);
        break;
    }
}

uint8_t
MPU9250::read_reg(unsigned reg, uint32_t speed)
{
    uint8_t buf{};

    _interface->read(MPU9250_SET_SPEED(reg, speed), &buf, 1);

    return buf;
}

uint8_t
MPU9250::read_reg_range(unsigned start_reg, uint32_t speed, uint8_t *buf, uint16_t count)
{
    if (buf == NULL) {
        return PX4_ERROR;
    }

    return _interface->read(MPU9250_SET_SPEED(start_reg, speed), buf, count);
}

uint16_t
MPU9250::read_reg16(unsigned reg)
{
    uint8_t buf[2] {};

    // general register transfer at low clock speed
    _interface->read(MPU9250_LOW_SPEED_OP(reg), &buf, arraySize(buf));

    return (uint16_t)(buf[0] << 8) | buf[1];
}

void
MPU9250::write_reg(unsigned reg, uint8_t value)
{
    // general register transfer at low clock speed
    _interface->write(MPU9250_LOW_SPEED_OP(reg), &value, 1);
}

void
MPU9250::modify_reg(unsigned reg, uint8_t clearbits, uint8_t setbits)
{
    uint8_t val = read_reg(reg);
    val &= ~clearbits;
    val |= setbits;
    write_reg(reg, val);
}

void
MPU9250::modify_checked_reg(unsigned reg, uint8_t clearbits, uint8_t setbits)
{
    uint8_t val = read_reg(reg);
    val &= ~clearbits;
    val |= setbits;
    write_checked_reg(reg, val);
}

void
MPU9250::write_checked_reg(unsigned reg, uint8_t value)
{
    write_reg(reg, value);

    for (uint8_t i = 0; i < _num_checked_registers; i++) {
        if (reg == _checked_registers[i]) {
            _checked_values[i] = value;
            _checked_bad[i] = value;
            break;
        }
    }
}

int
MPU9250::set_accel_range(unsigned max_g_in)
{
    uint8_t afs_sel;
    float lsb_per_g;
    //float max_accel_g;

    if (max_g_in > 8) { // 16g - AFS_SEL = 3
        afs_sel = 3;
        lsb_per_g = 2048;
        //max_accel_g = 16;

    } else if (max_g_in > 4) { //  8g - AFS_SEL = 2
        afs_sel = 2;
        lsb_per_g = 4096;
        //max_accel_g = 8;

    } else if (max_g_in > 2) { //  4g - AFS_SEL = 1
        afs_sel = 1;
        lsb_per_g = 8192;
        //max_accel_g = 4;

    } else {                //  2g - AFS_SEL = 0
        afs_sel = 0;
        lsb_per_g = 16384;
        //max_accel_g = 2;
    }

    switch (_whoami) {
    case MPU_WHOAMI_9250:
    case MPU_WHOAMI_6500:
        write_checked_reg(MPUREG_ACCEL_CONFIG, afs_sel << 3);
        break;
    }

    _px4_accel.set_scale(CONSTANTS_ONE_G / lsb_per_g);

    return OK;
}

void
MPU9250::start()
{
    /* make sure we are stopped first */
    stop();

    ScheduleOnInterval(_call_interval - MPU9250_TIMER_REDUCTION, 1000);
}

void
MPU9250::stop()
{
    ScheduleClear();
}

void
MPU9250::Run()
{
    /* make another measurement */
    measure();
}

void
MPU9250::check_registers()
{
    /*
      we read the register at full speed, even though it isn't
      listed as a high speed register. The low speed requirement
      for some registers seems to be a propagation delay
      requirement for changing sensor configuration, which should
      not apply to reading a single register. It is also a better
      test of SPI bus health to read at the same speed as we read
      the data registers.
    */
    uint8_t v = 0;

    if ((v = read_reg(_checked_registers[_checked_next], MPU9250_HIGH_BUS_SPEED)) != _checked_values[_checked_next]) {

        _checked_bad[_checked_next] = v;

        /*
          if we get the wrong value then we know the SPI bus
          or sensor is very sick. We set _register_wait to 20
          and wait until we have seen 20 good values in a row
          before we consider the sensor to be OK again.
         */
        perf_count(_bad_registers);

        /*
          try to fix the bad register value. We only try to
          fix one per loop to prevent a bad sensor hogging the
          bus.
         */
        if (_register_wait == 0 || _checked_next == 0) {
            // if the product_id is wrong then reset the sensor completely
            write_reg(MPUREG_PWR_MGMT_1, BIT_H_RESET);
            write_reg(MPUREG_PWR_MGMT_2, MPU_CLK_SEL_AUTO);

            // after doing a reset we need to wait a long
            // time before we do any other register writes
            // or we will end up with the mpu9250 in a
            // bizarre state where it has all correct
            // register values but large offsets on the
            // accel axes
            _reset_wait = hrt_absolute_time() + 10000;
            _checked_next = 0;

        } else {
            write_reg(_checked_registers[_checked_next], _checked_values[_checked_next]);

            // waiting 3ms between register writes seems
            // to raise the chance of the sensor
            // recovering considerably
            _reset_wait = hrt_absolute_time() + 3000;
        }

        _register_wait = 20;
    }

    _checked_next = (_checked_next + 1) % _num_checked_registers;
}

bool
MPU9250::check_null_data(uint16_t *data, uint8_t size)
{
    while (size--) {
        if (*data++) {
            perf_count(_good_transfers);
            return false;
        }
    }

