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AN4229

FAQ

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5

FAQ

This section gathers some of the most frequent questions vocoders package users may

ask. It gives some solutions and tips.

Table 9. FAQ

No.

Question

Answer/Solution

1

How to select media storage

(USB flash drive or SD card)?

In file “audio_app_conf.h”, set PLAYLIST_DIRECTORY

and/or RECORD_DIRECTORY to “0:/” to select USB flash

drive and “1:/” to select SD card. By default these two

defines are set to “0:/USER”.

2

How to configure Codecs

parameters?

Almost all codec parameters can be set into

“audio_app_conf.h” file. See Section 3.2

for other alternatives.

3

Is there any parameter to

configure when implementing

the application in EVAL boards

or DISCOVERY board?

All necessary configurations are already done and

managed by these three defines: USE_STM322xG_EVAL,

USE_STM324xG_EVAL and

USE_STM3F4XX_DISCOVERY.

As reference, main differences are:

– HSE_VALUE (equal to 8 MHz on the DISCOVERY board

and 25 MHz on the EVAL board)

– LCD support (only on EVAL)

– SD card support (only on EVAL)

– MEMS accelerometer support (only on DISCOVERY

board)

– USB power switch port configuration

(HOST_POWERSW_PORT_RCC,

HOST_POWERSW_PORT and

HOST_POWERSW_VBUS)

4

How to add a new codec?

To allow the application to support new codec, the user

should:

– Add codec routines under “Codecs/”

– Add the codec functions (callbacks) layer regrouped into

a new file called “xxxprocess.c” (under Common/). User

can take “wavprocess.c” as reference.

– Update file “Common/stm32_audio_decoders.c” to

support new function associations.

Normally, the other layers (player, recorder, audio_in and

audio_out Interfaces) do not have to be modified.

5

How to disable LCD display on

EVAL board?

Un-define (comment) LCD_ENABLE, into

“audio_app_conf.h”.