srf02.cpp

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/**
 * @file srf02.cpp
 *
 * Driver for the SRF02 sonar range finder adapted from the Maxbotix sonar range finder driver (srf02).
 */

#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/defines.h>
#include <px4_platform_common/getopt.h>
#include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
#include <containers/Array.hpp>

#include <drivers/device/i2c.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <semaphore.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <stdio.h>
#include <math.h>
#include <unistd.h>

#include <perf/perf_counter.h>

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

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

#include <board_config.h>

/* Configuration Constants */
#define SRF02_BASEADDR              0x70    // 7-bit address. 8-bit address is 0xE0.
#define SRF02_BUS_DEFAULT           PX4_I2C_BUS_EXPANSION
#define SRF02_DEVICE_PATH           "/dev/srf02"

/* SRF02 Registers addresses */
#define SRF02_TAKE_RANGE_REG            0x51    // Measure range Register.
#define SRF02_SET_ADDRESS_0         0xA0    // Change address 0 Register.
#define SRF02_SET_ADDRESS_1         0xAA    // Change address 1 Register.
#define SRF02_SET_ADDRESS_2         0xA5    // Change address 2 Register.

/* Device limits */
#define SRF02_MIN_DISTANCE          (0.20f)
#define SRF02_MAX_DISTANCE          (7.65f)

#define SRF02_CONVERSION_INTERVAL       100000  // 60ms for one sonar.
#define SRF02_INTERVAL_BETWEEN_SUCCESIVE_FIRES  100000  // 30ms between each sonar measurement (watch out for interference!).

class SRF02 : public device::I2C, public px4::ScheduledWorkItem
{
public:
    SRF02(uint8_t rotation = distance_sensor_s::ROTATION_DOWNWARD_FACING, int bus = SRF02_BUS_DEFAULT,
          int address = SRF02_BASEADDR);
    virtual ~SRF02();

    int init() override;

    int ioctl(device::file_t *filp, int cmd, unsigned long arg) override;

    /**
     * Diagnostics - print some basic information about the driver.
     */
    void print_info();

    ssize_t read(device::file_t *filp, char *buffer, size_t buflen) override;

protected:
    int probe() override;

private:

    int collect();

    int measure();

    /**
     * Test whether the device supported by the driver is present at a
     * specific address.
     * @param address The I2C bus address to probe.
     * @return True if the device is present.
     */
    int probe_address(uint8_t address);

    /**
     * Perform a poll cycle; collect from the previous measurement
     * and start a new one.
     */
    void Run() override;

    /**
     * Initialise the automatic measurement state machine and start it.
     *
     * @note This function is called at open and error time.  It might make sense
     *       to make it more aggressive about resetting the bus in case of errors.
     */
    void start();

    /**
     * Stop the automatic measurement state machine.
     */
    void stop();

    px4::Array<uint8_t, RANGE_FINDER_MAX_SENSORS>   addr_ind;   // Temp sonar i2c address vector.

    bool _sensor_ok{false};
    bool _collect_phase{false};

    int _class_instance{-1};
    int _cycling_rate{0};           // Initialize cycling rate to zero, (can differ depending on one sonar or multiple).
    int _measure_interval{0};
    int _orb_class_instance{-1};

    uint8_t _cycle_counter{0};      // Initialize counter to zero - used to change i2c adresses for multiple devices.
    uint8_t _index_counter{0};      // Initialize temp sonar i2c address to zero.
    uint8_t _rotation;

    float _max_distance{SRF02_MAX_DISTANCE};
    float _min_distance{SRF02_MIN_DISTANCE};

    perf_counter_t _comms_errors{perf_alloc(PC_COUNT, "srf02_com_err")};
    perf_counter_t _sample_perf{perf_alloc(PC_ELAPSED, "srf02_read")};

    orb_advert_t _distance_sensor_topic{nullptr};

    ringbuffer::RingBuffer *_reports{nullptr};
};

/*
 * Driver 'main' command.
 */
extern "C" __EXPORT int srf02_main(int argc, char *argv[]);

SRF02::SRF02(uint8_t rotation, int bus, int address) :
    I2C("SRF02", SRF02_DEVICE_PATH, bus, address, 100000),
    ScheduledWorkItem(MODULE_NAME, px4::device_bus_to_wq(get_device_id())),
    _rotation(rotation)
{
}

SRF02::~SRF02()
{
    // Ensure we are truly inactive.
    stop();

    // Free any existing reports.
    if (_reports != nullptr) {
        delete _reports;
    }

