/*
 * 
 * 
This is Arduino code to measure the distance using Sharp Infrared Distance
sensor GP2Y0A51SK0F to measure from 2 to 14 cm.

See datasheet 
https://global.sharp/products/device/lineup/data/pdf/datasheet/gp2y0a51sk_e.pdf
 * 
 * Watch video instructions for this code:  https://youtu.be/rdNCIyL6OA8
 * 

 * Written by Ahmad Shamshiri on July 09, 2020 in Ajax, Ontario, Canada
 * 
 * Get this code and other Arduino codes from Robojax.com.
Learn Arduino step by step in a structured course with all material, wiring diagrams, and libraries
all in one place. 

If you found this tutorial helpful, please support me so I can continue creating 
content like this. 

or make a donation using PayPal http://robojax.com/L/?id=64
Related videos:
Introduction to MAX6675 K-Type: https://youtu.be/VGqONmUinqA
Using MAX6675 K-Type thermocouple with LED display: https://youtu.be/cD5oOu4N_AE
Using MAX6675 K-Type thermocouple with LCD1602-I2C: https://youtu.be/BlhpktgPdKs
Using 2 or more MAX6675 K-Type thermocouples: https://youtu.be/c90NszbNG8c
Using MAX6675 K-Type thermocouple as heater or cooler controller: [this video]
 *  * This code is "AS IS" without warranty or liability. Free to be used as long as you keep this note intact.* 
 * This code has been downloaded from Robojax.com
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.


*/

//33.9 + -69.5x + 62.3x^2 + -25.4x^3 + 3.83x^4


const int sensorPin[] = {A0};
float distance[1];//watch video for details https://youtu.be/rdNCIyL6OA8
const int AVERAGE_OF =50;
const float MCU_VOLTAGE = 5.0;

void setup()
{
 //Robojax.com code for sharp IR sensor 
  Serial.begin(9600); 
  Serial.println("Robojax Sharp GP2Y0A51SK0F demo");
 //Robojax.com code for sharp IR sensor 
}//setup ends here



void loop(){
   //Robojax.com code for sharp IR sensor 
   readDistance(0);//read sensor 1
   // readDistance(1);//read sensor 2
   if(distance[0] >8.5)
   {
    //if distance is greater than 8.5 do something here
   }

  // print out the value you read:
  Serial.print("d1 =");// 
  Serial.print(distance[0]);
  Serial.println("cm");
  delay(300);
 //Robojax.com code for sharp IR sensor 
}//loop end


/*
 *  readDistance()
 * @brief reads the distance from the sharp sensor
 * and updates the appropriate sensor's value
 * @param "sensor" is an integer

 * @return none
 * Written by Ahmad Shamshiri for robojax.com
 * on July 09, 2020 in Ajax, Ontario, Canada
 */
void readDistance(int sensor)
{
  //Robojax.com code for sharp IR sensor 
      float voltage_temp_average=0;
      
      for(int i=0; i < AVERAGE_OF; i++)
    {
      int sensorValue = analogRead(sensorPin[sensor] );
      delay(1);      
      voltage_temp_average +=sensorValue * (MCU_VOLTAGE / 1023.0);

    }
     voltage_temp_average /= AVERAGE_OF;

  // equation of the fitting curve
  ////33.9 + -69.5x + 62.3x^2 + -25.4x^3 + 3.83x^4
  distance[sensor] = 33.9 + -69.5*(voltage_temp_average) + 62.3*pow(voltage_temp_average,2) + -25.4*pow(voltage_temp_average,3) + 3.83*pow(voltage_temp_average,4);
  
     //Robojax.com code for sharp IR sensor 
}//readDistance