ulanding.cpp

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/**
 * @file ulanding.cpp
 * @author Jessica Stockham <jessica@aerotenna.com>
 * @author Roman Bapst <roman@uaventure.com>
 *
 * Driver for the uLanding radar from Aerotenna
 */

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

#include <drivers/device/device.h>
#include <drivers/device/ringbuffer.h>
#include <drivers/drv_hrt.h>
#include <drivers/drv_range_finder.h>
#include <mathlib/mathlib.h>
#include <perf/perf_counter.h>
#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/defines.h>
#include <px4_platform_common/getopt.h>
#include <px4_platform_common/workqueue.h>
#include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
#include <systemlib/err.h>
#include <uORB/topics/distance_sensor.h>
#include <uORB/uORB.h>


using namespace time_literals;

#define ULANDING_MEASURE_INTERVAL       10_ms
#define ULANDING_MAX_DISTANCE           50.0f
#define ULANDING_MIN_DISTANCE           0.315f
#define ULANDING_VERSION            1

#if defined(__PX4_POSIX_OCPOC)
#define RADAR_DEFAULT_PORT      "/dev/ttyS6"    // Default uLanding port on OCPOC.
#else
#define RADAR_DEFAULT_PORT      "/dev/ttyS2"    // Default serial port on Pixhawk (TELEM2), baudrate 115200
#endif

#if ULANDING_VERSION == 1
#define ULANDING_PACKET_HDR     254
#define ULANDING_BUFFER_LENGTH  18
#else
#define ULANDING_PACKET_HDR     72
#define ULANDING_BUFFER_LENGTH  9
#endif

/**
 * Assume standard deviation to be equal to sensor resolution.
 * Static bench tests have shown that the sensor ouput does
 * not vary if the unit is not moved.
 */
#define SENS_VARIANCE           0.045f * 0.045f


class Radar : public cdev::CDev, public px4::ScheduledWorkItem
{
public:
    /**
     * Default Constructor
     * @param port The serial port to open for communicating with the sensor.
     * @param rotation The sensor rotation relative to the vehicle body.
     */
    Radar(const char *port = RADAR_DEFAULT_PORT, uint8_t rotation = distance_sensor_s::ROTATION_DOWNWARD_FACING);

    /** Virtual destructor */
    virtual ~Radar();

    /**
     * Method : init()
     * This method initializes the general driver for a range finder sensor.
     */
    virtual int init() override;

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

private:

    /**
     * Reads data from serial UART and places it into a buffer.
     */
    int collect();

    /**
     * Opens and configures the UART serial communications port.
     * @param speed The baudrate (speed) to configure the serial UART port.
     */
    int open_serial_port(const speed_t speed = B115200);

    /**
     * Perform a reading 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();

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

    char _port[20];

    int _file_descriptor{-1};
    int _orb_class_instance{-1};

    unsigned int _head{0};
    unsigned int _tail{0};

    uint8_t _buffer[ULANDING_BUFFER_LENGTH] {};
    uint8_t _rotation;

    perf_counter_t _comms_errors{perf_alloc(PC_COUNT, "radar_com_err")};
    perf_counter_t _sample_perf{perf_alloc(PC_ELAPSED, "radar_read")};

    orb_advert_t _distance_sensor_topic{nullptr};
};

Radar::Radar(const char *port, uint8_t rotation) :
    CDev(RANGE_FINDER0_DEVICE_PATH),
    ScheduledWorkItem(MODULE_NAME, px4::serial_port_to_wq(port)),
    _rotation(rotation)
{
    /* store port name */
    strncpy(_port, port, sizeof(_port) - 1);
    /* enforce null termination */
    _port[sizeof(_port) - 1] = '\0';
}

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

    perf_free(_sample_perf);
    perf_free(_comms_errors);
}

int
Radar::collect()
{
    perf_begin(_sample_perf);

    int bytes_processed = 0;
    int distance_cm = -1;
    int index = 0;

    float distance_m = -1.0f;

    bool checksum_passed = false;

