PX4-Autopilot/src/drivers/ets_airspeed/ets_airspeed.cpp

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 * modification, are permitted provided that the following conditions
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/**
 * @file ets_airspeed.cpp
 * @author Simon Wilks
 *
 * Driver for the Eagle Tree Airspeed V3 connected via I2C.
 */

#include <nuttx/config.h>

#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 <errno.h>
#include <stdio.h>
#include <math.h>
#include <unistd.h>

#include <nuttx/arch.h>
#include <nuttx/wqueue.h>
#include <nuttx/clock.h>

#include <arch/board/board.h>

#include <systemlib/airspeed.h>
#include <systemlib/err.h>
#include <systemlib/param/param.h>
#include <systemlib/perf_counter.h>

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

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

/* Default I2C bus */
#define PX4_I2C_BUS_DEFAULT		PX4_I2C_BUS_EXPANSION

/* I2C bus address */
#define I2C_ADDRESS	0x75	/* 7-bit address. 8-bit address is 0xEA */

/* Register address */
#define READ_CMD	0x07	/* Read the data */

/**
 * The Eagle Tree Airspeed V3 cannot provide accurate reading below speeds of 15km/h.
 * You can set this value to 12 if you want a zero reading below 15km/h.
 */
#define MIN_ACCURATE_DIFF_PRES_PA 0

/* Measurement rate is 100Hz */
#define CONVERSION_INTERVAL	(1000000 / 100)	/* microseconds */

/* Oddly, ERROR is not defined for C++ */
#ifdef ERROR
# undef ERROR
#endif
static const int ERROR = -1;

#ifndef CONFIG_SCHED_WORKQUEUE
# error This requires CONFIG_SCHED_WORKQUEUE.
#endif

class ETSAirspeed : public device::I2C
{
public:
	ETSAirspeed(int bus, int address = I2C_ADDRESS);
	virtual ~ETSAirspeed();

	virtual int	init();

	virtual ssize_t	read(struct file *filp, char *buffer, size_t buflen);
	virtual int	ioctl(struct file *filp, int cmd, unsigned long arg);

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

protected:
	virtual int	probe();

private:
	work_s			_work;
	unsigned		_num_reports;
	volatile unsigned	_next_report;
	volatile unsigned	_oldest_report;
	differential_pressure_s	*_reports;
	bool			_sensor_ok;
	int			_measure_ticks;
	bool			_collect_phase;
	float			_diff_pres_offset;

	orb_advert_t		_airspeed_pub;

	perf_counter_t		_sample_perf;
	perf_counter_t		_comms_errors;
	perf_counter_t		_buffer_overflows;


	/**
	* 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);

	/**
	* 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();

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

	/**
	* Static trampoline from the workq context; because we don't have a
	* generic workq wrapper yet.
	*
	* @param arg		Instance pointer for the driver that is polling.
	*/
	static void	cycle_trampoline(void *arg);


};

/* helper macro for handling report buffer indices */
#define INCREMENT(_x, _lim)	do { _x++; if (_x >= _lim) _x = 0; } while(0)

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

ETSAirspeed::ETSAirspeed(int bus, int address) :
	I2C("ETSAirspeed", AIRSPEED_DEVICE_PATH, bus, address, 100000),
	_num_reports(0),
	_next_report(0),
	_oldest_report(0),
	_reports(nullptr),
	_sensor_ok(false),
	_measure_ticks(0),
	_collect_phase(false),
	_diff_pres_offset(0),
	_airspeed_pub(-1),
	_sample_perf(perf_alloc(PC_ELAPSED, "ets_airspeed_read")),
	_comms_errors(perf_alloc(PC_COUNT, "ets_airspeed_comms_errors")),
	_buffer_overflows(perf_alloc(PC_COUNT, "ets_airspeed_buffer_overflows"))
{
	// enable debug() calls
	_debug_enabled = true;

	// work_cancel in the dtor will explode if we don't do this...
	memset(&_work, 0, sizeof(_work));
}

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

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

int
ETSAirspeed::init()
{
	int ret = ERROR;

	/* do I2C init (and probe) first */
	if (I2C::init() != OK)
		goto out;

