Embedded MP3 Player and Recorder

Contents:

The Embedded MP3 Player and Recorder is a player and recorder system that supports various formats of audio compression and decompression in real time, including the popular MP3 and Ogg Vorbis format. The device is designed as a SIL module. It can be used as a module in a generic printed circuit board both as a standalone component in a breadboard. The system is manageable by: UART, USB, I²C bus, I/O in bit banging, buttons or combination of previous solutions. The Embedded MP3 requires only a single power supply that can be either 3.3V or 5V @ 1 W.

Player in 3D rendering with Altium

 

The MP3 Player & Recorder has the following features:

  • textual (CLI, SCC, I2C) or digital (IO, USB, UART), activation commands;
  • microSD slot, up to 32 GByte (FAT12, FAT16 and FAT32 supported);
  • USB 2.0 Client connection (simultaneously Mass Storage and Serial Emulator);
  • File-based system configurations (auto generated with default properties into virgin memories);
  • 32 bit MCU with VS_DSP coprocessor, real time hardware MP3 encoder and decoder;
  • Single side components placement and soldering process for reduce thickness (less than 3 mm);
  • Standard 2.54 mm vertical pin header strip (only 15 pins);
  • Automatic selection of 5 V or 3.3 V power supply;
  • USB or UART serial port: Command Line Interpreter (CLI) or Single Character Commands (SCC);
  • CLI: Unix like shell interpreter;
  • I2C and Bit banging IO simple interaction;
  • Upgradeable firmware by user.

 

 

The Embedded MP3 Player and Recorder has a 32 bit core that runs at 50 Mhz with only 1 Watt of power consumption. The real time hardware encoder and decoder is based on VS1063 chip of the VLSI Solution. The VS1063 IC can encode a multitude of audio formats, from MP3 and Ogg Vorbis to G.711 u-law, G.711 A-law, G.722 and 16-bit PCM. The proprietary MP3 encoder and Ogg Vorbis encoder have been carefully tuned for highest possible audio fidelity for high-quality audio streaming or recording. VS1063, also, can play back MP2, MP3, WMA, OGG, LC-AAC, HE-AAC, FLAC, IMA, G.711 u-law, G.711 a-law, G.722 and WAV PCM formats, making it very suitable for hi-fi audio playback.

 

All the I/O connections are on the single-inline connector (1x15 pin with a pitch of 2.54mm). The pin-out description is reported in the following table:

#  Name  Primary description  Alternative description
1  Vdd  Power supply 5 V or 3.3 V (The GPIO are always at 3.3 V)  
2  Gnd  Ground reference  
3  MCLR  Hard reset  
4  SCL/IO0  I²C clock   General purpose I/O number 0
5  SDA/IO1  I²C data  General purpose I/O number 1
6  AN0/IO2  Analog input number 0  General purpose I/O number 2
7  AN1/IO3  Analog input number 1  General purpose I/O number 3
8  RX/IO4  UART native receiver  General purpose I/O number 4
9  TX/IO5  UART native transmitter  General purpose I/O number 5
10  USB_P/IO6  USB Data +  General purpose I/O number 6
11  USB_N/IO7  USB Data -  General purpose I/O number 7
12  Rout  Line-Out, right channel  
13  Lout  Line-Out, left channel  
14  Rin  Line-In, right channel  
15  Lin  Line-In, left channel  

To control the device via I²C you need to add 2,2 kohm pull-up resistors. All the I/O are TTL at 3,3 V and they are not 5V tolerant. To adapt the I/O of the Embedded MP3 at 3.3 V in a bidirectional connection with a device at 5 V you can use a mosfet for each channel as a Logic Level Converter. The following picture shows how use it.

3.3 V to 5 V conversion and viceversa

 


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