ardupilot/libraries/AP_Compass/AP_Compass_IST8310.cpp

/*
 * Copyright (C) 2016  Emlid Ltd. 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/>.
 *
 * Driver by Georgii Staroselskii, Sep 2016
 */
#include "AP_Compass_IST8310.h"

#include <stdio.h>
#include <utility>

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

#define WAI_REG 0x0
#define DEVICE_ID 0x10

#define CNTL1_REG 0xA
#define SINGLE_MEASUREMENT_MODE 0x1
#define ODR_100HZ 0x6

#define STAT1_REG 0x2
#define DATA_RDY 0x1

#define AVGCNTL_REG 0x41
#define AVERAGING_Y_BY_2 0x20
#define AVERAGING_XZ_BY_4 0x04

#define PDCNTL_REG 0x42
#define NORMAL_PULSE_DURATION 0xC0

extern const AP_HAL::HAL &hal;

AP_Compass_Backend *AP_Compass_IST8310::probe(Compass &compass,
                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                              enum Rotation rotation)
{
    if (!dev) {
        return nullptr;
    }

    AP_Compass_IST8310 *sensor = new AP_Compass_IST8310(compass, std::move(dev), rotation);
    if (!sensor || !sensor->init()) {
        delete sensor;
        return nullptr;
    }

    return sensor;
}

AP_Compass_IST8310::AP_Compass_IST8310(Compass &compass,
                                       AP_HAL::OwnPtr<AP_HAL::Device> dev,
                                       enum Rotation rotation)
    : AP_Compass_Backend(compass)
    , _dev(std::move(dev))
    , _rotation(rotation)
{
}

bool AP_Compass_IST8310::init()
{
    if (!_dev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
        return false;
    }

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

    uint8_t whoami;
    if (!_dev->read_registers(WAI_REG, &whoami, 1) ||
        whoami != DEVICE_ID) {
        // not an IST8310
        goto fail;
    }

    if (!_dev->write_register(AVGCNTL_REG, AVERAGING_Y_BY_2 | AVERAGING_XZ_BY_4) ||
        !_dev->write_register(PDCNTL_REG, NORMAL_PULSE_DURATION)) {
        fprintf(stderr, "IST8310: found device but could not set it up\n");
        goto fail;
    }

    // lower retries for run
    _dev->set_retries(3);

    // start state machine: request a sample
    start_conversion();

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

    _instance = register_compass();

    printf("%s found on bus %u id %u address 0x%02x\n", name,
           _dev->bus_num(), _dev->get_bus_id(), _dev->get_bus_address());

    set_rotation(_instance, _rotation);

    _dev->set_device_type(DEVTYPE_IST8310);
    set_dev_id(_instance, _dev->get_bus_id());

    _dev->register_periodic_callback(10 * USEC_PER_MSEC,
                                     FUNCTOR_BIND_MEMBER(&AP_Compass_IST8310::timer, void));

    return true;

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

void AP_Compass_IST8310::start_conversion()
{
    _dev->write_register(CNTL1_REG,
            SINGLE_MEASUREMENT_MODE);
}

void AP_Compass_IST8310::timer()
{
    bool ret = false;

    struct PACKED {
        uint8_t status;
        le16_t rx;
        le16_t ry;
        le16_t rz;
    } buffer;


    ret = _dev->read_registers(STAT1_REG, (uint8_t *) &buffer, sizeof(buffer));
    if (!ret) {
        /* We're going to be back on the next iteration either way */
        return;
    }

    auto status = buffer.status;

    if (!(status & 0x01)) {
        /* We're not ready yet */
       return;
    }

    auto x = static_cast<int16_t>(le16toh(buffer.rx));
    auto y = static_cast<int16_t>(le16toh(buffer.ry));
    auto z = static_cast<int16_t>(le16toh(buffer.rz));

    /* convert uT to milligauss */
    Vector3f field = Vector3f{x * 3.0f, y * 3.0f, z * 3.0f};

    /* rotate raw_field from sensor frame to body frame */
    rotate_field(field, _instance);

    /* publish raw_field (uncorrected point sample) for calibration use */
    publish_raw_field(field, AP_HAL::micros(), _instance);

    /* correct raw_field for known errors */
    correct_field(field, _instance);

    if (_sem->take(0)) {
        _accum += field;
        _accum_count++;
        _sem->give();
    }

    start_conversion();
}

void AP_Compass_IST8310::read()
{
    if (!_sem->take_nonblocking()) {
        return;
    }

    if (_accum_count == 0) {
        _sem->give();
        return;
    }

    Vector3f field(_accum);
    field /= _accum_count;

    publish_filtered_field(field, _instance);

    _accum.zero();
    _accum_count = 0;

    _sem->give();
}