ardupilot/libraries/AP_Compass/AP_Compass_BMM150.cpp

/*
 * Copyright (C) 2016  Intel Corporation. All rights reserved.
 *
 * This file 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 file 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/>.
 */
#include "AP_Compass_BMM150.h"

#if AP_COMPASS_BMM150_ENABLED

#include <AP_HAL/AP_HAL.h>

#include <utility>

#include <AP_HAL/utility/sparse-endian.h>
#include <AP_Math/AP_Math.h>
#include <stdio.h>

#define CHIP_ID_REG 0x40
#define CHIP_ID_VAL 0x32

#define POWER_AND_OPERATIONS_REG 0x4B
#define POWER_CONTROL_VAL (1 << 0)
#define SOFT_RESET (1 << 7 | 1 << 1)

#define OP_MODE_SELF_TEST_ODR_REG 0x4C
#define NORMAL_MODE (0 << 1)
#define ODR_30HZ (1 << 3 | 1 << 4 | 1 << 5)
#define ODR_20HZ (1 << 3 | 0 << 4 | 1 << 5)

#define DATA_X_LSB_REG 0x42

#define REPETITIONS_XY_REG 0x51
#define REPETITIONS_Z_REG 0X52

/* Trim registers */
#define DIG_X1_REG 0x5D
#define DIG_Y1_REG 0x5E
#define DIG_Z4_LSB_REG 0x62
#define DIG_Z4_MSB_REG 0x63
#define DIG_X2_REG 0x64
#define DIG_Y2_REG 0x65
#define DIG_Z2_LSB_REG 0x68
#define DIG_Z2_MSB_REG 0x69
#define DIG_Z1_LSB_REG 0x6A
#define DIG_Z1_MSB_REG 0x6B
#define DIG_XYZ1_LSB_REG 0x6C
#define DIG_XYZ1_MSB_REG 0x6D
#define DIG_Z3_LSB_REG 0x6E
#define DIG_Z3_MSB_REG 0x6F
#define DIG_XY2_REG 0x70
#define DIG_XY1_REG 0x71

#define MEASURE_TIME_USEC 16667

extern const AP_HAL::HAL &hal;

AP_Compass_Backend *AP_Compass_BMM150::probe(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev, bool force_external, enum Rotation rotation)
{
    if (!dev) {
        return nullptr;
    }
    AP_Compass_BMM150 *sensor = NEW_NOTHROW AP_Compass_BMM150(std::move(dev), force_external, rotation);
    if (!sensor || !sensor->init()) {
        delete sensor;
        return nullptr;
    }

    return sensor;
}

AP_Compass_BMM150::AP_Compass_BMM150(AP_HAL::OwnPtr<AP_HAL::Device> dev, bool force_external, enum Rotation rotation)
    : _dev(std::move(dev)), _rotation(rotation), _force_external(force_external)
{
}

bool AP_Compass_BMM150::_load_trim_values()
{
    struct {
        int8_t dig_x1;
        int8_t dig_y1;
        uint8_t rsv[3];
        le16_t dig_z4;
        int8_t dig_x2;
        int8_t dig_y2;
        uint8_t rsv2[2];
        le16_t dig_z2;
        le16_t dig_z1;
        le16_t dig_xyz1;
        le16_t dig_z3;
        int8_t dig_xy2;
        uint8_t dig_xy1;
    } PACKED trim_registers, trim_registers2;

    // read the registers twice to confirm we have the right
    // values. There is no CRC in the registers and these values are
    // vital to correct operation
    int8_t tries = 4;
    while (tries--) {
        if (!_dev->read_registers(DIG_X1_REG, (uint8_t *)&trim_registers,
                                  sizeof(trim_registers))) {
            continue;
        }
        if (!_dev->read_registers(DIG_X1_REG, (uint8_t *)&trim_registers2,
                                  sizeof(trim_registers))) {
            continue;
        }
        if (memcmp(&trim_registers, &trim_registers2, sizeof(trim_registers)) == 0) {
            break;
        }
    }
    if (-1 == tries) {
        DEV_PRINTF("BMM150: Failed to load trim registers\n");
        return false;
    }

    _dig.x1 = trim_registers.dig_x1;
    _dig.x2 = trim_registers.dig_x2;
    _dig.xy1 = trim_registers.dig_xy1;
    _dig.xy2 = trim_registers.dig_xy2;
    _dig.xyz1 = le16toh(trim_registers.dig_xyz1);
    _dig.y1 = trim_registers.dig_y1;
    _dig.y2 = trim_registers.dig_y2;
    _dig.z1 = le16toh(trim_registers.dig_z1);
    _dig.z2 = le16toh(trim_registers.dig_z2);
    _dig.z3 = le16toh(trim_registers.dig_z3);
    _dig.z4 = le16toh(trim_registers.dig_z4);

    return true;
}

bool AP_Compass_BMM150::init()
{
    uint8_t val = 0;
    bool ret;

    _dev->get_semaphore()->take_blocking();

    // 10 retries for init
    _dev->set_retries(10);

    // use checked registers to cope with bus errors
    _dev->setup_checked_registers(4);
    
    int8_t boot_tries = 4;
    while (boot_tries--) {
        /* Do a soft reset */
        ret = _dev->write_register(POWER_AND_OPERATIONS_REG, SOFT_RESET);
        hal.scheduler->delay(2);
        if (!ret) {
            continue;
        }

