DocID024112 Rev 1

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AN4229

How to use the demonstration

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How to use the demonstration

3.1

Hardware configuration

Supported boards are: STM32F4DISCOVERY (referred as DISCOVERY board hereafter),

STM322xG-EVAL and STM324xG-EVAL (referred as EVAL boards hereafter).

EVAL boards settings for the "demonstration":

•

Connect a USB flash drive to the USB OTG FS connector (CN8).

•

Connect an SD card to the MSC connector (CN6), also jumper JP16 must be set to

position 1-2 (MSD) to be able to use SD card.

•

Connect a headset (headphone + microphone) to the audio jack connector (CN11).

EVAL boards settings for the simple examples (such as "Simple_G711"):

•

Connect a headset (headphone + microphone) to the audio jack connector (CN11).

DISCOVERY board settings:

•

Connect a USB flash drive to the USB OTG FS connector (CN5).

•

Connect a headphone to the audio jack connector (CN4); no external microphone is

needed as the MEMS integrated microphone (U9) is used.

3.2

Firmware configuration

All the settings that a typical user needs to adjust are regrouped into one single file:

Demonstration\inc\audio_app_conf.h.

For example PLAYLIST_DIRECTORY and RECORD_DIRECTORY permit to set the

directory paths where the player/recorder will read/write audio files. Note that "0:/"

corresponds to USB flash drive and "1:/" corresponds to SD card.

In addition to general audio settings, such as volume (DEFAULT_VOLUME) and sampling

frequency (SAMPLE_RATE_FREQ), all the codecs parameters can also be set into this file

(audio_app_conf.h). There is only one exception: the Speex mode selection (narrowband or

wideband) is set directly into the preprocessor defined symbols.

Users should take in consideration the following correspondence table (Table 7) when

setting Speex parameters:

Table 7. Speex encoded frame size

SPX_ENCODER_QUALITY

ENCODED_FRAME_SIZE

Narrowband

Wideband

110

15

215

20

320

25

420

32

528

42

628

52