AN2400

Audio player evaluation board concept

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2

Audio player evaluation board concept

2.1

Audio recording

A PC is used to prepare audio to be programmed onto the external serial Flash. The file

must contain audio data as well as some basic file management structure to allow the ST7

to pick the correct audio during playback.

The serial Flash is used to store the audio files in binary format. For this purpose, it is

necessary to have the audio files in .wav format which allows them to be converted to a .bin

file to be programmed into the serial Flash.

For conversion to binary, the .wav files should have an 8 kHz sampling frequency and 8-bit

quantization format. These files are input into the provided WAV Converter utility to generate

a single .bin file.

Figure 3.

Sound recording flow

Once this process is completed, the board is ready to play customized sounds provided by

the user.

A sound is selected using the Index push-button, and then heard by pressing the Play

button.

WAV

BIN

011011011

001010101

Recording process: Can be done on a standard PC, in a recording studio, or just some existing audio samples

Original Sound

Sampling

Quantifying

PC Processing: Convert the .WAV files into a propriety binary file used to reprogram the onboard serial Flash

WAV

WAV

WAV File Storage

Conversion to Binary File

Burn binary file to M25P

Serial Flash Memory

Standard

8kHz/8-bit

.WAV files