        /* Change power state from suspend mode to sleep mode */
        ret = _dev->write_register(POWER_AND_OPERATIONS_REG, POWER_CONTROL_VAL, true);
        hal.scheduler->delay(2);
        if (!ret) {
            continue;
        }

        ret = _dev->read_registers(CHIP_ID_REG, &val, 1);
        if (!ret) {
            continue;
        }
        if (val == CHIP_ID_VAL) {
            // found it
            break;
        }
        if (boot_tries == 0) {
            DEV_PRINTF("BMM150: Wrong chip ID 0x%02x should be 0x%02x\n", val, CHIP_ID_VAL);
        }
    }
    if (-1 == boot_tries) {
        goto bus_error;
    }

    ret = _load_trim_values();
    if (!ret) {
        goto bus_error;
    }

    /*
     * Recommended preset for high accuracy:
     * - Rep X/Y = 47
     * - Rep Z = 83
     * - ODR = 20
     * But we are going to use 30Hz of ODR
     */
    ret = _dev->write_register(REPETITIONS_XY_REG, (47 - 1) / 2, true);
    if (!ret) {
        goto bus_error;
    }
    ret = _dev->write_register(REPETITIONS_Z_REG, 83 - 1, true);
    if (!ret) {
        goto bus_error;
    }
    /* Change operation mode from sleep to normal and set ODR */
    ret = _dev->write_register(OP_MODE_SELF_TEST_ODR_REG, NORMAL_MODE | ODR_30HZ, true);
    if (!ret) {
        goto bus_error;
    }

    _dev->get_semaphore()->give();

    /* register the compass instance in the frontend */
    _dev->set_device_type(DEVTYPE_BMM150);
    if (!register_compass(_dev->get_bus_id(), _compass_instance)) {
        return false;
    }
    set_dev_id(_compass_instance, _dev->get_bus_id());

    set_rotation(_compass_instance, _rotation);

    if (_force_external) {
        set_external(_compass_instance, true);
    }

    // 2 retries for run
    _dev->set_retries(2);
    
    _dev->register_periodic_callback(MEASURE_TIME_USEC,
            FUNCTOR_BIND_MEMBER(&AP_Compass_BMM150::_update, void));

    _last_read_ms = AP_HAL::millis();
    
    return true;

bus_error:
    _dev->get_semaphore()->give();
    return false;
}

/*
 * Compensation algorithm got from https://github.com/BoschSensortec/BMM050_driver
 * this is not explained in datasheet.
 */
int16_t AP_Compass_BMM150::_compensate_xy(int16_t xy, uint32_t rhall, int32_t txy1, int32_t txy2) const
{
    int32_t inter = ((int32_t)_dig.xyz1) << 14;
    inter /= rhall;
    inter -= 0x4000;

    int32_t val = _dig.xy2 * ((inter * inter) >> 7);
    val += (inter * (((uint32_t)_dig.xy1) << 7));
    val >>= 9;
    val += 0x100000;
    val *= (txy2 + 0xA0);
    val >>= 12;
    val *= xy;
    val >>= 13;
    val += (txy1 << 3);

    return val;
}

int16_t AP_Compass_BMM150::_compensate_z(int16_t z, uint32_t rhall) const
{
    int32_t dividend = int32_t(z - _dig.z4) << 15;
    int32_t dividend2 = dividend - ((_dig.z3 * (int32_t(rhall) - int32_t(_dig.xyz1))) >> 2);

    int32_t divisor = int32_t(_dig.z1) * (rhall << 1);
    divisor += 0x8000;
    divisor >>= 16;
    divisor += _dig.z2;

    int16_t ret = constrain_int32(dividend2 / divisor, -0x8000, 0x8000);
#if 0
    static uint8_t counter;
    if (counter++ == 0) {
        printf("ret=%d z=%d rhall=%u z1=%d z2=%d z3=%d z4=%d xyz1=%d dividend=%d dividend2=%d divisor=%d\n",
               ret, z, rhall, _dig.z1, _dig.z2, _dig.z3, _dig.z4, _dig.xyz1, dividend, dividend2, divisor);
    }
#endif
    return ret;
}

void AP_Compass_BMM150::_update()
{
    le16_t data[4];
    bool ret = _dev->read_registers(DATA_X_LSB_REG, (uint8_t *) &data, sizeof(data));

    /* Checking data ready status */
    if (!ret || !(data[3] & 0x1)) {
        _dev->check_next_register();
        uint32_t now = AP_HAL::millis();
        if (now - _last_read_ms > 250) {
            // cope with power cycle to sensor
            _last_read_ms = now;
            _dev->write_register(POWER_AND_OPERATIONS_REG, SOFT_RESET);
            _dev->write_register(POWER_AND_OPERATIONS_REG, POWER_CONTROL_VAL, true);
        }
        return;
    }

    const uint16_t rhall = le16toh(data[3]) >> 2;

    Vector3f raw_field = Vector3f{
        (float) _compensate_xy(((int16_t)le16toh(data[0])) >> 3,
                               rhall, _dig.x1, _dig.x2),
        (float) _compensate_xy(((int16_t)le16toh(data[1])) >> 3,
                               rhall, _dig.y1, _dig.y2),
        (float) _compensate_z(((int16_t)le16toh(data[2])) >> 1, rhall)};

    /* apply sensitivity scale 16 LSB/uT */
    raw_field /= 16;
    /* convert uT to milligauss */
    raw_field *= 10;

    _last_read_ms = AP_HAL::millis();

    accumulate_sample(raw_field, _compass_instance);
    _dev->check_next_register();
}

void AP_Compass_BMM150::read()
{
    drain_accumulated_samples(_compass_instance);
}


#endif  // AP_COMPASS_BMM150_ENABLED