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/* =================================================================================================
      Project: Arduino Beatbox
       Author: Scott C
      Created: 9th April 2015
  Arduino IDE: 1.6.2
      Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html
  Description: This project uses home made capacitive sensors to trigger over 130 MP3 sounds
               on the Grove Serial MP3 player. 
               
               The ADCTouch library is used to eliminate the resistors from the Capacitive sensing circuit. 
               The code used for capacitive sensing was adapted from the ADCTouch library example sketches. 
               You can find the ADCTouch library and relevant example code here:
               http://playground.arduino.cc/Code/ADCTouch
               
               "Advanced Arduino ADC" is used to improve the analogRead() speed, and enhance the
               drum pad or capacitive sensor response time. The Advanced Arduino ADC code 
               was adapted from this site:
               http://www.microsmart.co.za/technical/2014/03/01/advanced-arduino-adc/
               
               
=================================================================================================== */
  #include <ADCTouch.h>
  #include <SoftwareSerial.h>
  
  
  //Global variables
  //===================================================================================================
  int potPin = A4;                           //Grove Sliding potentiometer is connected to Analog Pin 4
  int potVal = 0;
  byte mp3Vol = 0;                           //Variable used to control the volume of the MP3 player
  byte oldVol = 0;
  
  int buttonPin = 5;                         //Grove Button is connected to Digital Pin 5
  int buttonStatus = 0;
  
  byte SongNum[4] = {0x01,0x02,0x03,0x04};  //The first 4 songs will be assigned to the drum pads upon initialisation
  byte numOfSongs = 130;                    //Total number of MP3 songs/sounds loaded onto the SDHC card
  
  long randNumber;                          //Variable used to hold the random number - used to randomise the sounds.
  
  int ledState[4];                          //Used to keep track of the status of all LEDs (on or off)
  int counter = 0;
  
  SoftwareSerial mp3(3, 4);                 // The Grove MP3 Player is connected to Arduino digital Pin 3 and 4 (Serial communication)
       
  int ref0, ref1, ref2, ref3;               //reference values to remove offset
  int threshold = 100;
      
  // Define the ADC prescalers
  const unsigned char PS_64 = (1 << ADPS2) | (1 << ADPS1);
  const unsigned char PS_128 = (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
  
  
  
  //Setup()
  //===================================================================================================
  void setup(){
    //Initialise the Grove MP3 Module
    delay(2500);                              //Allow the MP3 module to power up        
    mp3.begin(9600);                          //Begin Serial communication with the MP3 module
    setPlayMode(0x00);                        //0x00 = Single song - played once ie. not repeated.  (default)
    
    //Define the Grove Button as an INPUT
    pinMode(buttonPin, INPUT);
    
    //Define the 4 LED Pins as OUTPUTs
    pinMode(8, OUTPUT);                       //Green LED
    pinMode(9, OUTPUT);                       //Blue LED
    pinMode(10, OUTPUT);                      //Red LED
    pinMode(11, OUTPUT);                      //Yellow LED
    
    //Make sure each LED is OFF, and store the state of the LED into a variable.
    for(int i=8;i<12;i++){
      digitalWrite(i, LOW);
      ledState[i-8]=0;
    } 
    
    //Double our clock speed from 125 kHz to 250 kHz
    ADCSRA &= ~PS_128;   // set up the ADC
    ADCSRA |= PS_64;    // set our own prescaler to 64 
    
    //Create reference values to account for the capacitance of each pad.
    ref0 = ADCTouch.read(A0, 500);
    ref1 = ADCTouch.read(A1, 500);      //Take 500 readings
    ref2 = ADCTouch.read(A2, 500);
    ref3 = ADCTouch.read(A3, 500);
    
     //This helps to randomise the drum pads.
     randomSeed(analogRead(0));
  }
  
  
  
  // Loop()
  //===================================================================================================     
  void loop(){
     
    //Take a reading from the Grove Sliding Potentiometer, and set volume accordingly
    potVal = analogRead(potPin);
    mp3Vol = map(potVal, 0, 1023, 0,31);              // Convert the potentometer reading (0 - 1023) to fit within the MP3 player's Volume range (0 - 31)
    if((mp3Vol>(oldVol+1))|(mp3Vol<(oldVol-1))){      // Only make a change to the Volume on the Grove MP3 player when the potentiometer value changes
      oldVol = mp3Vol;
      setVolume(mp3Vol);
      delay(10);                                      // This delay is necessary with Serial communication to MP3 player
    }
    
