bool sw = false;
int button = 2;
int menu = 4;
int led = 5;
int mode = 1;
byte da_pin = 3;
byte cnt = 0;

void setup() {
  Serial.begin(9600);
  pinMode(button, INPUT_PULLUP);
  pinMode(menu, INPUT_PULLUP);
  pinMode(led, OUTPUT);
  pinMode(da_pin, OUTPUT);
  digitalWrite(da_pin, HIGH);

}

void loop() {
  if(digitalRead(button) == LOW){// if red button has been pressed
    delay(100);
    delay(300);// important
    cnt++;
    if(cnt > 7) {
      cnt = 1;// if cnt is greater than 7, set it back to 1
    }
    folder_play(50 + mode, cnt);
    flash(mode);//falsh xx times
  }

  if(digitalRead(menu) == LOW){
    delay(500);
    sw = true; // turn on the switch of menu
    Serial.println("sw is ON.");
  }

  while(sw == true){//Enter the menu page
    if(digitalRead(button) == LOW){//Selecting button
      delay(500);
      mode++;
      if(mode > 4){//the max of mode is 4
        mode = 1;// back to mode 1
      }
      Serial.print("mode changed to ");
      Serial.println(mode);
    }

    if(digitalRead(menu) == LOW){//Comfirm and exit button
      delay(500);
      sw = false;
      cnt = 0;
      Serial.println("sw is OFF");
      break; // exit the menu loop
    }
  }

}

void flash(int times){
  for(byte i = 0; i < times; i++){
    digitalWrite(led, HIGH);
    delay(300);
    digitalWrite(led, LOW);
    delay(300);
  }
  Serial.println("DONE.");
}

void send_1() {
  digitalWrite(da_pin, HIGH);
  delayMicroseconds(100);
}

void send_0(){
  digitalWrite(da_pin, LOW);
  delayMicroseconds(100);
}

void send_da(uint8_t data){
  digitalWrite(da_pin, LOW);
  delayMicroseconds(100);
  //Start mark
  for(byte i = 0; i < 8; i++){//sending 8 digits
    if(bitRead(data, i) == 0){
      send_0();
    }
    else{
      send_1();
    }
  }
  digitalWrite(da_pin, HIGH);
  delayMicroseconds(100);
  //End mark
}

void folder_play(byte a, byte b){
  byte mp3[8] = {126, 255, 6, 15, (byte)0, a, b, 239};
  for(byte i = 0; i < 8; i++){
    send_da(mp3[i]);
  }
  delay(1);
}