PX4-Autopilot/src/drivers/ll40ls/LidarLitePWM.cpp

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/**
 * @file LidarLitePWM.h
 * @author Johan Jansen <jnsn.johan@gmail.com>
 * @author Ban Siesta <bansiesta@gmail.com>
 *
 * Driver for the PulsedLight Lidar-Lite range finders connected via PWM.
 *
 * This driver accesses the pwm_input published by the pwm_input driver.
 */

#include "LidarLitePWM.h"
#include <stdio.h>
#include <string.h>
#include <drivers/drv_hrt.h>
#include <drivers/drv_pwm_input.h>

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

LidarLitePWM::LidarLitePWM(const char *path) :
	CDev("LidarLitePWM", path),
	_work{},
	_reports(nullptr),
	_class_instance(-1),
	_orb_class_instance(-1),
	_pwmSub(-1),
	_pwm{},
	_distance_sensor_topic(nullptr),
	_range{},
	_sample_perf(perf_alloc(PC_ELAPSED, "ll40ls_pwm_read")),
	_read_errors(perf_alloc(PC_COUNT, "ll40ls_pwm_read_errors")),
	_buffer_overflows(perf_alloc(PC_COUNT, "ll40ls_pwm_buffer_overflows")),
	_sensor_zero_resets(perf_alloc(PC_COUNT, "ll40ls_pwm_zero_resets"))
{
}

LidarLitePWM::~LidarLitePWM()
{
	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(_buffer_overflows);
	perf_free(_sensor_zero_resets);
}


int LidarLitePWM::init()
{
	/* do regular cdev init */
	int ret = CDev::init();

	if (ret != OK) {
		return ERROR;
	}

	/* allocate basic report buffers */
	_reports = new ringbuffer::RingBuffer(2, sizeof(struct distance_sensor_s));

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

	_class_instance = register_class_devname(RANGE_FINDER_BASE_DEVICE_PATH);

	/* get a publish handle on the distance_sensor topic */
	struct distance_sensor_s ds_report = {};
	measure();
	_reports->get(&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) {
		DEVICE_DEBUG("failed to create distance_sensor object. Did you start uOrb?");
	}

	return OK;
}

void LidarLitePWM::print_info()
{
	perf_print_counter(_sample_perf);
	perf_print_counter(_read_errors);
	perf_print_counter(_buffer_overflows);
	perf_print_counter(_sensor_zero_resets);
	warnx("poll interval:  %u ticks", getMeasureTicks());
	warnx("distance: %.3fm", (double)_range.current_distance);
}

void LidarLitePWM::print_registers()
{
	printf("Not supported in PWM mode\n");
}

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

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

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

	dev->cycle();
}

void LidarLitePWM::cycle()
{
	measure();

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

int LidarLitePWM::measure()
{
	perf_begin(_sample_perf);

	if (OK != collect()) {
		DEVICE_DEBUG("collection error");
		perf_count(_read_errors);
		perf_end(_sample_perf);
		return ERROR;
	}

	_range.timestamp = hrt_absolute_time();
	_range.type = distance_sensor_s::MAV_DISTANCE_SENSOR_LASER;
	_range.max_distance = get_maximum_distance();
	_range.min_distance = get_minimum_distance();
	_range.current_distance = float(_pwm.pulse_width) * 1e-3f;   /* 10 usec = 1 cm distance for LIDAR-Lite */
	_range.covariance = 0.0f;
	_range.orientation = 8;
	/* TODO: set proper ID */
	_range.id = 0;

	/* Due to a bug in older versions of the LidarLite firmware, we have to reset sensor on (distance == 0) */
	if (_range.current_distance <= 0.0f) {
		perf_count(_sensor_zero_resets);
		perf_end(_sample_perf);
		return reset_sensor();
	}

	if (_distance_sensor_topic != nullptr) {
		orb_publish(ORB_ID(distance_sensor), _distance_sensor_topic, &_range);
	}

	if (_reports->force(&_range)) {
		perf_count(_buffer_overflows);
	}

	poll_notify(POLLIN);
	perf_end(_sample_perf);
	return OK;
}

ssize_t LidarLitePWM::read(struct file *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 (getMeasureTicks() > 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;

	} else {

		_reports->flush();
		measure();

		if (_reports->get(rbuf)) {
			ret = sizeof(*rbuf);
		}
	}

	return ret;
}

int
LidarLitePWM::ioctl(struct file *filp, int cmd, unsigned long arg)
{
	switch (cmd) {
	/* no custom ioctls implemented for now */
	default:
		/* give it to the superclass */
		return LidarLite::ioctl(filp, cmd, arg);
	}
}

int LidarLitePWM::collect()
{
	int fd = ::open(PWMIN0_DEVICE_PATH, O_RDONLY);

	if (fd == -1) {
		return ERROR;
	}

	if (::read(fd, &_pwm, sizeof(_pwm)) == sizeof(_pwm)) {
		::close(fd);
		return OK;
	}

	::close(fd);
	return EAGAIN;
}

int LidarLitePWM::reset_sensor()
{

	int fd = ::open(PWMIN0_DEVICE_PATH, O_RDONLY);

	if (fd == -1) {
		return ERROR;
	}

	int ret = ::ioctl(fd, SENSORIOCRESET, 0);
	::close(fd);
	return ret;
}