http://arduino-kit.ru/textpage_ws/pages_ws/proekt-28_--schityivatel-rfid-na-primere-rc522.-printsip-rabotyi-podklyuchenie

http://iarduino.ru/file/123.html

https://github.com/miguelbalboa/rfid

http://iarduino.ru/file/140.html

http://iarduino.ru/file/191.html

/*
 * MFRC522 - Library to use ARDUINO RFID MODULE KIT 13.56 MHZ WITH TAGS SPI W AND R BY COOQROBOT.
 * The library file MFRC522.h has a wealth of useful info. Please read it.
 * The functions are documented in MFRC522.cpp.
 *
 * Based on code Dr.Leong   ( WWW.B2CQSHOP.COM )
 * Created by Miguel Balboa (circuitito.com), Jan, 2012.
 * Rewritten by Søren Thing Andersen (access.thing.dk), fall of 2013 (Translation to English, refactored, comments, anti collision, cascade levels.)
 * Released into the public domain.
 *
 * Sample program showing how to read data from a PICC using a MFRC522 reader on the Arduino SPI interface.
 *----------------------------------------------------------------------------- empty_skull 
 * Aggiunti pin per arduino Mega
 * add pin configuration for arduino mega
 * http://mac86project.altervista.org/
 ----------------------------------------------------------------------------- Nicola Coppola
 * Pin layout should be as follows:
 * Signal     Pin              Pin               Pin
 *            Arduino Uno      Arduino Mega      MFRC522 board
 * ------------------------------------------------------------
 * Reset      9                5                 RST
 * SPI SS     10               53                SDA
 * SPI MOSI   11               51                MOSI
 * SPI MISO   12               50                MISO
 * SPI SCK    13               52                SCK
 *
 * The reader can be found on eBay for around 5 dollars. Search for "mf-rc522" on ebay.com. 
 */

#include <SPI.h>
#include <MFRC522.h>

#define SS_PIN 10
#define RST_PIN 9
MFRC522 mfrc522(SS_PIN, RST_PIN);	// Create MFRC522 instance.

void setup() {
	Serial.begin(9600);	// Initialize serial communications with the PC
	SPI.begin();			// Init SPI bus
	mfrc522.PCD_Init();	// Init MFRC522 card
	Serial.println("Scan PICC to see UID and type...");
}

void loop()
{
if ( ! mfrc522.PICC_IsNewCardPresent())
return;
// чтение карты
if ( ! mfrc522.PICC_ReadCardSerial())
return;
// показать результат чтения UID и тип метки
Serial.print(F("Card UID:"));
dump_byte_array(mfrc522.uid.uidByte, mfrc522.uid.size);
Serial.println();
Serial.print(F("PICC type: "));
byte piccType = mfrc522.PICC_GetType(mfrc522.uid.sak);
Serial.println(mfrc522.PICC_GetTypeName(piccType));
delay(2000);
}
// Вывод результата чтения данных в HEX-виде
void dump_byte_array(byte *buffer, byte bufferSize)
{
for (byte i = 0; i < bufferSize; i++)
{
Serial.print(buffer[i] < 0x10 ? " 0" : " ");
Serial.print(buffer[i], HEX);
}
}

http://xn--18-6kcdusowgbt1a4b.xn--p1ai/df-player-mini-%D0%BF%D0%BE%D0%B4%D0%BA%D0%BB%D1%8E%D1%87%D0%B5%D0%BD%D0%B8%D0%B5-%D0%BA-%D0%B0%D1%80%D0%B4%D1%83%D0%B8%D0%BD%D0%BE/

https://pikabu.ru/story/arduino_i_mp3_modul_uchim_arduino_govorit_3939974

http://amperka.ru/product/df-player-mp3-module

https://www.dfrobot.com/wiki/index.php/DFPlayer_Mini_SKU:DFR0299

https://github.com/DFRobot/DFRobotDFPlayerMini

https://smartmodules.ru/dfplayer-mp3

http://rus-linux.net/MyLDP/consol/howto-format-usb.html

/*******************************************************************************
 * DFPlayer_Mini_Mp3, This library provides a quite complete function for      * 
 * DFPlayer mini mp3 module.                                                   *
 * www.github.com/dfrobot/DFPlayer_Mini_Mp3 (github as default source provider)*
 *  DFRobot-A great source for opensource hardware and robot.                  *
 *                                                                             *
 * This file is part of the DFplayer_Mini_Mp3 library.                         *
 *                                                                             *
 * DFPlayer_Mini_Mp3 is free software: you can redistribute it and/or          *
 * modify it under the terms of the GNU Lesser General Public License as       *
 * published by the Free Software Foundation, either version 3 of              *
 * the License, or any later version.                                          *
 *                                                                             *
 * DFPlayer_Mini_Mp3 is distributed in the hope that it will be useful,        *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of              *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               *
 * GNU Lesser General Public License for more details.                         *
 *                                                                             *
 * DFPlayer_Mini_Mp3 is distributed in the hope that it will be useful,        *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of              *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               *
 * GNU Lesser General Public License for more details.                         *
 *                                                                             *
 * You should have received a copy of the GNU Lesser General Public            *
 * License along with DFPlayer_Mini_Mp3. If not, see                           *
 * <http://www.gnu.org/licenses/>.                                             *
 *									       *
 ******************************************************************************/

/*
 *	Copyright:	DFRobot
 *	name:		DFPlayer_Mini_Mp3 sample code
 *	Author:		lisper <lisper.li@dfrobot.com>
 *	Date:		2014-05-30
 *	Description:	connect DFPlayer Mini by SoftwareSerial, this code is test on Uno
 *			Note: the mp3 files must put into mp3 folder in your tf card 
 */
#include <SoftwareSerial.h>
#include <DFPlayer_Mini_Mp3.h>

SoftwareSerial mySerial(10, 11); // RX, TX

//
void setup () {
	Serial.begin (9600);
	mySerial.begin (9600);
	mp3_set_serial (mySerial);	//set softwareSerial for DFPlayer-mini mp3 module 
	mp3_set_volume (15);
}


//
void loop () {        
	mp3_play (1);
	delay (6000);
	mp3_next ();
	delay (6000);
	mp3_prev ();

}

/*
   mp3_play ();		//start play
   mp3_play (5);	//play "mp3/0005.mp3"
   mp3_next ();		//play next 
   mp3_prev ();		//play previous
   mp3_set_volume (uint16_t volume);	//0~30
   mp3_set_EQ ();	//0~5
   mp3_pause ();
   mp3_stop ();
   void mp3_get_state (); 	//send get state command
   void mp3_get_volume (); 
   void mp3_get_u_sum (); 
   void mp3_get_tf_sum (); 
   void mp3_get_flash_sum (); 
   void mp3_get_tf_current (); 
   void mp3_get_u_current (); 
   void mp3_get_flash_current (); 
   void mp3_single_loop (boolean state);	//set single loop 
   void mp3_DAC (boolean state); 
   void mp3_random_play (); 
 */