    // Read from the sensor UART buffer.
    int bytes_read = ::read(_file_descriptor, &_buffer[0], sizeof(_buffer));

    if (bytes_read > 0) {
        index = bytes_read - 6;

        while (index >= 0 && !checksum_passed) {
            if (_buffer[index] == ULANDING_PACKET_HDR) {
                bytes_processed = index;

                while (bytes_processed < bytes_read && !checksum_passed) {
                    if (ULANDING_VERSION == 1) {
                        uint8_t checksum_value = (_buffer[index + 1] + _buffer[index + 2] + _buffer[index + 3] + _buffer[index + 4]) & 0xFF;
                        uint8_t checksum_byte = _buffer[index + 5];

                        if (checksum_value == checksum_byte) {
                            checksum_passed = true;
                            distance_cm = (_buffer[index + 3] << 8) | _buffer[index + 2];
                            distance_m = static_cast<float>(distance_cm) / 100.f;
                        }

                    } else {
                        checksum_passed = true;
                        distance_cm = (_buffer[index + 1] & 0x7F);
                        distance_cm += ((_buffer[index + 2] & 0x7F) << 7);
                        distance_m = static_cast<float>(distance_cm) * 0.045f;
                        break;
                    }

                    bytes_processed++;
                }
            }

            index--;
        }
    }

    if (!checksum_passed) {
        return -EAGAIN;
    }

    distance_m = math::constrain(distance_m, ULANDING_MIN_DISTANCE, ULANDING_MAX_DISTANCE);

    distance_sensor_s report;
    report.current_distance = distance_m;
    report.id               = 0;    // TODO: set proper ID.
    report.max_distance     = ULANDING_MAX_DISTANCE;
    report.min_distance     = ULANDING_MIN_DISTANCE;
    report.orientation      = _rotation;
    report.signal_quality   = -1;
    report.timestamp        = hrt_absolute_time();
    report.type             = distance_sensor_s::MAV_DISTANCE_SENSOR_RADAR;
    report.variance         = SENS_VARIANCE;

    // Publish the new report.
    orb_publish(ORB_ID(distance_sensor), _distance_sensor_topic, &report);

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

    return PX4_OK;
}

int
Radar::init()
{
    // Intitialize the character device.
    if (CDev::init() != OK) {
        return PX4_ERROR;
    }

    // Get a publish handle on the range finder topic.
    distance_sensor_s ds_report = {};
    _distance_sensor_topic = orb_advertise_multi(ORB_ID(distance_sensor), &ds_report,
                 &_orb_class_instance, ORB_PRIO_HIGH);

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

    start();
    return PX4_OK;
}

int
Radar::open_serial_port(const speed_t speed)
{
    // File descriptor initialized?
    if (_file_descriptor > 0) {
        // PX4_INFO("serial port already open");
        return PX4_OK;
    }

    // Configure port flags for read/write, non-controlling, non-blocking.
    int flags = (O_RDWR | O_NOCTTY | O_NONBLOCK);

    // Open the serial port.
    _file_descriptor = ::open(_port, flags);

    if (_file_descriptor < 0) {
        PX4_ERR("open failed (%i)", errno);
        return PX4_ERROR;
    }

    if (!isatty(_file_descriptor)) {
        PX4_WARN("not a serial device");
        return PX4_ERROR;
    }

    termios uart_config = {};

    // Store the current port configuration. attributes.
    tcgetattr(_file_descriptor, &uart_config);

    uart_config.c_iflag &= ~(IGNBRK | BRKINT | ICRNL | INLCR | PARMRK | INPCK | ISTRIP | IXON);

    // Clear ONLCR flag (which appends a CR for every LF).
    uart_config.c_oflag &= ~ONLCR;

    // No parity, one stop bit.
    uart_config.c_cflag &= ~(CSTOPB | PARENB);

    // No line processing - echo off, echo newline off, canonical mode off, extended input processing off, signal chars off
    uart_config.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);