    // all zero data - probably a SPI bus error
    perf_count(_bad_transfers);
    perf_end(_sample_perf);
    // note that we don't call reset() here as a reset()
    // costs 20ms with interrupts disabled. That means if
    // the mpu9250 does go bad it would cause a FMU failure,
    // regardless of whether another sensor is available,
    return true;
}

bool
MPU9250::check_duplicate(uint8_t *accel_data)
{
    /*
       see if this is duplicate accelerometer data. Note that we
       can't use the data ready interrupt status bit in the status
       register as that also goes high on new gyro data, and when
       we run with BITS_DLPF_CFG_256HZ_NOLPF2 the gyro is being
       sampled at 8kHz, so we would incorrectly think we have new
       data when we are in fact getting duplicate accelerometer data.
    */
    if (!_got_duplicate && memcmp(accel_data, &_last_accel_data, sizeof(_last_accel_data)) == 0) {
        // it isn't new data - wait for next timer
        perf_end(_sample_perf);
        perf_count(_duplicates);
        _got_duplicate = true;

    } else {
        memcpy(&_last_accel_data, accel_data, sizeof(_last_accel_data));
        _got_duplicate = false;
    }

    return _got_duplicate;
}

void
MPU9250::measure()
{
    perf_begin(_sample_perf);

    if (hrt_absolute_time() < _reset_wait) {
        // we're waiting for a reset to complete
        perf_end(_sample_perf);
        return;
    }

    MPUReport mpu_report{};

    struct Report {
        int16_t     accel_x;
        int16_t     accel_y;
        int16_t     accel_z;
        int16_t     temp;
        int16_t     gyro_x;
        int16_t     gyro_y;
        int16_t     gyro_z;
    } report{};

    const hrt_abstime timestamp_sample = hrt_absolute_time();

    // Fetch the full set of measurements from the ICM20948 in one pass
    if (_mag.is_passthrough() && _register_wait == 0) {
        if (_whoami == MPU_WHOAMI_9250 || _whoami == MPU_WHOAMI_6500) {
            if (OK != read_reg_range(MPUREG_INT_STATUS, MPU9250_HIGH_BUS_SPEED, (uint8_t *)&mpu_report, sizeof(mpu_report))) {
                perf_end(_sample_perf);
                return;
            }
        }

        check_registers();

        if (check_duplicate(&mpu_report.accel_x[0])) {
            return;
        }
    }

    /*
     * In case of a mag passthrough read, hand the magnetometer data over to _mag. Else,
     * try to read a magnetometer report.
     */

#   ifdef USE_I2C

    if (_mag.is_passthrough()) {
#   endif

        if (_register_wait == 0) {
            _mag._measure(timestamp_sample, mpu_report.mag);
        }

#   ifdef USE_I2C

    } else {
        _mag.measure();
    }

#   endif

    // Continue evaluating gyro and accelerometer results
    if (_register_wait == 0) {
        // Convert from big to little endian
        report.accel_x = int16_t_from_bytes(mpu_report.accel_x);
        report.accel_y = int16_t_from_bytes(mpu_report.accel_y);
        report.accel_z = int16_t_from_bytes(mpu_report.accel_z);
        report.temp    = int16_t_from_bytes(mpu_report.temp);
        report.gyro_x  = int16_t_from_bytes(mpu_report.gyro_x);
        report.gyro_y  = int16_t_from_bytes(mpu_report.gyro_y);
        report.gyro_z  = int16_t_from_bytes(mpu_report.gyro_z);

        if (check_null_data((uint16_t *)&report, sizeof(report) / 2)) {
            return;
        }
    }

    if (_register_wait != 0) {
        /*
         * We are waiting for some good transfers before using the sensor again.
         * We still increment _good_transfers, but don't return any data yet.
        */
        _register_wait--;
        return;
    }

    // Get sensor temperature
    _last_temperature = (report.temp) / 333.87f + 21.0f;

    _px4_accel.set_temperature(_last_temperature);
    _px4_gyro.set_temperature(_last_temperature);


    // Swap axes and negate y
    int16_t accel_xt = report.accel_y;
    int16_t accel_yt = ((report.accel_x == -32768) ? 32767 : -report.accel_x);

    int16_t gyro_xt = report.gyro_y;
    int16_t gyro_yt = ((report.gyro_x == -32768) ? 32767 : -report.gyro_x);

    // Apply the swap
    report.accel_x = accel_xt;
    report.accel_y = accel_yt;
    report.gyro_x = gyro_xt;
    report.gyro_y = gyro_yt;

    // report the error count as the sum of the number of bad
    // transfers and bad register reads. This allows the higher
    // level code to decide if it should use this sensor based on
    // whether it has had failures
    const uint64_t error_count = perf_event_count(_bad_transfers) + perf_event_count(_bad_registers);
    _px4_accel.set_error_count(error_count);
    _px4_gyro.set_error_count(error_count);

    /* NOTE: Axes have been swapped to match the board a few lines above. */
    _px4_accel.update(timestamp_sample, report.accel_x, report.accel_y, report.accel_z);
    _px4_gyro.update(timestamp_sample, report.gyro_x, report.gyro_y, report.gyro_z);

    /* stop measuring */
    perf_end(_sample_perf);
}

void
MPU9250::print_info()
{
    perf_print_counter(_sample_perf);
    perf_print_counter(_bad_transfers);
    perf_print_counter(_bad_registers);
    perf_print_counter(_good_transfers);
    perf_print_counter(_duplicates);

    _px4_accel.print_status();
    _px4_gyro.print_status();
    _mag.print_status();
}