ms5611.cpp

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/**
 * @file ms5611.cpp
 * Driver for the MS5611 and MS5607 barometric pressure sensor connected via I2C or SPI.
 */

#include "MS5611.hpp"
#include "ms5611.h"

#include <cdev/CDev.hpp>

MS5611::MS5611(device::Device *interface, ms5611::prom_u &prom_buf, const char *path,
           enum MS56XX_DEVICE_TYPES device_type) :
    CDev(path),
    ScheduledWorkItem(MODULE_NAME, px4::device_bus_to_wq(interface->get_device_id())),
    _interface(interface),
    _prom(prom_buf.s),
    _reports(nullptr),
    _device_type(device_type),
    _collect_phase(false),
    _measure_phase(0),
    _TEMP(0),
    _OFF(0),
    _SENS(0),
    _baro_topic(nullptr),
    _orb_class_instance(-1),
    _class_instance(-1),
    _sample_perf(perf_alloc(PC_ELAPSED, "ms5611_read")),
    _measure_perf(perf_alloc(PC_ELAPSED, "ms5611_measure")),
    _comms_errors(perf_alloc(PC_COUNT, "ms5611_com_err"))
{
}

MS5611::~MS5611()
{
    /* make sure we are truly inactive */
    stop();

    if (_class_instance != -1) {
        unregister_class_devname(get_devname(), _class_instance);
    }

    /* free any existing reports */
    if (_reports != nullptr) {
        delete _reports;
    }

    // free perf counters
    perf_free(_sample_perf);
    perf_free(_measure_perf);
    perf_free(_comms_errors);

    delete _interface;
}

int
MS5611::init()
{
    int ret;
    bool autodetect = false;

    ret = CDev::init();

    if (ret != OK) {
        PX4_DEBUG("CDev init failed");
        goto out;
    }

    /* allocate basic report buffers */
    _reports = new ringbuffer::RingBuffer(2, sizeof(sensor_baro_s));

    if (_reports == nullptr) {
        PX4_DEBUG("can't get memory for reports");
        ret = -ENOMEM;
        goto out;
    }

    /* register alternate interfaces if we have to */
    _class_instance = register_class_devname(BARO_BASE_DEVICE_PATH);

    sensor_baro_s brp;
    /* do a first measurement cycle to populate reports with valid data */
    _measure_phase = 0;
    _reports->flush();

    if (_device_type == MS56XX_DEVICE) {
        autodetect = true;
        /* try first with MS5611 and fallback to MS5607 */
        _device_type = MS5611_DEVICE;
    }

    while (true) {
        /* do temperature first */
        if (OK != measure()) {
            ret = -EIO;
            break;
        }

        px4_usleep(MS5611_CONVERSION_INTERVAL);

        if (OK != collect()) {
            ret = -EIO;
            break;
        }

        /* now do a pressure measurement */
        if (OK != measure()) {
            ret = -EIO;
            break;
        }

        px4_usleep(MS5611_CONVERSION_INTERVAL);

        if (OK != collect()) {
            ret = -EIO;
            break;
        }

        /* state machine will have generated a report, copy it out */
        _reports->get(&brp);

        if (autodetect) {
            if (_device_type == MS5611_DEVICE) {
                if (brp.pressure < 520.0f) {
                    /* This is likely not this device, try again */
                    _device_type = MS5607_DEVICE;
                    _measure_phase = 0;

                    continue;
                }

            } else if (_device_type == MS5607_DEVICE) {
                if (brp.pressure < 520.0f) {
                    /* Both devices returned a very low pressure;
                     * have fun on Everest using MS5611 */
                    _device_type = MS5611_DEVICE;
                }
            }
        }

        switch (_device_type) {
        default:

        /* fall through */
        case MS5611_DEVICE:
            _interface->set_device_type(DRV_BARO_DEVTYPE_MS5611);
            break;

        case MS5607_DEVICE:
            _interface->set_device_type(DRV_BARO_DEVTYPE_MS5607);
            break;
        }

