Altera DE2-115 User Manual download pdf (Page 94)

Main

Nios HAL

System

Call

SEG7 I2C Audio

WAVE Lib

FAT16/FAT32

SD 4-bit Mode

Receiver

Figure 6-14 Software Stack of the SD music player demonstration

The audio chip should be configured before sending audio signal to the audio chip. The main

program uses I2C protocol to configure the audio chip working in master mode; the audio output

interface working in I2S 16-bits per channel and with sampling rate according to the wave file

contents. In audio playing loop, the main program reads 512-byte audio data from the SD Card, and

then writes the data to DAC FIFO in the Audio Controller. Before writing the data to the FIFO, the

program will verify if the FIFO is full. The design also mixes the audio signal from the

microphone-in and line-in for the Karaoke-style effects by enabling the BYPASS and SITETONE

functions in the audio chip.

Finally, users can obtain the status of the SD music player from the 16x2 LCD module, the

7-segment display, and the LEDs. The top and bottom row of the LCD module will display the file

name of the music that is played on the DE2-115 board and the value of music volume, respectively.

The 7-segment displays will show the elapsed time of the playing music file. The LED will indicate

the audio signal strength.

 Demonstration Setup, File Locations, and Instructions

• Project directory: DE2_115_SD_Card_Audio_Player

• Bit stream used: DE2_115_SD_Card_Audio_Player.sof

• Nios II Workspace: DE2_115_SD_Card_Audio_Player\Software

• Format your SD Card into FAT16/FAT32 format

• Place the wave files to the root directory of the SD Card. The provided wave files must

have a sample rate of either 96K, 48K, 44.1K, 32K, or 8K. In addition, the wave files must

be stereo and 16 bits per channel.

• Load the bitstream into the FPGA on the DE2-115 board(note*1)

• Run the Nios II Software under the workspace

DE2_115_SD_Card_Audio_Player\Software(note*1)

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Altera DE2-115 User Manual Page 94