    //Take a reading from the Pin attached to the Grove Button. If pressed, randomise the MP3 songs/sounds for each drum pad, and make the LEDs blink randomly.
    buttonStatus = digitalRead(buttonPin);
    if(buttonStatus==HIGH){
      SongNum[0]=randomSongChooser(1, 30);
      SongNum[1]=randomSongChooser(31, 60);
      SongNum[2]=randomSongChooser(61, 86);
      SongNum[3]=randomSongChooser(87, (int)numOfSongs);
      randomLEDBlink();
    }
    
    //Get the capacitive readings from each drum pad: 50 readings are taken from each pad. (default is 100) 
    int value0 = ADCTouch.read(A0,50);        //  Green drum pad
    int value1 = ADCTouch.read(A1,50);        //   Blue drum pad
    int value2 = ADCTouch.read(A2,50);        //    Red drum pad
    int value3 = ADCTouch.read(A3,50);        // Yellow drum pad
    
    //Remove the offset to account for the baseline capacitance of each pad.
    value0 -= ref0;       
    value1 -= ref1;
    value2 -= ref2;
    value3 -= ref3;
    
    
    //If any of the values exceed the designated threshold, then play the song/sound associated with that drum pad.
    //The associated LED will stay on for the whole time the drum pad is pressed, providing the value remains above the threshold. 
    //The LED will turn off when the pad is not being touched or pressed.
    if(value0>threshold){
      digitalWrite(8, HIGH);
      playSong(00,SongNum[0]);
    }else{
      digitalWrite(8,LOW);
    }
    
    if(value1>threshold){
      digitalWrite(9, HIGH);
      playSong(00,SongNum[1]);
    }else{
      digitalWrite(9,LOW);
    }
    
    if(value2>threshold){
      digitalWrite(10, HIGH);
      playSong(00,SongNum[2]);
    }else{
      digitalWrite(10,LOW);
    }
    
    if(value3>threshold){
      digitalWrite(11, HIGH);
      playSong(00,SongNum[3]);
    }else{
      digitalWrite(11,LOW);
    }
  }
      
   
  // writeToMP3: 
  // a generic function that simplifies each of the methods used to control the Grove MP3 Player
  //===================================================================================================
  void writeToMP3(byte MsgLEN, byte A, byte B, byte C, byte D, byte E, byte F){
    byte codeMsg[] = {MsgLEN, A,B,C,D,E,F};
    mp3.write(0x7E);                        //Start Code for every command = 0x7E
    for(byte i = 0; i<MsgLEN+1; i++){
      mp3.write(codeMsg[i]);                //Send the rest of the command to the GROVE MP3 player
    }
  }
  
  
  //setPlayMode: defines how each song is to be played
  //===================================================================================================
  void setPlayMode(byte playMode){
    /* playMode options:
          0x00 = Single song - played only once ie. not repeated.  (default)
          0x01 = Single song - cycled ie. repeats over and over.
          0x02 = All songs - cycled 
          0x03 = play songs randomly                                           */
    writeToMP3(0x03, 0xA9, playMode, 0x7E, 0x00, 0x00, 0x00);  
  }
  
  
  //playSong: tells the Grove MP3 player to play the song/sound, and also which song/sound to play
  //===================================================================================================
  void playSong(byte songHbyte, byte songLbyte){
    writeToMP3(0x04, 0xA0, songHbyte, songLbyte, 0x7E, 0x00, 0x00);            
    delay(100);
  }
  
  
  //setVolume: changes the Grove MP3 player's volume to the designated level (0 to 31)
  //===================================================================================================
  void setVolume(byte Volume){
    byte tempVol = constrain(Volume, 0, 31);             //Volume range = 00 (muted) to 31 (max volume)
    writeToMP3(0x03, 0xA7, tempVol, 0x7E, 0x00, 0x00, 0x00); 
  }
  
  
  //randomSongChooser: chooses a random song to play. The range of songs to choose from
  //is limited and defined by the startSong and endSong parameters.
  //===================================================================================================
  byte randomSongChooser(int startSong, int endSong){
    randNumber = random(startSong, endSong);
    return((byte) randNumber);
  }
  
  
  //randomLEDBlink: makes each LED blink randomly. The LEDs are attached to digital pins 8 to 12.
  //===================================================================================================
  void randomLEDBlink(){
   counter=8;
   for(int i=0; i<40; i++){
     int x = constrain((int)random(8,12),8,12);
     toggleLED(x);
     delay(random(50,100-i));
   }
     
    for(int i=8;i<12;i++){
      digitalWrite(i, HIGH);
    }
    delay(1000);
    for(int i=8;i<12;i++){
      digitalWrite(i, LOW);
      ledState[i-8]=0;
    }
  }
  