        /* ensure correct devid */
        brp.device_id = _interface->get_device_id();

        ret = OK;

        _baro_topic = orb_advertise_multi(ORB_ID(sensor_baro), &brp,
                          &_orb_class_instance, _interface->external() ? ORB_PRIO_HIGH : ORB_PRIO_DEFAULT);

        if (_baro_topic == nullptr) {
            warnx("failed to create sensor_baro publication");
        }

        break;
    }

out:
    return ret;
}

ssize_t
MS5611::read(cdev::file_t *filp, char *buffer, size_t buflen)
{
    unsigned count = buflen / sizeof(sensor_baro_s);
    sensor_baro_s *brp = reinterpret_cast<sensor_baro_s *>(buffer);
    int ret = 0;

    /* buffer must be large enough */
    if (count < 1) {
        return -ENOSPC;
    }

    /* if automatic measurement is enabled */
    if (_measure_interval > 0) {

        /*
         * While there is space in the caller's buffer, and reports, copy them.
         * Note that we may be pre-empted by the workq thread while we are doing this;
         * we are careful to avoid racing with them.
         */
        while (count--) {
            if (_reports->get(brp)) {
                ret += sizeof(*brp);
                brp++;
            }
        }

        /* if there was no data, warn the caller */
        return ret ? ret : -EAGAIN;
    }

    /* manual measurement - run one conversion */
    do {
        _measure_phase = 0;
        _reports->flush();

        /* do temperature first */
        if (OK != measure()) {
            ret = -EIO;
            break;
        }

        px4_usleep(MS5611_CONVERSION_INTERVAL);

        if (OK != collect()) {
            ret = -EIO;
            break;
        }

        /* now do a pressure measurement */
        if (OK != measure()) {
            ret = -EIO;
            break;
        }

        px4_usleep(MS5611_CONVERSION_INTERVAL);

        if (OK != collect()) {
            ret = -EIO;
            break;
        }

        /* state machine will have generated a report, copy it out */
        if (_reports->get(brp)) {
            ret = sizeof(*brp);
        }

    } while (0);

    return ret;
}

int
MS5611::ioctl(cdev::file_t *filp, int cmd, unsigned long arg)
{
    switch (cmd) {

    case SENSORIOCSPOLLRATE: {
            switch (arg) {

            /* zero would be bad */
            case 0:
                return -EINVAL;

            /* set default polling rate */
            case SENSOR_POLLRATE_DEFAULT: {
                    /* do we need to start internal polling? */
                    bool want_start = (_measure_interval == 0);

                    /* set interval for next measurement to minimum legal value */
                    _measure_interval = MS5611_CONVERSION_INTERVAL;

                    /* if we need to start the poll state machine, do it */
                    if (want_start) {
                        start();
                    }

                    return OK;
                }

            /* adjust to a legal polling interval in Hz */
            default: {
                    /* do we need to start internal polling? */
                    bool want_start = (_measure_interval == 0);

                    /* convert hz to interval via microseconds */
                    unsigned interval = (1000000 / arg);

                    /* check against maximum rate */
                    if (_measure_interval < MS5611_CONVERSION_INTERVAL) {
                        return -EINVAL;
                    }

                    /* update interval for next measurement */
                    _measure_interval = interval;

                    /* if we need to start the poll state machine, do it */
                    if (want_start) {
                        start();
                    }

                    return OK;
                }
            }
        }

    case SENSORIOCRESET:
        /*
         * Since we are initialized, we do not need to do anything, since the
         * PROM is correctly read and the part does not need to be configured.
         */
        return OK;

    default:
        break;
    }

    /* give it to the bus-specific superclass */
    // return bus_ioctl(filp, cmd, arg);
    return CDev::ioctl(filp, cmd, arg);
}

void
MS5611::start()
{
    /* reset the report ring and state machine */
    _collect_phase = false;
    _measure_phase = 0;
    _reports->flush();

    /* schedule a cycle to start things */
    ScheduleNow();
}

void
MS5611::stop()
{
    ScheduleClear();
}

void
MS5611::Run()
{
    int ret;
    unsigned dummy;

