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.
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.
We adapted the design for our circuit from the schematic
given on the PJRC
website. The schematic for our circuit can be viewed here.
Since the STA013 and the CS4334 were surface-mount chips, both chips
required DIP adapters to connect to a breadboard. We used the Aries
Electronics 32-650000-10 and the Capital Advanced Technologies 9082
for the STA013 and CS4334, respectively.
In order to improve the quality of the output of
the DAC (i.e., eliminate noise, etc.), both the left and right outputs
were filtered using a band-pass filter. In addition, an inductor
was placed in series with the 5 volt supply rail for the DAC in
order to eliminate noise due to other circuitry.