AN3997

Application overview

Doc ID 022390 Rev 1

5/15

The main STM32 modules used by this application are:

●

USB peripheral: configured in Host mode. Mass Storage Class (MSC) is implemented

to transmit and receive audio data from/to USB key.

●

I2S peripheral: configured in Master Transmitter mode and used to transmit audio data

to the external audio codec (DAC). It is also used as a Master Receiver as an input

clock for the MEMS microphone.

●

DMA: is used to transmit data from the buffers to the I2S peripheral. This significantly

reduces the CPU load.

●

I2C peripheral: is used to control several external devices like the audio Codec and to

obtain data from this device.

●

SPI peripheral: used to control the MEMS accelerometer.

●

User button: is used to monitor the applications (playback or record).

Figure 2.

Audio playback and record modules

Note:

This application note is based on the STM32 USB On-The-Go (OTG) host and device

library. For more details about the USB Host stack and a mass storage demonstration,

please refer to the “STM32F105/7, STM32F2xx and STM32F4xx USB On-The-Go host and

device library” user manual (UM1021).

MS19887V1

I2C

Buttons

DMA

I2S

I2S

Internal

Flash

I/Os

USB host

Codec

(DAC)

STM32