	/* allocate basic report buffers */
	_num_reports = 2;
	_reports = new struct differential_pressure_s[_num_reports];

	for (unsigned i = 0; i < _num_reports; i++)
		_reports[i].max_differential_pressure_pa = 0;

	if (_reports == nullptr)
		goto out;

	_oldest_report = _next_report = 0;

	/* get a publish handle on the airspeed topic */
	memset(&_reports[0], 0, sizeof(_reports[0]));
	_airspeed_pub = orb_advertise(ORB_ID(differential_pressure), &_reports[0]);

	if (_airspeed_pub < 0)
		debug("failed to create airspeed sensor object. Did you start uOrb?");

	ret = OK;
	/* sensor is ok, but we don't really know if it is within range */
	_sensor_ok = true;
out:
	return ret;
}

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

int
ETSAirspeed::ioctl(struct file *filp, int cmd, unsigned long arg)
{
	switch (cmd) {

	case SENSORIOCSPOLLRATE: {
			switch (arg) {

				/* switching to manual polling */
			case SENSOR_POLLRATE_MANUAL:
				stop();
				_measure_ticks = 0;
				return OK;

				/* external signalling (DRDY) not supported */
			case SENSOR_POLLRATE_EXTERNAL:

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

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

					/* set interval for next measurement to minimum legal value */
					_measure_ticks = 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_ticks == 0);

					/* convert hz to tick interval via microseconds */
					unsigned ticks = USEC2TICK(1000000 / arg);

					/* check against maximum rate */
					if (ticks < USEC2TICK(CONVERSION_INTERVAL))
						return -EINVAL;

					/* update interval for next measurement */
					_measure_ticks = ticks;

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

					return OK;
				}
			}
		}

	case SENSORIOCGPOLLRATE:
		if (_measure_ticks == 0)
			return SENSOR_POLLRATE_MANUAL;

		return (1000 / _measure_ticks);

	case SENSORIOCSQUEUEDEPTH: {
			/* add one to account for the sentinel in the ring */
			arg++;

			/* lower bound is mandatory, upper bound is a sanity check */
			if ((arg < 2) || (arg > 100))
				return -EINVAL;

			/* allocate new buffer */
			struct differential_pressure_s *buf = new struct differential_pressure_s[arg];

			if (nullptr == buf)
				return -ENOMEM;

			/* reset the measurement state machine with the new buffer, free the old */
			stop();
			delete[] _reports;
			_num_reports = arg;
			_reports = buf;
			start();

			return OK;
		}

	case SENSORIOCGQUEUEDEPTH:
		return _num_reports - 1;

	case SENSORIOCRESET:
		/* XXX implement this */
		return -EINVAL;

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

	case AIRSPEEDIOCGSCALE: {
		struct airspeed_scale *s = (struct airspeed_scale*)arg;
		s->offset_pa = _diff_pres_offset;
		s->scale = 1.0f;
		return OK;
		}

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

ssize_t
ETSAirspeed::read(struct file *filp, char *buffer, size_t buflen)
{
	unsigned count = buflen / sizeof(struct differential_pressure_s);
	int ret = 0;

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

	/* if automatic measurement is enabled */
	if (_measure_ticks > 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 (_oldest_report != _next_report) {
				memcpy(buffer, _reports + _oldest_report, sizeof(*_reports));
				ret += sizeof(_reports[0]);
				INCREMENT(_oldest_report, _num_reports);
			}
		}

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

	/* manual measurement - run one conversion */
	/* XXX really it'd be nice to lock against other readers here */
	do {
		_oldest_report = _next_report = 0;

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

		/* wait for it to complete */
		usleep(CONVERSION_INTERVAL);

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

		/* state machine will have generated a report, copy it out */
		memcpy(buffer, _reports, sizeof(*_reports));
		ret = sizeof(*_reports);

	} while (0);

	return ret;
}

int
ETSAirspeed::measure()
{
	int ret;

	/*
	 * Send the command to begin a measurement.
	 */
	uint8_t cmd = READ_CMD;
	ret = transfer(&cmd, 1, nullptr, 0);

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

	ret = OK;

	return ret;
}

int
ETSAirspeed::collect()
{
	int	ret = -EIO;

	/* read from the sensor */
	uint8_t val[2] = {0, 0};

	perf_begin(_sample_perf);

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

	if (ret < 0) {
		log("error reading from sensor: %d", ret);
		return ret;
	}

	uint16_t diff_pres_pa = val[1] << 8 | val[0];

	if (diff_pres_pa < _diff_pres_offset + MIN_ACCURATE_DIFF_PRES_PA) {
		diff_pres_pa = 0;

	} else {
		diff_pres_pa -= _diff_pres_offset;
	}

	// XXX we may want to smooth out the readings to remove noise.

