#include <LiquidCrystal_I2C.h>
#include "MyButton.h"
#include "BT201.h"
LiquidCrystal_I2C lcd(0x27, 16, 2);

Button b[4] = {Button(2, INPUT_PULLUP), Button(3, INPUT_PULLUP), Button(4, INPUT_PULLUP), Button(5, INPUT_PULLUP)};

BT201 bt;
void setup() {
  bt.init();
  lcd.init();
  lcd.backlight();

}
bool mode;
void loop() {
  b[0].ShortPress([]() {
    bt.nextTrack();
  });
  b[1].ShortPress([]() {
    bt.prevTrack();
  });
  b[2].ShortPress([]() {
    bt.play_pause();
  });

  b[3].ShortPress([]() {
    mode = !mode;
    bt.switchMode(mode ? 'U' : 'B');
  });

  bt.getDataFromBt();
  lcd.setCursor(0, 0);
  lcd.print(bt.FileName.substring(0, 16));
  lcd.setCursor(0, 1);
  lcd.print(bt.FileName.substring(16) + "          ");

}


sketch.ino

diagram.json

# Wokwi Library List
# See https://docs.wokwi.com/guides/libraries

# Automatically added based on includes:
LiquidCrystal I2C



libraries.txt

/*Library written by VIJIL JOY*/
#ifndef MYBUTTON_H
#define MYBUTTON_h
class Button{
bool b=1;
unsigned long lastDebounceTime = 0;  
unsigned long debounceDelay = 1; 
int buttonState=0;        
int lastButtonState = 0; 
unsigned long  timer;
int t;
int pin;
public:
Button(int p,int mode){
  pin=p;
  pinMode(p,mode);
}
void ShortPress(void(*callback)()) {
  int reading = digitalRead(pin);
  if (reading != lastButtonState) {
    t=0;
    lastDebounceTime = millis();
  }
  if ((millis() - lastDebounceTime) > debounceDelay) {
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == 1 ) {
        if(b==0){
          t=0;
        callback();
        }
        b=0;
      }
    }
  }
  lastButtonState = reading;
}

void longPress(void(*callback)(),int d){
  if(digitalRead(pin)==0){
    if(millis()-timer>=1000){
      timer = millis();
      t++;
      if(t>d){
        t=0;b=1;
        callback();
      }
    }
  }
}
};
#endif

MyButton.h

class BT201 {

  public:


    String BufferData, FileName;
    void init() {
      Serial.begin(115200);
    }
    void getDataFromBt() {
      if (Serial.available())
      {
        BufferData = Serial.readString();
        FileName = BufferData.substring(BufferData.indexOf("MF+") + 3);
      }
    }

    void send(String cmd, char t = 0) {
      if (t == 0)Serial.print("AT+" + cmd + "\r\n");
      else {
        Serial.print("AT+" + cmd + "[\r]\n");
      }
    }

    void setName(String name) {
      send("BD" + name);
    }

    void nextTrack() {
      send("CC");
    }

    void prevTrack() {
      send("CD");
    }

    void play_pause() {
      send("CB");
    }

    void switchMode(char m) {
      if (m == 'B')send("CM01");
      if (m == 'U')send("CM02");
      if (m == 'S')send("CM03");
      if (m == 'A')send("CM05");

    }

};