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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 <board_config.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 <drivers/device/ringbuffer.h>

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

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

/* 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 */

class ETSAirspeed : public Airspeed
{
public:
	ETSAirspeed(int bus, int address = I2C_ADDRESS, const char* path = ETS_PATH);

protected:

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

};

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

ETSAirspeed::ETSAirspeed(int bus, int address, const char* path) : Airspeed(bus, address,
	CONVERSION_INTERVAL, path)
{

}

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);
	}

	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) {
		perf_count(_comms_errors);
		return ret;
	}

	uint16_t diff_pres_pa_raw = val[1] << 8 | val[0];
        if (diff_pres_pa_raw == 0) {
		// a zero value means the pressure sensor cannot give us a
		// value. We need to return, and not report a value or the
		// caller could end up using this value as part of an
		// average
		perf_count(_comms_errors);
		log("zero value from sensor"); 
		return -1;
        }

	// The raw value still should be compensated for the known offset
	diff_pres_pa_raw -= _diff_pres_offset;

	// Track maximum differential pressure measured (so we can work out top speed).
	if (diff_pres_pa_raw > _max_differential_pressure_pa) {
		_max_differential_pressure_pa = diff_pres_pa_raw;
	}

	differential_pressure_s report;
	report.timestamp = hrt_absolute_time();
        report.error_count = perf_event_count(_comms_errors);

	// XXX we may want to smooth out the readings to remove noise.
	report.differential_pressure_filtered_pa = diff_pres_pa_raw;
	report.differential_pressure_raw_pa = diff_pres_pa_raw;
	report.temperature = -1000.0f;
	report.max_differential_pressure_pa = _max_differential_pressure_pa;

	if (_airspeed_pub > 0 && !(_pub_blocked)) {
		/* publish it */
		orb_publish(ORB_ID(differential_pressure), _airspeed_pub, &report);
	}

	new_report(report);

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

	ret = OK;

	perf_end(_sample_perf);

	return ret;
}

void
ETSAirspeed::cycle()
{
	int ret;

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

		/* perform collection */
		ret = collect();
		if (OK != ret) {
			perf_count(_comms_errors);
			/* restart the measurement state machine */
			start();
			_sensor_ok = false;
			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)&Airspeed::cycle_trampoline,
				   this,
				   _measure_ticks - USEC2TICK(CONVERSION_INTERVAL));

			return;
		}
	}

	/* measurement phase */
	ret = measure();
	if (OK != ret) {
		debug("measure error");
	}

	_sensor_ok = (ret == OK);

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

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

/**
 * 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.
 *
 * This function only returns if the sensor is up and running
 * or could not be detected successfully.
 */
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->Airspeed::init())
		goto fail;

	/* set the poll rate to default, starts automatic data collection */
	fd = open(AIRSPEED0_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, "no ETS airspeed sensor connected");
}

/**
 * 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(ETS_PATH, O_RDONLY);

	if (fd < 0)
		err(1, "%s open failed (try 'ets_airspeed start' if the driver is not running", ETS_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: %f pa", (double)report.differential_pressure_filtered_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: %f pa", (double)report.differential_pressure_filtered_pa);
	}

	/* reset the sensor polling to its default rate */
	if (OK != ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT))
		errx(1, "failed to set default rate");

	errx(0, "PASS");
}

/**
 * Reset the driver.
 */
void
reset()
{
	int fd = open(ETS_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()
{
	warnx("usage: ets_airspeed command [options]");
	warnx("options:");
	warnx("\t-b --bus i2cbus (%d)", PX4_I2C_BUS_DEFAULT);
	warnx("command:");
	warnx("\tstart|stop|reset|test|info");
}

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);
}