hlds_lds2_publisher.cpp

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 /* Authors: SP Kong, Jeehoon Yang */
 /* maintainer: Jeehoon Yang */

#include <ros/ros.h>
#include <sensor_msgs/LaserScan.h>
#include <boost/asio.hpp>
#include <hls_lfcd_lds2_driver/lfcd_lds2.h>
#include <std_msgs/UInt16.h>

namespace hls_lfcd_lds2
{
LFCDLaser::LFCDLaser(const std::string& port, uint32_t baud_rate, boost::asio::io_service& io)
  : port_(port), baud_rate_(baud_rate), shutting_down_(false), serial_(io, port_)
{
  serial_.set_option(boost::asio::serial_port_base::baud_rate(baud_rate_));

  boost::asio::write(serial_, boost::asio::buffer("b", 1));  // start motor
}

LFCDLaser::~LFCDLaser()
{
  boost::asio::write(serial_, boost::asio::buffer("e", 1));  // stop motor
  boost::asio::write(serial_, boost::asio::buffer("e", 1));  // stop motor
}

void LFCDLaser::poll(sensor_msgs::LaserScan::Ptr scan)
{
  uint8_t temp_char;
  uint8_t start_count = 0;
  bool got_scan = false;
  boost::array<uint8_t, 1980> raw_bytes;
  uint8_t good_sets = 0;
  uint32_t motor_speed = 0;
  rpms=0;
  int index;

  while (!shutting_down_ && !got_scan)
  {
    // Wait until first data sync of frame: 0xFA, 0xA0
    boost::asio::read(serial_, boost::asio::buffer(&raw_bytes[start_count],1));

    if(start_count == 0)
    {
      if(raw_bytes[start_count] == 0xFA)
      {
        start_count = 1;
      }
    }
    else if(start_count == 1)
    {
      if(raw_bytes[start_count] == 0xA0)
      {
        start_count = 0;

        // Now that entire start sequence has been found, read in the rest of the message
        got_scan = true;

        boost::asio::read(serial_,boost::asio::buffer(&raw_bytes[2], 1978));

        scan->angle_min = 0.0;
        scan->angle_max = 2.0*M_PI-scan->angle_increment;
        scan->angle_increment = (2.0*M_PI/360.0);
        scan->range_min = 0.12;
        scan->range_max = 5.0;
        scan->ranges.resize(360);
        scan->intensities.resize(360);

        //read data in sets of 4
        for(uint16_t i = 0; i < raw_bytes.size(); i=i+22)
        {
          if(raw_bytes[i] == 0xFA && raw_bytes[i+1] == (0xA0 + i / 22))
          {
            good_sets++;
            motor_speed += (raw_bytes[i+3] << 8) + raw_bytes[i+2];
            rpms=(raw_bytes[i+3]<<8|raw_bytes[i+2])/10;

            for(uint16_t j = i+4; j < i+20; j=j+4)
            {
              index = 4*(i/22) + (j-4-i)/4;

              // Four bytes per reading
              uint8_t byte0 = raw_bytes[j];
              uint8_t byte1 = raw_bytes[j+1];
              uint8_t byte2 = raw_bytes[j+2];
              uint8_t byte3 = raw_bytes[j+3];

              // Remaining bits are the range in mm
              uint16_t range = ((byte1 & 0x3F)<< 8) + byte0;

              // Last two bytes represent the uncertanty or intensity, might also be pixel area of target...
              uint16_t intensity = (byte3 << 8) + byte2;

              scan->ranges[359-index] = range / 1000.0;
              scan->intensities[359-index] = intensity;
            }
          }
        }

        scan->time_increment = motor_speed/good_sets/1e8;
      }
      else
      {
        start_count = 0;
      }
    }
  }
}
}

int main(int argc, char **argv)
{
  ros::init(argc, argv, "hlds_lds2_publisher");
  ros::NodeHandle n;
  ros::NodeHandle priv_nh("~");

  std::string port;
  int baud_rate;
  std::string frame_id;

  std_msgs::UInt16 rpms;

  priv_nh.param("port", port, std::string("/dev/ttyUSB0"));
  priv_nh.param("baud_rate", baud_rate, 115200);
  priv_nh.param("frame_id", frame_id, std::string("laser"));

  boost::asio::io_service io;

  try
  {
    hls_lfcd_lds2::LFCDLaser laser(port, baud_rate, io);
    ros::Publisher laser_pub = n.advertise<sensor_msgs::LaserScan>("scan", 1000);
    ros::Publisher motor_pub = n.advertise<std_msgs::UInt16>("rpms",1000);

    while (ros::ok())
    {
      sensor_msgs::LaserScan::Ptr scan(new sensor_msgs::LaserScan);
      scan->header.frame_id = frame_id;
      laser.poll(scan);
      scan->header.stamp = ros::Time::now();
      rpms.data=laser.rpms;
      laser_pub.publish(scan);
      motor_pub.publish(rpms);
    }
    laser.close();

    return 0;
  }
  catch (boost::system::system_error ex)
  {
    ROS_ERROR("An exception was thrown: %s", ex.what());
    return -1;
  }
}