Touch_MP3.ino - touch triggered MP3 playback -
the code allows for audio to be triggered by touch but what do I need to change in order for the audio to ONLY play when being touched? And for it start back at the begging when contact is lost and regained on the sensor?
any help please 
// compiler error handling
#include "Compiler_Errors.h"
// touch includes
#include <MPR121.h>
#include <Wire.h>
#define MPR121_ADDR 0x5C
#define MPR121_INT 4
// mp3 includes
#include <SPI.h>
#include <SdFat.h>
#include <SdFatUtil.h>
#include <SFEMP3Shield.h>
// mp3 variables
SFEMP3Shield MP3player;
byte result;
int lastPlayed = 0;
// mp3 behaviour defines
#define REPLAY_MODE TRUE // By default, touching an electrode repeatedly will
// play the track again from the start each time.
//
// If you set this to FALSE, repeatedly touching an
// electrode will stop the track if it is already
// playing, or play it from the start if it is not.
// touch behaviour definitions
#define firstPin 0
#define lastPin 11
// sd card instantiation
SdFat sd;
void setup(){
Serial.begin(57600);
pinMode(LED_BUILTIN, OUTPUT);
//while (!Serial) ; {} //uncomment when using the serial monitor
Serial.println("Bare Conductive Touch MP3 player");
if(!sd.begin(SD_SEL, SPI_HALF_SPEED)) sd.initErrorHalt();
if(!MPR121.begin(MPR121_ADDR)) Serial.println("error setting up MPR121");
MPR121.setInterruptPin(MPR121_INT);
MPR121.setTouchThreshold(40);
MPR121.setReleaseThreshold(20);
result = MP3player.begin();
MP3player.setVolume(10,10);
if(result != 0) {
Serial.print("Error code: ");
Serial.print(result);
Serial.println(" when trying to start MP3 player");
}
}
void loop(){
readTouchInputs();
}
void readTouchInputs(){
if(MPR121.touchStatusChanged()){
MPR121.updateTouchData();
// only make an action if we have one or fewer pins touched
// ignore multiple touches
if(MPR121.getNumTouches()<=1){
for (int i=0; i < 12; i++){ // Check which electrodes were pressed
if(MPR121.isNewTouch(i)){
//pin i was just touched
Serial.print("pin ");
Serial.print(i);
Serial.println(" was just touched");
digitalWrite(LED_BUILTIN, HIGH);
if(i<=lastPin && i>=firstPin){
if(MP3player.isPlaying()){
if(lastPlayed==i && !REPLAY_MODE){
// if we're already playing the requested track, stop it
// (but only if we're in REPLAY_MODE)
MP3player.stopTrack();
Serial.print("stopping track ");
Serial.println(i-firstPin);
} else {
// if we're already playing a different track (or we're in
// REPLAY_MODE), stop and play the newly requested one
MP3player.stopTrack();
MP3player.playTrack(i-firstPin);
Serial.print("playing track ");
Serial.println(i-firstPin);
// don't forget to update lastPlayed - without it we don't
// have a history
lastPlayed = i;
}
} else {
// if we're playing nothing, play the requested track
// and update lastplayed
MP3player.playTrack(i-firstPin);
Serial.print("playing track ");
Serial.println(i-firstPin);
lastPlayed = i;
}
}
}else{
if(MPR121.isNewRelease(i)){
Serial.print("pin ");
Serial.print(i);
Serial.println(" is no longer being touched");
digitalWrite(LED_BUILTIN, LOW);
}
}
}
}
}
}