  
  //toggleLED: is used by the randomLEDBlink method to turn each LED on and off (randomly).
  //===================================================================================================
  void toggleLED(int pinNum){
    ledState[pinNum-8]= !ledState[pinNum-8];
    digitalWrite(pinNum, ledState[pinNum-8]);
  }
    

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/* =================================================================================================
      Project: Arduino Beatbox
       Author: Scott C
      Created: 9th April 2015
  Arduino IDE: 1.6.2
      Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html
  Description: This project uses home made capacitive sensors to trigger over 130 MP3 sounds
               on the Grove Serial MP3 player. 
               
               The ADCTouch library is used to eliminate the resistors from the Capacitive sensing circuit. 
               The code used for capacitive sensing was adapted from the ADCTouch library example sketches. 
               You can find the ADCTouch library and relevant example code here:
               http://playground.arduino.cc/Code/ADCTouch
               
               "Advanced Arduino ADC" is used to improve the analogRead() speed, and enhance the
               drum pad or capacitive sensor response time. The Advanced Arduino ADC code 
               was adapted from this site:
               http://www.microsmart.co.za/technical/2014/03/01/advanced-arduino-adc/
               
               
=================================================================================================== */
  #include <ADCTouch.h>
  #include <SoftwareSerial.h>
  
  
  //Global variables
  //===================================================================================================
  int potPin = A4;                           //Grove Sliding potentiometer is connected to Analog Pin 4
  int potVal = 0;
  byte mp3Vol = 0;                           //Variable used to control the volume of the MP3 player
  byte oldVol = 0;
  
  int buttonPin = 5;                         //Grove Button is connected to Digital Pin 5
  int buttonStatus = 0;
  
  byte SongNum[4] = {0x01,0x02,0x03,0x04};  //The first 4 songs will be assigned to the drum pads upon initialisation
  byte numOfSongs = 130;                    //Total number of MP3 songs/sounds loaded onto the SDHC card
  
  long randNumber;                          //Variable used to hold the random number - used to randomise the sounds.
  
  int ledState[4];                          //Used to keep track of the status of all LEDs (on or off)
  int counter = 0;
  
  SoftwareSerial mp3(3, 4);                 // The Grove MP3 Player is connected to Arduino digital Pin 3 and 4 (Serial communication)
       
  int ref0, ref1, ref2, ref3;               //reference values to remove offset
  int threshold = 100;
      
  // Define the ADC prescalers
  const unsigned char PS_64 = (1 << ADPS2) | (1 << ADPS1);
  const unsigned char PS_128 = (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
  
  
  
  //Setup()
  //===================================================================================================
  void setup(){
    //Initialise the Grove MP3 Module
    delay(2500);                              //Allow the MP3 module to power up        
    mp3.begin(9600);                          //Begin Serial communication with the MP3 module
    setPlayMode(0x00);                        //0x00 = Single song - played once ie. not repeated.  (default)
    
    //Define the Grove Button as an INPUT
    pinMode(buttonPin, INPUT);
    
    //Define the 4 LED Pins as OUTPUTs
    pinMode(8, OUTPUT);                       //Green LED
    pinMode(9, OUTPUT);                       //Blue LED
    pinMode(10, OUTPUT);                      //Red LED
    pinMode(11, OUTPUT);                      //Yellow LED
    
    //Make sure each LED is OFF, and store the state of the LED into a variable.
    for(int i=8;i<12;i++){
      digitalWrite(i, LOW);
      ledState[i-8]=0;
    } 
    
    //Double our clock speed from 125 kHz to 250 kHz
    ADCSRA &= ~PS_128;   // set up the ADC
    ADCSRA |= PS_64;    // set our own prescaler to 64 
    
    //Create reference values to account for the capacitance of each pad.
    ref0 = ADCTouch.read(A0, 500);
    ref1 = ADCTouch.read(A1, 500);      //Take 500 readings
    ref2 = ADCTouch.read(A2, 500);
    ref3 = ADCTouch.read(A3, 500);
    
     //This helps to randomise the drum pads.
     randomSeed(analogRead(0));
  }
  
  
  
  // Loop()
  //===================================================================================================     
  void loop(){
     
