/* 
 * rosserial IR Ranger Example  
 * 
 * This example is calibrated for the Sharp GP2D120XJ00F.
 */

#include <ros.h>
#include <ros/time.h>
#include <sensor_msgs/Range.h>

ros::NodeHandle  nh;


sensor_msgs::Range range_msg;
ros::Publisher pub_range( "range_data", &range_msg);

const int analog_pin = 0;
unsigned long range_timer;

/*
 * getRange() - samples the analog input from the ranger
 * and converts it into meters.  
 */
float getRange(int pin_num){
    int sample;
    // Get data
    sample = analogRead(pin_num)/4;
    // if the ADC reading is too low, 
    //   then we are really far away from anything
    if(sample < 10)
        return 254;     // max range
    // Magic numbers to get cm
    sample= 1309/(sample-3);
    return (sample - 1)/100; //convert to meters
}

char frameid[] = "/ir_ranger";

void setup()
{
  nh.initNode();
  nh.advertise(pub_range);
  
  range_msg.radiation_type = sensor_msgs::Range::INFRARED;
  range_msg.header.frame_id =  frameid;
  range_msg.field_of_view = 0.01;
  range_msg.min_range = 0.03;
  range_msg.max_range = 0.4;
  
}

void loop()
{
  // publish the range value every 50 milliseconds
  //   since it takes that long for the sensor to stabilize
  if ( (millis()-range_timer) > 50){
    range_msg.range = getRange(analog_pin);
    range_msg.header.stamp = nh.now();
    pub_range.publish(&range_msg);
    range_timer =  millis() + 50;
  }
  nh.spinOnce();
}