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

    // Free perf counters.
    perf_free(_sample_perf);
    perf_free(_comms_errors);
}

int
SRF02::collect()
{
    // Read from the sensor.
    uint8_t val[2] = {0, 0};
    uint8_t cmd = 0x02;
    perf_begin(_sample_perf);

    int ret = transfer(&cmd, 1, nullptr, 0);
    ret = transfer(nullptr, 0, &val[0], 2);

    if (ret < 0) {
        PX4_DEBUG("error reading from sensor: %d", ret);
        perf_count(_comms_errors);
        perf_end(_sample_perf);
        return ret;
    }

    uint16_t distance_cm = val[0] << 8 | val[1];
    float distance_m = float(distance_cm) * 1e-2f;

    struct distance_sensor_s report;
    report.current_distance = distance_m;
    report.id       = 0;    // TODO: set proper ID.
    report.max_distance     = _max_distance;
    report.min_distance     = _min_distance;
    report.orientation  = _rotation;
    report.signal_quality   = -1;
    report.variance     = 0.0f;
    report.timestamp    = hrt_absolute_time();
    report.type         = distance_sensor_s::MAV_DISTANCE_SENSOR_ULTRASOUND;

    // Publish it, if we are the primary.
    if (_distance_sensor_topic != nullptr) {
        orb_publish(ORB_ID(distance_sensor), _distance_sensor_topic, &report);
    }

    _reports->force(&report);

    // Notify anyone waiting for data.
    poll_notify(POLLIN);
    perf_end(_sample_perf);
    return PX4_OK;
}

int
SRF02::init()
{
    // I2C init (and probe) first.
    if (I2C::init() != OK) {
        return PX4_ERROR;
    }

    // Allocate basic report buffers.
    _reports = new ringbuffer::RingBuffer(2, sizeof(distance_sensor_s));

    _index_counter = SRF02_BASEADDR;        // Set temp sonar i2c address to base adress.
    set_device_address(_index_counter);     // Set I2c port to temp sonar i2c adress.

    if (_reports == nullptr) {
        return PX4_ERROR;
    }

    _class_instance = register_class_devname(RANGE_FINDER_BASE_DEVICE_PATH);

    // Get a publish handle on the range finder topic.
    struct distance_sensor_s ds_report = {};

    _distance_sensor_topic = orb_advertise_multi(ORB_ID(distance_sensor), &ds_report,
                 &_orb_class_instance, ORB_PRIO_LOW);

    if (_distance_sensor_topic == nullptr) {
        PX4_ERR("failed to create distance_sensor object");
    }

    // XXX we should find out why we need to wait 200 ms here
    px4_usleep(200000);

    /* Check for connected rangefinders on each i2c port:
     *   We start from i2c base address (0x70 = 112) and count downwards,
     *   so the second iteration it uses i2c address 111, third iteration 110, and so on. */
    for (unsigned counter = 0; counter <= RANGE_FINDER_MAX_SENSORS; counter++) {
        _index_counter = SRF02_BASEADDR - counter;      // Set temp sonar i2c address to base adress - counter.
        set_device_address(_index_counter);             // Set I2c port to temp sonar i2c adress.

        int ret = measure();

        if (ret == 0) {
            // Sonar is present -> store address_index in array.
            addr_ind.push_back(_index_counter);
            PX4_DEBUG("sonar added");
        }
    }

    _index_counter = SRF02_BASEADDR;
    set_device_address(_index_counter); // Set i2c port back to base adress for rest of driver.

    // If only one sonar detected, no special timing is required between firing, so use default.
    if (addr_ind.size() == 1) {
        _cycling_rate = SRF02_CONVERSION_INTERVAL;

    } else {
        _cycling_rate = SRF02_INTERVAL_BETWEEN_SUCCESIVE_FIRES;
    }

    // Show the connected sonars in terminal.
    for (unsigned i = 0; i < addr_ind.size(); i++) {
        PX4_DEBUG("sonar %d with address %d added", (i + 1), addr_ind[i]);
    }

    PX4_DEBUG("Number of sonars connected: %zu", addr_ind.size());

    // Sensor is ok, but we don't really know if it is within range.
    _sensor_ok = true;

    return PX4_OK;
}

int
SRF02::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 = _cycling_rate;

                    // 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.
                    int interval = (1000000 / arg);

                    // check against maximum rate.
                    if (interval < _cycling_rate) {
                        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;
                }
            }
        }

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

int
SRF02::measure()
{
    uint8_t cmd[2];
    cmd[0] = 0x00;
    cmd[1] = SRF02_TAKE_RANGE_REG;

    // Send the command to begin a measurement.
    int ret = transfer(cmd, 2, nullptr, 0);

    if (ret != PX4_OK) {
        perf_count(_comms_errors);
        PX4_DEBUG("i2c::transfer returned %d", ret);
        return ret;
    }

    return PX4_OK;
}

void
SRF02::print_info()
{
    perf_print_counter(_sample_perf);
    perf_print_counter(_comms_errors);
    printf("poll interval:  %u\n", _measure_interval);
    _reports->print_info("report queue");
}

int
SRF02::probe()
{
    return measure();
}

ssize_t
SRF02::read(device::file_t *filp, char *buffer, size_t buflen)
{

    unsigned count = buflen / sizeof(struct distance_sensor_s);
    struct distance_sensor_s *rbuf = reinterpret_cast<struct distance_sensor_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(rbuf)) {
                ret += sizeof(*rbuf);
                rbuf++;
            }
        }