    //Take a reading from the Grove Sliding Potentiometer, and set volume accordingly
    potVal = analogRead(potPin);
    mp3Vol = map(potVal, 0, 1023, 0,31);              // Convert the potentometer reading (0 - 1023) to fit within the MP3 player's Volume range (0 - 31)
    if((mp3Vol>(oldVol+1))|(mp3Vol<(oldVol-1))){      // Only make a change to the Volume on the Grove MP3 player when the potentiometer value changes
      oldVol = mp3Vol;
      setVolume(mp3Vol);
      delay(10);                                      // This delay is necessary with Serial communication to MP3 player
    }
    
    //Take a reading from the Pin attached to the Grove Button. If pressed, randomise the MP3 songs/sounds for each drum pad, and make the LEDs blink randomly.
    buttonStatus = digitalRead(buttonPin);
    if(buttonStatus==HIGH){
      SongNum[0]=randomSongChooser(1, 30);
      SongNum[1]=randomSongChooser(31, 60);
      SongNum[2]=randomSongChooser(61, 86);
      SongNum[3]=randomSongChooser(87, (int)numOfSongs);
      randomLEDBlink();
    }
    
    //Get the capacitive readings from each drum pad: 50 readings are taken from each pad. (default is 100) 
    int value0 = ADCTouch.read(A0,50);        //  Green drum pad
    int value1 = ADCTouch.read(A1,50);        //   Blue drum pad
    int value2 = ADCTouch.read(A2,50);        //    Red drum pad
    int value3 = ADCTouch.read(A3,50);        // Yellow drum pad
    
    //Remove the offset to account for the baseline capacitance of each pad.
    value0 -= ref0;       
    value1 -= ref1;
    value2 -= ref2;
    value3 -= ref3;
    
    
    //If any of the values exceed the designated threshold, then play the song/sound associated with that drum pad.
    //The associated LED will stay on for the whole time the drum pad is pressed, providing the value remains above the threshold. 
    //The LED will turn off when the pad is not being touched or pressed.
    if(value0>threshold){
      digitalWrite(8, HIGH);
      playSong(00,SongNum[0]);
    }else{
      digitalWrite(8,LOW);
    }
    
    if(value1>threshold){
      digitalWrite(9, HIGH);
      playSong(00,SongNum[1]);
    }else{
      digitalWrite(9,LOW);
    }
    
    if(value2>threshold){
      digitalWrite(10, HIGH);
      playSong(00,SongNum[2]);
    }else{
      digitalWrite(10,LOW);
    }
    
    if(value3>threshold){
      digitalWrite(11, HIGH);
      playSong(00,SongNum[3]);
    }else{
      digitalWrite(11,LOW);
    }
  }
      
   
  // writeToMP3: 
  // a generic function that simplifies each of the methods used to control the Grove MP3 Player
  //===================================================================================================
  void writeToMP3(byte MsgLEN, byte A, byte B, byte C, byte D, byte E, byte F){
    byte codeMsg[] = {MsgLEN, A,B,C,D,E,F};
    mp3.write(0x7E);                        //Start Code for every command = 0x7E
    for(byte i = 0; i<MsgLEN+1; i++){
      mp3.write(codeMsg[i]);                //Send the rest of the command to the GROVE MP3 player
    }
  }
  
  
  //setPlayMode: defines how each song is to be played
  //===================================================================================================
  void setPlayMode(byte playMode){
    /* playMode options:
          0x00 = Single song - played only once ie. not repeated.  (default)
          0x01 = Single song - cycled ie. repeats over and over.
          0x02 = All songs - cycled 
          0x03 = play songs randomly                                           */
    writeToMP3(0x03, 0xA9, playMode, 0x7E, 0x00, 0x00, 0x00);  
  }
  
  
  //playSong: tells the Grove MP3 player to play the song/sound, and also which song/sound to play
  //===================================================================================================
  void playSong(byte songHbyte, byte songLbyte){
    writeToMP3(0x04, 0xA0, songHbyte, songLbyte, 0x7E, 0x00, 0x00);            
    delay(100);
  }
  
  
  //setVolume: changes the Grove MP3 player's volume to the designated level (0 to 31)
  //===================================================================================================
  void setVolume(byte Volume){
    byte tempVol = constrain(Volume, 0, 31);             //Volume range = 00 (muted) to 31 (max volume)
    writeToMP3(0x03, 0xA7, tempVol, 0x7E, 0x00, 0x00, 0x00); 
  }
  