    /* collection phase? */
    if (_collect_phase) {

        /* perform collection */
        ret = collect();

        if (ret != OK) {
            if (ret == -6) {
                /*
                 * The ms5611 seems to regularly fail to respond to
                 * its address; this happens often enough that we'd rather not
                 * spam the console with a message for this.
                 */
            } else {
                //DEVICE_LOG("collection error %d", ret);
            }

            /* issue a reset command to the sensor */
            _interface->ioctl(IOCTL_RESET, dummy);
            /* reset the collection state machine and try again - we need
             * to wait 2.8 ms after issuing the sensor reset command
             * according to the MS5611 datasheet
             */
            ScheduleDelayed(2800);
            return;
        }

        /* next phase is measurement */
        _collect_phase = false;

        /*
         * Is there a collect->measure gap?
         * Don't inject one after temperature measurements, so we can keep
         * doing pressure measurements at something close to the desired rate.
         */
        if ((_measure_phase != 0) &&
            (_measure_interval > MS5611_CONVERSION_INTERVAL)) {

            /* schedule a fresh cycle call when we are ready to measure again */
            ScheduleDelayed(_measure_interval - MS5611_CONVERSION_INTERVAL);

            return;
        }
    }

    /* measurement phase */
    ret = measure();

    if (ret != OK) {
        /* issue a reset command to the sensor */
        _interface->ioctl(IOCTL_RESET, dummy);
        /* reset the collection state machine and try again */
        start();
        return;
    }

    /* next phase is collection */
    _collect_phase = true;

    /* schedule a fresh cycle call when the measurement is done */
    ScheduleDelayed(MS5611_CONVERSION_INTERVAL);
}

int
MS5611::measure()
{
    int ret;

    perf_begin(_measure_perf);

    /*
     * In phase zero, request temperature; in other phases, request pressure.
     */
    unsigned addr = (_measure_phase == 0) ? ADDR_CMD_CONVERT_D2 : ADDR_CMD_CONVERT_D1;

    /*
     * Send the command to begin measuring.
     */
    ret = _interface->ioctl(IOCTL_MEASURE, addr);

    if (OK != ret) {
        perf_count(_comms_errors);
    }

    perf_end(_measure_perf);

    return ret;
}

int
MS5611::collect()
{
    int ret;
    uint32_t raw;

    perf_begin(_sample_perf);

    sensor_baro_s report;
    /* this should be fairly close to the end of the conversion, so the best approximation of the time */
    report.timestamp = hrt_absolute_time();
    report.error_count = perf_event_count(_comms_errors);

    /* read the most recent measurement - read offset/size are hardcoded in the interface */
    ret = _interface->read(0, (void *)&raw, 0);

    if (ret < 0) {
        perf_count(_comms_errors);
        perf_end(_sample_perf);
        return ret;
    }

    /* handle a measurement */
    if (_measure_phase == 0) {

        /* temperature offset (in ADC units) */
        int32_t dT = (int32_t)raw - ((int32_t)_prom.c5_reference_temp << 8);

        /* absolute temperature in centidegrees - note intermediate value is outside 32-bit range */
        _TEMP = 2000 + (int32_t)(((int64_t)dT * _prom.c6_temp_coeff_temp) >> 23);

        /* base sensor scale/offset values */
        if (_device_type == MS5611_DEVICE) {

            /* Perform MS5611 Caculation */

            _OFF  = ((int64_t)_prom.c2_pressure_offset << 16) + (((int64_t)_prom.c4_temp_coeff_pres_offset * dT) >> 7);
            _SENS = ((int64_t)_prom.c1_pressure_sens << 15) + (((int64_t)_prom.c3_temp_coeff_pres_sens * dT) >> 8);

            /* MS5611 temperature compensation */

            if (_TEMP < 2000) {

                int32_t T2 = POW2(dT) >> 31;

                int64_t f = POW2((int64_t)_TEMP - 2000);
                int64_t OFF2 = 5 * f >> 1;
                int64_t SENS2 = 5 * f >> 2;

                if (_TEMP < -1500) {

                    int64_t f2 = POW2(_TEMP + 1500);
                    OFF2 += 7 * f2;
                    SENS2 += 11 * f2 >> 1;
                }

