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//-----------------------------------------
//Published by IntroductionToArduino.com
//Created by Paul Illsley (www.paulillsley.com)
//Please use and share so others can enjoy
//-----------------------------------------

// Declaring pin 8 as the ultrasonic sensor's trigger pin (integer)
int trigger_pin = 8;

// Declaring pin 12 as the ultrasonic sensor's echo pin (integer)
int echo_pin = 12;

// Declaring pin 7 as the buzzer pin (integer)
int buzzer_pin = 7;

// Creating a variable to hold the ultrasonic sensor's data stream (floating point)  
float RawData;

// Creating a variable to hold information for the data smoothing process
// A 0 value is required to start the process (floating point)
float OldRawData = 0;

// Creating a variable to hold the filtered (smoothed) data (floating point)
float FilteredData;

// Creating a variable to hold the Distance value (floating point)
float Distance;

void setup() 
{
  // Begin serial port at a baud rate of 9600
  Serial.begin (9600);
  
  // Setting the trigger pin as an output
  pinMode(trigger_pin, OUTPUT);
  
  // Setting the echo pin as an input
  pinMode(echo_pin, INPUT);
  
  // Setting the buzzer pin as an output
  pinMode(buzzer_pin, OUTPUT);
}
 
void loop() 
{
  // Setting the trigger pin to low
  digitalWrite(trigger_pin, LOW);
  
  // delay 1 microseconds
  delayMicroseconds(1);
  
  // Setting the trigger pin to high
  digitalWrite(trigger_pin, HIGH);
  
  // delay 5 microseconds
  delayMicroseconds(5);
  
  // Setting the trigger pin to low
  digitalWrite(trigger_pin, LOW);

  // Populating the RawData variable with the echo data from the ultrasonic sensor
  // Values are milliseconds between the time the sound pulse left the transmitter and returned back to the receiver 
  RawData = pulseIn(echo_pin, HIGH);

  // Calculating the Distance (cm) from the semsor
  Distance = RawData * 0.034 / 2;

  // Filter the RawData to help create a smoother data flow.
  // The OldRawData is given an 80% weight which is added to the RawData having a 20% weight
  // The OldRawData value is derived from original 0 value or created later in the code from the previous loop's FilterdData value 

  FilteredData=.8*OldRawData+.2*RawData;

  // Setting up the serial port's readout format
  // Open the Serial Monitor to view your data values (Tools / Serial Monitor)
  // Open the Serial Plotter to view your data as a graph (Tools / Serial Plotter)
  Serial.print("Raw Data (ms): ");
  Serial.print(RawData);
  Serial.print(", ");
  Serial.print("Distance (cm): ");
  Serial.print(Distance);
  Serial.print(", ");
  Serial.print("Filtered Data (ms): ");
  Serial.print(FilteredData);
  Serial.println();

  // Mapping the buzzer's frequency range for the FilteredData range 
  // Creating a new variable called Sound (integer)
  // Data range is between 50 and 2000
  // Frequency range is between 120 and 1500 megahertz
  // These values can be changed to suit your data and desired frequency ranges
  int Sound = map(FilteredData, 50, 2000, 120, 1500);

  // Sending the remapped data (Sound) to pin 7 (the buzzer)
  tone(7, Sound, 0);

  // Making the variable OldRawData equal to FilteredData to be used in the next loop (for the smoothing process)
  OldRawData=FilteredData;

  //Delay 10 millisecond (then repeat the loop)
  delay(10);        
}
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