User manual

DE2 User Manual
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Figure 5.10. The setup for the Ethernet demonstration.
5.7 SD Card Music Player
Many commercial media/audio players use a large external storage device, such as an SD card or
CF card, to store music or video files. Such players may also include high-quality DAC devices so
that good audio quality is produced. The DE2 board provides the hardware and software needed for
SD card access and professional audio performance so that it is possible to design advanced
multimedia products using the DE2 board.
In this demonstration we show how to implement an SD Card Music Player on the DE2 board, in
which the music files are stored in an SD card and the board can play the music files via its
CD-quality audio DAC circuits. We use the Nios II processor to read the music data stored in the
SD Card and use the Wolfson WM8731 audio CODEC to play the music.
The audio CODEC is configured in the slave mode, where external circuitry must provide the
ADC/DAC serial bit clock (BCK) and left/right channel clock (LRCK) to the audio CODEC. As
shown in Figure 5.11, we provide an Audio DAC Controller to achieve the clock generation and the
data flow control. The Audio DAC Controller is integrated into the Avalon bus architecture, so that
the Nios II processor can control the application.