airspeed.cpp

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/**
 * @file airspeed.cpp
 * @author Simon Wilks <simon@px4.io>
 * @author Lorenz Meier <lorenz@px4.io>
 *
 */

#include <px4_platform_common/px4_config.h>
#include <drivers/device/device.h>

#include <drivers/device/i2c.h>

#include <systemlib/err.h>
#include <parameters/param.h>
#include <perf/perf_counter.h>

#include <drivers/drv_airspeed.h>
#include <drivers/drv_hrt.h>
#include <drivers/device/ringbuffer.h>

#include <uORB/uORB.h>
#include <uORB/topics/differential_pressure.h>

#include <drivers/airspeed/airspeed.h>

Airspeed::Airspeed(int bus, int address, unsigned conversion_interval, const char *path) :
    I2C("Airspeed", path, bus, address, 100000),
    ScheduledWorkItem(MODULE_NAME, px4::device_bus_to_wq(get_device_id())),
    _sensor_ok(false),
    _measure_interval(0),
    _collect_phase(false),
    _diff_pres_offset(0.0f),
    _airspeed_pub(nullptr),
    _airspeed_orb_class_instance(-1),
    _class_instance(-1),
    _conversion_interval(conversion_interval),
    _sample_perf(perf_alloc(PC_ELAPSED, "aspd_read")),
    _comms_errors(perf_alloc(PC_COUNT, "aspd_com_err"))
{
}

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

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

    orb_unadvertise(_airspeed_pub);

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

int
Airspeed::init()
{
    /* do I2C init (and probe) first */
    if (I2C::init() != PX4_OK) {
        return PX4_ERROR;
    }

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

    /* advertise sensor topic, measure manually to initialize valid report */
    measure();
    differential_pressure_s arp = {};

    /* measurement will have generated a report, publish */
    _airspeed_pub = orb_advertise_multi(ORB_ID(differential_pressure), &arp, &_airspeed_orb_class_instance,
                        ORB_PRIO_HIGH - _class_instance);

    if (_airspeed_pub == nullptr) {
        PX4_WARN("uORB started?");
    }

    return PX4_OK;
}

int
Airspeed::probe()
{
    /* on initial power up the device may need more than one retry
       for detection. Once it is running the number of retries can
       be reduced
    */
    _retries = 4;
    int ret = measure();

    // drop back to 2 retries once initialised
    _retries = 2;
    return ret;
}

int
Airspeed::ioctl(device::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 = USEC2TICK(_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 tick interval via microseconds */
                    unsigned interval = (1000000 / arg);

                    /* check against maximum rate */
                    if (interval < _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;
                }
            }
        }
        break;

    case AIRSPEEDIOCSSCALE: {
            struct airspeed_scale *s = (struct airspeed_scale *)arg;
            _diff_pres_offset = s->offset_pa;
            return OK;
        }

    default:
        /* give it to the superclass */
        return I2C::ioctl(filp, cmd, arg);
    }
}

void
Airspeed::start()
{
    /* reset the report ring and state machine */
    _collect_phase = false;

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

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