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

    // Manual measurement - run one conversion.
    do {
        _reports->flush();

        // Trigger a measurement.
        if (OK != measure()) {
            ret = -EIO;
            break;
        }

        // Wait for it to complete.
        px4_usleep(_cycling_rate * 2);

        // Run the collection phase.
        if (OK != collect()) {
            ret = -EIO;
            break;
        }

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

    } while (0);

    return ret;
}

void
SRF02::Run()
{
    if (_collect_phase) {
        _index_counter = addr_ind[_cycle_counter]; // Sonar from previous iteration collect is now read out.
        set_device_address(_index_counter);

        // Perform collection.
        if (OK != collect()) {
            PX4_DEBUG("collection error");
            // If error restart the measurement state machine.
            start();
            return;
        }

        // Next phase is measurement.
        _collect_phase = false;

        // Change i2c adress to next sonar.
        _cycle_counter = _cycle_counter + 1;

        if (_cycle_counter >= addr_ind.size()) {
            _cycle_counter = 0;
        }

        // Is there a collect->measure gap? Yes, and the timing is set equal to the cycling_rate
        // Otherwise the next sonar would fire without the first one having received its reflected sonar pulse.
        if (_measure_interval > _cycling_rate) {

            // schedule a fresh cycle call when we are ready to measure again.
            ScheduleDelayed(_measure_interval - _cycling_rate);
            return;
        }
    }

    // Measurement (firing) phase - Ensure sonar i2c adress is still correct.
    _index_counter = addr_ind[_cycle_counter];
    set_device_address(_index_counter);

    // Perform measurement.
    if (OK != measure()) {
        PX4_DEBUG("measure error sonar adress %d", _index_counter);
    }

    // Next phase is collection.
    _collect_phase = true;

    // Schedule a fresh cycle call when the measurement is done.
    ScheduleDelayed(_cycling_rate);
}

void
SRF02::start()
{
    // Reset the report ring and state machine.
    _collect_phase = false;
    _reports->flush();

    // Schedule a cycle to start things.
    ScheduleDelayed(5);
}

void
SRF02::stop()
{
    ScheduleClear();
}


/**
 * Local functions in support of the shell command.
 */
namespace srf02
{

SRF02   *g_dev;

int     reset();
int     start(uint8_t rotation);
int     start_bus(uint8_t rotation, int i2c_bus);
int     status();
int     stop();
int     test();
int     usage();

/**
 * Reset the driver.
 */
int
reset()
{
    int fd = px4_open(SRF02_DEVICE_PATH, O_RDONLY);

    if (fd < 0) {
        PX4_ERR("failed");
        return PX4_ERROR;
    }

    if (ioctl(fd, SENSORIOCRESET, 0) < 0) {
        PX4_ERR("driver reset failed");
        return PX4_ERROR;
    }

    if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0) {
        PX4_ERR("driver poll restart failed");
        return PX4_ERROR;
    }

    px4_close(fd);
    return PX4_OK;
}

/**
 * Attempt to start driver on all available I2C busses.
 *
 * This function will return as soon as the first sensor
 * is detected on one of the available busses or if no
 * sensors are detected.
 */
int
start(uint8_t rotation)
{
    if (g_dev != nullptr) {
        PX4_ERR("already started");
        return PX4_ERROR;
    }

    for (unsigned i = 0; i < NUM_I2C_BUS_OPTIONS; i++) {
        if (start_bus(rotation, i2c_bus_options[i]) == PX4_OK) {
            return PX4_OK;
        }
    }

    return PX4_ERROR;
}

/**
 * Start the driver on a specific bus.
 *
 * This function only returns if the sensor is up and running
 * or could not be detected successfully.
 */
int
start_bus(uint8_t rotation, int i2c_bus)
{
    if (g_dev != nullptr) {
        PX4_ERR("already started");
        return PX4_ERROR;
    }

    // Create the driver.
    g_dev = new SRF02(rotation, i2c_bus);

    if (g_dev == nullptr) {
        PX4_ERR("failed to instantiate the device");
        return PX4_ERROR;
    }

    if (OK != g_dev->init()) {
        PX4_ERR("failed to initialize the device");
        delete g_dev;
        g_dev = nullptr;
        return PX4_ERROR;
    }

