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MP3 Player Using Atmel Mega103L




Introduction

Using MPEG Layer-3 compression, 40 MByte audio files have been compressed to approximately 3.5 MBytes. With the wide availability of MP3 files via the Internet, portable MP3 players have become increasingly popular. MP3 players are currently available that utilize either Compact Discs, SmartMedia, Compact Flash, or a hard-drive as their storage medium.

MP3 Player Using Atmel Mega103L

MP3 Player Using Atmel Mega103L

Our interest in MP3 technology led us to design a circuit that would convert an MP3 file into an audio signal for our final project. The circuit utilizes an MP3 decoder chip to convert an MP3 file into a digital signal. The resulting digital signal is then converted to an analog audio signal via a Digital-to-Analog Converter (DAC). An 8-bit Microcontroller controls the flow of data to the MP3 decoder chip.

Since we finished the MP3 decoding circuit ahead of schedule, we decided to additionally implement a hard-drive interface to store the MP3 files. Once again, an 8-bit Microcontroller controlled all data transfers to and from the hard-drive. Due to time limitations, we were not able to finish the software drivers for this circuit.

Hardware

MP3 Decoder Circuity:

For our original design, we intended to use the VS1001 MP3 decoder chip. Due to the amount of time required to obtain the VS1001 MP3 decoder chip, we decided to change our design to use the STA013 MP3 decoder chip clocked at 14.7456 MHz. We also chose to use the CS4334 24-bit DAC, as the STA013 is capable of generating all control signals for it.

MP3 Player

As the STA013 is a 3 Volt chip, we chose to use the Atmel Mega103L Microcontroller which is also a 3 Volt chip. This eliminated the need for any level shifting of signals between the STA013 and the Atmel Mega103L. The additional flash memory (128K in total) on the Atmel Mega103L also allowed us to store a short MP3 clip on the MCU in order to test the Atmel Mega103L/STA013 interface.

 
Parts List:

  • STA013 MP3 Decoder Chip
  • Aries Electronics 32-650000-10 Dip Adaptor
  • 14.7456 MHz Crystal
  • CS4334 24-bit Digital-to-Analog Converter
  • Advanced Technologies 9082 Surf Board
  • Atmel Mega103L
  • STK300 Development Board
  • Bench Power Supply
  • Amplified Computer Speakers
  • 1/8″ Stereo Jack
  • 340 MByte Hard-Drive
  • IDE Cable
  • 2 Breadboards

 

  • 16 x 270 Ohm Resistors
  • 16 x 4.7 K Ohm Resistors
  • 2 x 4.7 Ohm Resistors
  • 2 x 560 Ohm Resistors
  • 1 x 1 K Ohm Resistor
  • 1 x 1 M Ohm Resistor
  • 1 x 100 µH Inductor
  • 6 x 0.1 µF Capacitors
  • 2 x 34 pF Capacitors
  • 1 x 10 µF Capacitor
  • 2 x 3.3 µF Capacitors
  • 2 x 3.3 nF Capacitors
  • 1 x 470 pF Capacitor
  • 1 x 4.7 nF Capacitor
  • Wire

 

For more detail: EE 476 Final Project: MP3 Player

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