I present this new Arduino project: A full MP3 player based on Arduino.
As you can see in the photo, the idea was to build a standalone player, in the style of antique radios or ‘tapes’, in the age of Iphones ….
The player uses a small module based on the VS1002d chip (now discontinued, but who had a drawer). The module in question I bought at Futurlec . Currently you can get similar modules on ebay for a bit more than 10$, although the chip is the VS1003 o VS1053. You can also use a SparkFun MP3 shield, but significantly more expensive (this shield already includes an SD slot).
The three chips are quite compatible in terms of programming, and indeed almost all initialization the I have taken from the library to the SparkFun MP3 Shield 
Both the SD as the MP3 module are connected to the Arduino using the SPI bus. The LCD is connected in 4 bits mode to save Arduino pins.
This is a table with the connections between Arduino and the other components. In parentheses, the name of the individual connections on modules (and the pin in the SD card).
This is a table with the connections between Arduino and the other components. In parentheses, the name of the individual connections on modules (and the pin in the SD card).
| PIN Arduino | MP3 Module | SD Card | LCD | Buttons |
| 0 | — | — | — | Forward |
| 1 | — | — | — | Back |
| 2 | DREQ | — | — | — |
| 3 | — | — | RS | — |
| 4 | — | — | ENABLE | — |
| 5 | (RESET) | — | — | — |
| 6 | CS (XCS) | — | — | — |
| 7 | DCS (BSYNC) | — | — | — |
| 8 | — | — | — | Encoder A |
| 9 | — | CS (CD/DAT3-1) | — | — |
| 10 | — | — | — | Encoder B |
| 11 | MOSI (SI) | MOSI (CMD-2) | — | — |
| 12 | MISO (SO) | MISO (DATO-7) | — | — |
| 13 | CLK (SCLK) | CLK (5) | — | — |
| A0 | — | — | D4 | — |
| A1 | — | — | D5 | — |
| A2 | — | — | D6 | — |
| A3 | — | — | D7 | — |
| A4 | — | — | — | — |
| A5 | — | — | — | — |
Read more: Arduino MP3 Player