    // Set the poll rate to default, starts automatic data collection.
    int fd = px4_open(SRF02_DEVICE_PATH, O_RDONLY);

    if (fd < 0) {
        delete g_dev;
        g_dev = nullptr;
        return PX4_ERROR;
    }

    if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0) {
        delete g_dev;
        g_dev = nullptr;
        px4_close(fd);
        return PX4_ERROR;
    }

    px4_close(fd);
    return PX4_OK;
}

/**
 * Print the driver status.
 */
int
status()
{
    if (g_dev == nullptr) {
        PX4_ERR("driver not running");
        return PX4_ERROR;
    }

    printf("state @ %p\n", g_dev);
    g_dev->print_info();

    return PX4_OK;
}

/**
 * Stop the driver
 */
int
stop()
{
    if (g_dev != nullptr) {
        delete g_dev;
        g_dev = nullptr;

    } else {
        PX4_ERR("driver not running");
        return PX4_ERROR;
    }

    return PX4_OK;
}

/**
 * Perform some basic functional tests on the driver;
 * make sure we can collect data from the sensor in polled
 * and automatic modes.
 */
int
test()
{
    int fd = px4_open(SRF02_DEVICE_PATH, O_RDONLY);

    if (fd < 0) {
        PX4_ERR("%s open failed (try 'srf02 start' if the driver is not running)", SRF02_DEVICE_PATH);
        return PX4_ERROR;
    }

    struct distance_sensor_s report;

    // Perform a simple demand read.
    ssize_t sz = read(fd, &report, sizeof(report));

    if (sz != sizeof(report)) {
        PX4_ERR("immediate read failed");
        return PX4_ERROR;
    }

    print_message(report);

    // Start the sensor polling at 2Hz.
    if (OK != ioctl(fd, SENSORIOCSPOLLRATE, 2)) {
        PX4_ERR("failed to set 2Hz poll rate");
        return PX4_ERROR;
    }

    // Read the sensor 5x and report each value.
    for (unsigned i = 0; i < 5; i++) {
        struct pollfd fds;

        // Wait for data to be ready.
        fds.fd = fd;
        fds.events = POLLIN;
        int ret = poll(&fds, 1, 2000);

        if (ret != 1) {
            PX4_ERR("timed out waiting for sensor data");
            return PX4_ERROR;
        }

        // Now go get it.
        sz = read(fd, &report, sizeof(report));

        if (sz != sizeof(report)) {
            PX4_ERR("periodic read failed");
            return PX4_ERROR;
        }

        print_message(report);
    }

    // Reset the sensor polling to default rate.
    if (OK != ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT)) {
        PX4_ERR("failed to set default poll rate");
        return PX4_ERROR;
    }

    PX4_INFO("PASS");
    return PX4_OK;
}

int
usage()
{
    PX4_INFO("usage: srf02 command [options]");
    PX4_INFO("options:");
    PX4_INFO("\t-b --bus i2cbus (%d)", SRF02_BUS_DEFAULT);
    PX4_INFO("\t-a --all");
    PX4_INFO("\t-R --rotation (%d)", distance_sensor_s::ROTATION_DOWNWARD_FACING);
    PX4_INFO("command:");
    PX4_INFO("\tstart|stop|test|reset|info");
    return PX4_OK;
}

} // namespace srf02


/**
 * Driver 'main' command.
 */
extern "C" __EXPORT int srf02_main(int argc, char *argv[])
{
    const char *myoptarg = nullptr;

    int ch;
    int myoptind = 1;
    int i2c_bus = SRF02_BUS_DEFAULT;

    uint8_t rotation = distance_sensor_s::ROTATION_DOWNWARD_FACING;

    bool start_all = false;

    while ((ch = px4_getopt(argc, argv, "ab:R:", &myoptind, &myoptarg)) != EOF) {
        switch (ch) {
        case 'R':
            rotation = (uint8_t)atoi(myoptarg);
            break;

        case 'b':
            i2c_bus = atoi(myoptarg);
            break;

        case 'a':
            start_all = true;
            break;

        default:
            PX4_WARN("Unknown option!");
            return srf02::usage();
        }
    }

    if (myoptind >= argc) {
        return srf02::usage();
    }

    // Start/load the driver.
    if (!strcmp(argv[myoptind], "start")) {
        if (start_all) {
            return srf02::start(rotation);

        } else {
            return srf02::start_bus(rotation, i2c_bus);
        }
    }

    // Stop the driver.
    if (!strcmp(argv[myoptind], "stop")) {
        return srf02::stop();
    }

    // Test the driver/device.
    if (!strcmp(argv[myoptind], "test")) {
        return srf02::test();
    }

    // Reset the driver.
    if (!strcmp(argv[myoptind], "reset")) {
        return srf02::reset();
    }

    // Print driver information.
    if (!strcmp(argv[myoptind], "info") ||
        !strcmp(argv[myoptind], "status")) {
        return srf02::status();
    }

    return srf02::usage();
}