	_reports[_next_report].timestamp = hrt_absolute_time();
	_reports[_next_report].differential_pressure_pa = diff_pres_pa;

	// Track maximum differential pressure measured (so we can work out top speed).
	if (diff_pres_pa > _reports[_next_report].max_differential_pressure_pa) {
		_reports[_next_report].max_differential_pressure_pa = diff_pres_pa;
	}

	/* announce the airspeed if needed, just publish else */
	orb_publish(ORB_ID(differential_pressure), _airspeed_pub, &_reports[_next_report]);

	/* post a report to the ring - note, not locked */
	INCREMENT(_next_report, _num_reports);

	/* if we are running up against the oldest report, toss it */
	if (_next_report == _oldest_report) {
		perf_count(_buffer_overflows);
		INCREMENT(_oldest_report, _num_reports);
	}

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

	ret = OK;

	perf_end(_sample_perf);

	return ret;
}

void
ETSAirspeed::start()
{
	/* reset the report ring and state machine */
	_collect_phase = false;
	_oldest_report = _next_report = 0;

	/* schedule a cycle to start things */
	work_queue(HPWORK, &_work, (worker_t)&ETSAirspeed::cycle_trampoline, this, 1);

	/* notify about state change */
	struct subsystem_info_s info = {
		true,
		true,
		true,
		SUBSYSTEM_TYPE_DIFFPRESSURE
	};
	static orb_advert_t pub = -1;

	if (pub > 0) {
		orb_publish(ORB_ID(subsystem_info), pub, &info);

	} else {
		pub = orb_advertise(ORB_ID(subsystem_info), &info);
	}
}

void
ETSAirspeed::stop()
{
	work_cancel(HPWORK, &_work);
}

void
ETSAirspeed::cycle_trampoline(void *arg)
{
	ETSAirspeed *dev = (ETSAirspeed *)arg;

	dev->cycle();
}

void
ETSAirspeed::cycle()
{
	/* collection phase? */
	if (_collect_phase) {

		/* perform collection */
		if (OK != collect()) {
			log("collection error");
			/* restart the measurement state machine */
			start();
			return;
		}

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

		/*
		 * Is there a collect->measure gap?
		 */
		if (_measure_ticks > USEC2TICK(CONVERSION_INTERVAL)) {

			/* schedule a fresh cycle call when we are ready to measure again */
			work_queue(HPWORK,
				   &_work,
				   (worker_t)&ETSAirspeed::cycle_trampoline,
				   this,
				   _measure_ticks - USEC2TICK(CONVERSION_INTERVAL));

			return;
		}
	}

	/* measurement phase */
	if (OK != measure())
		log("measure error");

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

	/* schedule a fresh cycle call when the measurement is done */
	work_queue(HPWORK,
		   &_work,
		   (worker_t)&ETSAirspeed::cycle_trampoline,
		   this,
		   USEC2TICK(CONVERSION_INTERVAL));
}

void
ETSAirspeed::print_info()
{
	perf_print_counter(_sample_perf);
	perf_print_counter(_comms_errors);
	perf_print_counter(_buffer_overflows);
	printf("poll interval:  %u ticks\n", _measure_ticks);
	printf("report queue:   %u (%u/%u @ %p)\n",
	       _num_reports, _oldest_report, _next_report, _reports);
}

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

/* oddly, ERROR is not defined for c++ */
#ifdef ERROR
# undef ERROR
#endif
const int ERROR = -1;

ETSAirspeed	*g_dev;

void	start(int i2c_bus);
void	stop();
void	test();
void	reset();
void	info();

/**
 * Start the driver.
 */
void
start(int i2c_bus)
{
	int fd;

	if (g_dev != nullptr)
		errx(1, "already started");