  
  //randomSongChooser: chooses a random song to play. The range of songs to choose from
  //is limited and defined by the startSong and endSong parameters.
  //===================================================================================================
  byte randomSongChooser(int startSong, int endSong){
    randNumber = random(startSong, endSong);
    return((byte) randNumber);
  }
  
  
  //randomLEDBlink: makes each LED blink randomly. The LEDs are attached to digital pins 8 to 12.
  //===================================================================================================
  void randomLEDBlink(){
   counter=8;
   for(int i=0; i<40; i++){
     int x = constrain((int)random(8,12),8,12);
     toggleLED(x);
     delay(random(50,100-i));
   }
     
    for(int i=8;i<12;i++){
      digitalWrite(i, HIGH);
    }
    delay(1000);
    for(int i=8;i<12;i++){
      digitalWrite(i, LOW);
      ledState[i-8]=0;
    }
  }
  
  
  //toggleLED: is used by the randomLEDBlink method to turn each LED on and off (randomly).
  //===================================================================================================
  void toggleLED(int pinNum){
    ledState[pinNum-8]= !ledState[pinNum-8];
    digitalWrite(pinNum, ledState[pinNum-8]);
  }
    

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/* ===============================================================================
      Project: Grove Serial MP3 Player overview
       Author: Scott C
      Created: 9th March 2015
  Arduino IDE: 1.6.0
      Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html

  Description: The following Arduino sketch will allow you to control a Grove Serial MP3 player
               with a Grove Sliding Potentiometer (volume), a Grove button (next song), 
               and a Grove Switch (on/off). It will also show you how to retrieve some useful information from the player. 
               Some functions are not used in this sketch,but have been included for your benefit. 
               
               Additional features and functionality can be found on the WT5001 voice chip datasheet 
               which I retrieved from here: http://goo.gl/ai6oQ9
               
               The Seeedstudio wiki was a very useful resource for getting started with the various Grove modules:
               http://goo.gl/xOiSCl
=============================================================================== */

#include <SoftwareSerial.h>
SoftwareSerial mp3(2, 3);      // The Grove MP3 Player is connected to Arduino digital Pin 2 and 3 (Serial communication)
int potPin = A0;               // The Sliding Potentiometer is connected to AnalogPin 0
int potVal = 0;                // This is used to hold the value of the Sliding Potentiometer
byte mp3Vol = 0;               // mp3Vol is used to calculate the Current volume of the Grove MP3 player
byte oldVol = 0;               // oldVol is used to remember the previous volume level
int ledPin = A1;               // The Grove sliding potentiometer has an onboard LED attached to Analog pin 1.

int switchPin = 12;             // The Grove Switch(P) is connected to digital Pin 12
int switchStatus = 0;           // This is used to hold the status of the switch 
int switchChangeStatus = 0;     // Used to identify when the switch status has changed

int buttonPin = 5;              // The Grove Button is connected to digital pin 5
int buttonStatus = 0;           // This is used to hold the status of the button  



void setup(){
  //Initialise the Grove MP3 Module
  delay(2500);
  mp3.begin(9600);
  
        
  // initialize the pushbutton and switch pin as an input:
  pinMode(buttonPin, INPUT);
  pinMode(switchPin, INPUT);
  
  // set ledPin on the sliding potentiometer to OUTPUT
  pinMode(ledPin, OUTPUT);
  
  //You can view the following demostration output in the Serial Monitor
  demonstrate_GET_FUNCTIONS();     
}


void loop(){
  switchStatus = digitalRead(switchPin);
  if(switchStatus==HIGH){
    if(switchChangeStatus==LOW){             // When Arduino detects a change in the switchStatus (from LOW to HIGH) - play song      
      setPlayMode(0x02);                     // Automatically cycle to the next song when the current song ends
      playSong(00,01);                       // Play the 1st song when you switch it on
      switchChangeStatus=HIGH;
    }
    
    potVal = analogRead(potPin);                      // Analog read values from the sliding potentiometer range from 0 to 1023
    analogWrite(ledPin, potVal/4);                    // Analog write values range from 0 to 255, and will turn LED ON once potentiometer reaches about half way (or more).
    mp3Vol = map(potVal, 0, 1023, 0,31);              // Convert the potentometer reading (0 - 1023) to fit within the MP3 player's Volume range (0 - 31)
    if((mp3Vol>(oldVol+1))|(mp3Vol<(oldVol-1))){      // Only make a change to the Volume on the Grove MP3 player when the potentiometer value changes
      oldVol = mp3Vol;
      setVolume(mp3Vol);
      delay(10);                               // This delay is necessary with Serial communication to MP3 player
    }

    buttonStatus = digitalRead(buttonPin);
    if(buttonStatus==HIGH){                    // When a button press is detected - play the next song
      playNextSong();
      delay(200);                              // This delay aims to prevent a "skipped" song due to slow button presses - can modify to suit.
    }
  } else {
    if(switchChangeStatus==HIGH){              // When switchStatus changes from HIGH to LOW - stop Song.
      stopSong();
      switchChangeStatus=LOW;
    }
  } 
}