                _TEMP -= T2;
                _OFF  -= OFF2;
                _SENS -= SENS2;
            }

        } else if (_device_type == MS5607_DEVICE) {

            /* Perform MS5607 Caculation */

            _OFF  = ((int64_t)_prom.c2_pressure_offset << 17) + (((int64_t)_prom.c4_temp_coeff_pres_offset * dT) >> 6);
            _SENS = ((int64_t)_prom.c1_pressure_sens << 16) + (((int64_t)_prom.c3_temp_coeff_pres_sens * dT) >> 7);

            /* MS5607 temperature compensation */

            if (_TEMP < 2000) {

                int32_t T2 = POW2(dT) >> 31;

                int64_t f = POW2((int64_t)_TEMP - 2000);
                int64_t OFF2 = 61 * f >> 4;
                int64_t SENS2 = 2 * f;

                if (_TEMP < -1500) {
                    int64_t f2 = POW2(_TEMP + 1500);
                    OFF2 += 15 * f2;
                    SENS2 += 8 * f2;
                }

                _TEMP -= T2;
                _OFF  -= OFF2;
                _SENS -= SENS2;
            }
        }

    } else {

        /* pressure calculation, result in Pa */
        int32_t P = (((raw * _SENS) >> 21) - _OFF) >> 15;
        _P = P * 0.01f;
        _T = _TEMP * 0.01f;

        /* generate a new report */
        report.temperature = _TEMP / 100.0f;
        report.pressure = P / 100.0f;       /* convert to millibar */

        /* return device ID */
        report.device_id = _interface->get_device_id();

        /* publish it */
        if (_baro_topic != nullptr) {
            /* publish it */
            orb_publish(ORB_ID(sensor_baro), _baro_topic, &report);
        }

        _reports->force(&report);

        /* notify anyone waiting for data */
        poll_notify(POLLIN);
    }

    /* update the measurement state machine */
    INCREMENT(_measure_phase, MS5611_MEASUREMENT_RATIO + 1);

    perf_end(_sample_perf);

    return OK;
}

void
MS5611::print_info()
{
    perf_print_counter(_sample_perf);
    perf_print_counter(_comms_errors);
    printf("poll interval:  %u\n", _measure_interval);
    _reports->print_info("report queue");
    printf("device:         %s\n", _device_type == MS5611_DEVICE ? "ms5611" : "ms5607");

    sensor_baro_s brp = {};
    _reports->get(&brp);
    print_message(brp);
}

/**
 * Local functions in support of the shell command.
 */
namespace ms5611
{

/**
 * MS5611 crc4 cribbed from the datasheet
 */
bool
crc4(uint16_t *n_prom)
{
    int16_t cnt;
    uint16_t n_rem;
    uint16_t crc_read;
    uint8_t n_bit;

    n_rem = 0x00;

    /* save the read crc */
    crc_read = n_prom[7];

    /* remove CRC byte */
    n_prom[7] = (0xFF00 & (n_prom[7]));

    for (cnt = 0; cnt < 16; cnt++) {
        /* uneven bytes */
        if (cnt & 1) {
            n_rem ^= (uint8_t)((n_prom[cnt >> 1]) & 0x00FF);

        } else {
            n_rem ^= (uint8_t)(n_prom[cnt >> 1] >> 8);
        }

        for (n_bit = 8; n_bit > 0; n_bit--) {
            if (n_rem & 0x8000) {
                n_rem = (n_rem << 1) ^ 0x3000;

            } else {
                n_rem = (n_rem << 1);
            }
        }
    }

    /* final 4 bit remainder is CRC value */
    n_rem = (0x000F & (n_rem >> 12));
    n_prom[7] = crc_read;

    /* return true if CRCs match */
    return (0x000F & crc_read) == (n_rem ^ 0x00);
}

} // namespace ms5611