	/* create the driver */
	g_dev = new ETSAirspeed(i2c_bus);

	if (g_dev == nullptr)
		goto fail;

	if (OK != g_dev->init())
		goto fail;

	/* set the poll rate to default, starts automatic data collection */
	fd = open(AIRSPEED_DEVICE_PATH, O_RDONLY);

	if (fd < 0)
		goto fail;

	if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0)
		goto fail;

	exit(0);

fail:

	if (g_dev != nullptr) {
		delete g_dev;
		g_dev = nullptr;
	}

	errx(1, "driver start failed");
}

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

	} else {
		errx(1, "driver not running");
	}

	exit(0);
}

/**
 * Perform some basic functional tests on the driver;
 * make sure we can collect data from the sensor in polled
 * and automatic modes.
 */
void
test()
{
	struct differential_pressure_s report;
	ssize_t sz;
	int ret;

	int fd = open(AIRSPEED_DEVICE_PATH, O_RDONLY);

	if (fd < 0)
		err(1, "%s open failed (try 'ets_airspeed start' if the driver is not running", AIRSPEED_DEVICE_PATH);

	/* do a simple demand read */
	sz = read(fd, &report, sizeof(report));

	if (sz != sizeof(report))
		err(1, "immediate read failed");

	warnx("single read");
	warnx("diff pressure: %d pa", report.differential_pressure_pa);

	/* start the sensor polling at 2Hz */
	if (OK != ioctl(fd, SENSORIOCSPOLLRATE, 2))
		errx(1, "failed to set 2Hz poll rate");

	/* 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;
		ret = poll(&fds, 1, 2000);

		if (ret != 1)
			errx(1, "timed out waiting for sensor data");

		/* now go get it */
		sz = read(fd, &report, sizeof(report));

		if (sz != sizeof(report))
			err(1, "periodic read failed");

		warnx("periodic read %u", i);
		warnx("diff pressure: %d pa", report.differential_pressure_pa);
	}

	errx(0, "PASS");
}

/**
 * Reset the driver.
 */
void
reset()
{
	int fd = open(AIRSPEED_DEVICE_PATH, O_RDONLY);

	if (fd < 0)
		err(1, "failed ");

	if (ioctl(fd, SENSORIOCRESET, 0) < 0)
		err(1, "driver reset failed");

	if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0)
		err(1, "driver poll restart failed");

	exit(0);
}

/**
 * Print a little info about the driver.
 */
void
info()
{
	if (g_dev == nullptr)
		errx(1, "driver not running");

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

	exit(0);
}

} // namespace


static void
ets_airspeed_usage()
{
	fprintf(stderr, "usage: ets_airspeed command [options]\n");
	fprintf(stderr, "options:\n");
	fprintf(stderr, "\t-b --bus i2cbus (%d)\n", PX4_I2C_BUS_DEFAULT);
	fprintf(stderr, "command:\n");
	fprintf(stderr, "\tstart|stop|reset|test|info\n");
}

int
ets_airspeed_main(int argc, char *argv[])
{
	int i2c_bus = PX4_I2C_BUS_DEFAULT;

	int i;

	for (i = 1; i < argc; i++) {
		if (strcmp(argv[i], "-b") == 0 || strcmp(argv[i], "--bus") == 0) {
			if (argc > i + 1) {
				i2c_bus = atoi(argv[i + 1]);
			}
		}
	}

	/*
	 * Start/load the driver.
	 */
	if (!strcmp(argv[1], "start"))
		ets_airspeed::start(i2c_bus);

	/*
	 * Stop the driver
	 */
	if (!strcmp(argv[1], "stop"))
		ets_airspeed::stop();

	/*
	 * Test the driver/device.
	 */
	if (!strcmp(argv[1], "test"))
		ets_airspeed::test();

	/*
	 * Reset the driver.
	 */
	if (!strcmp(argv[1], "reset"))
		ets_airspeed::reset();

	/*
	 * Print driver information.
	 */
	if (!strcmp(argv[1], "info") || !strcmp(argv[1], "status"))
		ets_airspeed::info();

	ets_airspeed_usage();
	exit(0);
}