Support sampling frequency (kHz):8 / 11.025 / 12 / 16 / 22.05 / 24 / 32 / 44.1 / 48
 Support file format:MP3/WAV
 Support Micro SD card, Micro SDHC Card
 30 class adjustable volume
 UART TTL serial control playback mode, baud rate is 9600bps
 Power supply can be 3.2 ~ 5.2VDC
 Size:43mm x 25mm

//code rearranged by Javier Muñoz 10/11/2016 ask me at javimusama@hotmail.com
#include <SoftwareSerial.h>

#define ARDUINO_RX 5//should connect to TX of the Serial MP3 Player module
#define ARDUINO_TX 6//connect to RX of the module
SoftwareSerial mySerial(ARDUINO_RX, ARDUINO_TX);//init the serial protocol, tell to myserial wich pins are TX and RX

////////////////////////////////////////////////////////////////////////////////////
//all the commands needed in the datasheet(http://geekmatic.in.ua/pdf/Catalex_MP3_board.pdf)
static int8_t Send_buf[8] = {0} ;//The MP3 player undestands orders in a 8 int string
                                 //0X7E FF 06 command 00 00 00 EF;(if command =01 next song order) 
#define NEXT_SONG 0X01 
#define PREV_SONG 0X02 

#define CMD_PLAY_W_INDEX 0X03 //DATA IS REQUIRED (number of song)

#define VOLUME_UP_ONE 0X04
#define VOLUME_DOWN_ONE 0X05
#define CMD_SET_VOLUME 0X06//DATA IS REQUIRED (number of volume from 0 up to 30(0x1E))
#define SET_DAC 0X17
#define CMD_PLAY_WITHVOLUME 0X22 //data is needed  0x7E 06 22 00 xx yy EF;(xx volume)(yy number of song)

#define CMD_SEL_DEV 0X09 //SELECT STORAGE DEVICE, DATA IS REQUIRED
                #define DEV_TF 0X02 //HELLO,IM THE DATA REQUIRED
                
#define SLEEP_MODE_START 0X0A
#define SLEEP_MODE_WAKEUP 0X0B

#define CMD_RESET 0X0C//CHIP RESET
#define CMD_PLAY 0X0D //RESUME PLAYBACK
#define CMD_PAUSE 0X0E //PLAYBACK IS PAUSED

#define CMD_PLAY_WITHFOLDER 0X0F//DATA IS NEEDED, 0x7E 06 0F 00 01 02 EF;(play the song with the directory \01\002xxxxxx.mp3

#define STOP_PLAY 0X16

#define PLAY_FOLDER 0X17// data is needed 0x7E 06 17 00 01 XX EF;(play the 01 folder)(value xx we dont care)

#define SET_CYCLEPLAY 0X19//data is needed 00 start; 01 close

#define SET_DAC 0X17//data is needed 00 start DAC OUTPUT;01 DAC no output
////////////////////////////////////////////////////////////////////////////////////


void setup()
{
  Serial.begin(9600);//Start our Serial coms for serial monitor in our pc
mySerial.begin(9600);//Start our Serial coms for THE MP3
delay(500);//Wait chip initialization is complete
   sendCommand(CMD_SEL_DEV, DEV_TF);//select the TF card  
delay(200);//wait for 200ms

}
void loop()
{
sendCommand(CMD_PLAY_WITHVOLUME, 0X0F01);//play the first song with volume 15 class
delay(1000000);//the programm will send the play option each 100 seconds to the catalex chip
}

void sendCommand(int8_t command, int16_t dat)
{
 delay(20);
 Send_buf[0] = 0x7e; //starting byte
 Send_buf[1] = 0xff; //version
 Send_buf[2] = 0x06; //the number of bytes of the command without starting byte and ending byte
 Send_buf[3] = command; //
 Send_buf[4] = 0x00;//0x00 = no feedback, 0x01 = feedback
 Send_buf[5] = (int8_t)(dat >> 8);//datah
 Send_buf[6] = (int8_t)(dat); //datal
 Send_buf[7] = 0xef; //ending byte
 for(uint8_t i=0; i<8; i++)//
 {
   mySerial.write(Send_buf[i]) ;//send bit to serial mp3
   Serial.print(Send_buf[i],HEX);//send bit to serial monitor in pc
 }
 Serial.println();
}