// demonstrate_GET_FUNCTIONS  will show you how to retrieve some useful information from the Grove MP3 Player (using the Serial Monitor).
void demonstrate_GET_FUNCTIONS(){
        Serial.begin(9600);
        Serial.print("Volume: ");
        Serial.println(getVolume());
        Serial.print("Playing State: ");
        Serial.println(getPlayingState());
        Serial.print("# of Files in SD Card:");
        Serial.println(getNumberOfFiles());
        Serial.println("------------------------------");
}


// writeToMP3: is a generic function that aims to simplify all of the methods that control the Grove MP3 Player

void writeToMP3(byte MsgLEN, byte A, byte B, byte C, byte D, byte E, byte F){
  byte codeMsg[] = {MsgLEN, A,B,C,D,E,F};
  mp3.write(0x7E);                        //Start Code for every command = 0x7E
  for(byte i = 0; i<MsgLEN+1; i++){
    mp3.write(codeMsg[i]);                //Send the rest of the command to the GROVE MP3 player
  }
}


/* The Following functions control the Grove MP3 Player : see datasheet for additional functions--------------------------------------------*/

void setPlayMode(byte playMode){
  /* playMode options:
        0x00 = Single song - played only once ie. not repeated.  (default)
        0x01 = Single song - cycled ie. repeats over and over.
        0x02 = All songs - cycled 
        0x03 = play songs randomly                                           */
        
  writeToMP3(0x03, 0xA9, playMode, 0x7E, 0x00, 0x00, 0x00);  
}


void playSong(byte songHbyte, byte songLbyte){                              // Plays the selected song
  writeToMP3(0x04, 0xA0, songHbyte, songLbyte, 0x7E, 0x00, 0x00);            
}


void pauseSong(){                                                           // Pauses the current song
  writeToMP3(0x02, 0xA3, 0x7E, 0x00, 0x00, 0x00, 0x00);
}


void stopSong(){                                                            // Stops the current song
  writeToMP3(0x02, 0xA4, 0x7E, 0x00, 0x00, 0x00, 0x00);
}


void playNextSong(){                                                        // Play the next song
  writeToMP3(0x02, 0xA5, 0x7E, 0x00, 0x00, 0x00, 0x00);
}


void playPreviousSong(){                                                    // Play the previous song
  writeToMP3(0x02, 0xA6, 0x7E, 0x00, 0x00, 0x00, 0x00);
}


void addSongToPlayList(byte songHbyte, byte songLbyte){
  //Repeat this function for every song you wish to stack onto the playlist (max = 10 songs)
  writeToMP3(0x04, 0xA8, songHbyte, songLbyte, 0x7E, 0x00, 0x00);
}


void setVolume(byte Volume){                                                // Set the volume
  byte tempVol = constrain(Volume, 0, 31);
  //Volume range = 00 (muted) to 31 (max volume)
  writeToMP3(0x03, 0xA7, tempVol, 0x7E, 0x00, 0x00, 0x00); 
}



/* The following functions retrieve information from the Grove MP3 player : see data sheet for additional functions--------------*/

// getData: is a generic function to simplifly the other functions for retieving information from the Grove Serial MP3 player
byte getData(byte queryVal, int dataPosition){
  byte returnVal = 0x00;
  writeToMP3(0x02, queryVal, 0x7E, 0x00, 0x00, 0x00, 0x00);
  delay(50);
  for(int x = 0; x<dataPosition; x++){
    if(mp3.available()){
      returnVal = mp3.read();
      delay(50);
    }
  }
  return(returnVal);
}

byte getVolume(){                                              //Get the volume of the Grove Serial MP3 player
  //returns value from 0 - 31
  return(getData(0xC1, 4));
}

byte getPlayingState(){                                        //Get the playing state : Play / Stopped / Paused
  //returns 1: Play,   2: Stop,   3:Paused
  return(getData(0xC2, 2));
}


byte getNumberOfFiles(){                                      //Find out how many songs are on the SD card
  //returns the number of MP3 files on SD card
  return(getData(0xC4, 3));
}