    // Set the input baud rate in the uart_config struct.
    int termios_state = cfsetispeed(&uart_config, speed);

    if (termios_state < 0) {
        PX4_ERR("CFG: %d ISPD", termios_state);
        ::close(_file_descriptor);
        return PX4_ERROR;
    }

    // Set the output baud rate in the uart_config struct.
    termios_state = cfsetospeed(&uart_config, speed);

    if (termios_state < 0) {
        PX4_ERR("CFG: %d OSPD", termios_state);
        ::close(_file_descriptor);
        return PX4_ERROR;
    }

    // Apply the modified port attributes.
    termios_state = tcsetattr(_file_descriptor, TCSANOW, &uart_config);

    if (termios_state < 0) {
        PX4_ERR("baud %d ATTR", termios_state);
        ::close(_file_descriptor);
        return PX4_ERROR;
    }

    PX4_INFO("successfully opened UART port %s", _port);
    return PX4_OK;
}

void
Radar::print_info()
{
    perf_print_counter(_sample_perf);
    perf_print_counter(_comms_errors);
    PX4_INFO("ulanding max distance %.2f m", static_cast<double>(ULANDING_MAX_DISTANCE));
    PX4_INFO("ulanding min distance %.2f m", static_cast<double>(ULANDING_MIN_DISTANCE));
    PX4_INFO("ulanding update rate: %.2f Hz", static_cast<double>(ULANDING_MEASURE_INTERVAL));
}

void
Radar::Run()
{
    // Ensure the serial port is open.
    open_serial_port();

    collect();
}

void
Radar::start()
{
    // Schedule the driver at regular intervals.
    ScheduleOnInterval(ULANDING_MEASURE_INTERVAL, 0);
    PX4_INFO("driver started");
}

void
Radar::stop()
{
    // Ensure the serial port is closed.
    ::close(_file_descriptor);

    // Clear the work queue schedule.
    ScheduleClear();
}

namespace radar
{
Radar   *g_dev;

int reset(const char *port = RADAR_DEFAULT_PORT);
int start(const char *port = RADAR_DEFAULT_PORT,
      const uint8_t rotation = distance_sensor_s::ROTATION_DOWNWARD_FACING);
int status();
int stop();
int test(const char *port = RADAR_DEFAULT_PORT);
int usage();

/**
 * Reset the driver.
 */
int
reset(const char *port)
{
    if (stop() == PX4_OK) {
        return start(port);
    }

    return PX4_ERROR;
}

/**
 * Start the driver.
 */
int
start(const char *port, const uint8_t rotation)
{
    if (g_dev != nullptr) {
        PX4_INFO("already started");
        return PX4_OK;
    }

    // Instantiate the driver.
    g_dev = new Radar(port, rotation);

    if (g_dev == nullptr) {
        PX4_ERR("object instantiate failed");
        return PX4_ERROR;
    }

    if (g_dev->init() != PX4_OK) {
        PX4_ERR("driver start failed");
        delete g_dev;
        g_dev = nullptr;
        return PX4_ERROR;
    }

    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;
    }

    return PX4_ERROR;
}

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

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

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

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

    print_message(report);
    return PX4_OK;
}

int
usage()
{
    PX4_INFO("usage: radar command [options]");
    PX4_INFO("command:");
    PX4_INFO("\treset|start|status|stop|test");
    PX4_INFO("options:");
    PX4_INFO("\t-R --rotation (%d)", distance_sensor_s::ROTATION_DOWNWARD_FACING);
    PX4_INFO("\t-d --device_path");
    return PX4_OK;
}

} // namespace radar


/**
 * Driver 'main' command.
 */
extern "C" __EXPORT int ulanding_radar_main(int argc, char *argv[])
{
    uint8_t rotation = distance_sensor_s::ROTATION_DOWNWARD_FACING;
    const char *device_path = RADAR_DEFAULT_PORT;
    int ch;
    int myoptind = 1;
    const char *myoptarg = nullptr;

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

        case 'd':
            device_path = myoptarg;
            break;

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

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

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

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

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

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

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

    return radar::usage();
}