PJRC Kit:

 

The PJRC kit is a 5.75 x 4.0 inch board with 4 corner mounting holes.  The board features an Atmel 82C55 chip, that provides 24 I/O lines, in addition to the 8 lines from the 8051's port #1, and the 8051's bus lines.  The firmware code is written in Atmel 8051 assembly due to limited address memory.  The board also contains 8 x 128 K of onboard ROM that is used to store the firmware.  It uses a Xilinx Spartan XL Field Programmable Gate Array (FPGA).  This kit is outfitted with both standard 40 pin IDE and 44 pin laptop connectors. 

 

Figure 1 PJRC MP3 Player Kit

 

Also, included is a 72-pin SIMM slot to provide additional buffer storage for MP3 data.  It can support 4, 8, 16, and 32 MB SIMMS.  In order to deliver high quality audio, this player is equipped with a 24-bit CS4334 Digital to Analog Converter (DAC).  To compliment this DAC, the board is built with a SGS Thompson STA013 MP3 decoder chip capable of supporting high quality MP3 bit rates such as 256 and 320 kbps.  Output is available via a headphone or RCA jacks.  Six buttons are incorporated on the board to control the player.  These buttons are next, play/pause, previous, random, volume up and volume down.  The system is capable of being powered in two ways.  First, it has a DC power jack that accepts voltage between 9 and 15 volts DC.  Second, it contains a 2-pin header that allows unregulated voltage between 4.5 and 6 volts.  These two power sources give it the flexibility to be powered by 4 AAA batteries or by an AC adapter connected to a car's electrical system [1].

 

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