STM32CubeF3

@verbatim
******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
* @file I2S/I2S_Audio/readme.txt
* @author MCD Application Team
* @brief Description of the I2S Audio Example.
******************************************************************************
* @attention
*
* Copyright (c) 2016 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
@endverbatim

@par Example Description

Basic implementation of audio features. This example allows playing an audio
file with an external codec on the STM32373C-EVAL board through the I2S
peripheral using DMA transfer.

In this example the I2S input clock, provided by a dedicated PLL (PLLI2S), is
configured to have an audio sampling frequency at 8 KHz with Master clock enabled.

This example uses an audio codec driver which consists of two independent layers:
- Codec Hardware layer: which controls and communicates with the audio codec
(CS43L22) implemented on the evaluation board.
- The high layer: which implements overall control and interfacing API allowing
to perform basic audio operations (Init, Play, Pause, Resume, Stop, Volume
control and audio file pointer management)

In this example the audio file is stored in the internal flash memory (Mono,
16-bit, 8 KHz). The analog output device is automatically detected when the Headphone
is plugged/unplugged in/from the audio jack of the evaluation board. The example also
manages information display and control interface through push buttons:
- Key : Pause/Resume
- Joystick up : Volume UP
- Joystick down: Volume DOWN

This example plays the audio file stored in internal flash memory and replays it
when it reaches end of file. But it can be tailored to used different media storage
devices (SDCard (through SDIO), external Memory (through FSMC) ...) or to play
in streaming mode (ie. from USB port in device or host mode). In this case, Circular
DMA mode should be preferred (by enabling the define DMA_CIRCULAR in
I2Sx_MspInit() API of stm32373c_eval_audio.c file).

List of Known Limitations and more detailed user notes are provided in file
stm32373c_eval_audio.c (under Drivers\BSP\STM32373C_EVAL)

The provided sample Audio file (stored in internal Flash memory) is extracted from:
- Title: Partita E major, Gavotte en rondeau
- Artist/Composer: J.-S. Bach

@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.

@note The application need to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.

@par Directory contents

- I2S/I2S_Audio/Inc/stm32f3xx_hal_conf.h HAL configuration file
- I2S/I2S_Audio/Inc/stm32f3xx_it.h Interrupt handlers header file
- I2S/I2S_Audio/Inc/main.h Header for main.c module
- I2S/I2S_Audio/Src/stm32f3xx_it.c Interrupt handlers
- I2S/I2S_Audio/Src/main.c Main program
- I2S/I2S_Audio/Src/system_stm32f3xx.c STM32F3xx system source file
- I2S/I2S_Audio/Src/stm32f3xx_hal_msp.c HAL MSP file
- I2S/I2S_Audio/Src/audio_sample.c Audio Sample file (in tab format)

@par Hardware and Software environment
- This example runs on STM32F373xx devices.
- This example has been tested with STMicroelectronics STM32373C-EVAL RevB
evaluation boards and can be easily tailored to any other supported device
and development board.

- STM32373C-EVAL Set-up
- Jumper JP4 and JP5 need to be set in I2C2 position.

@par How to use it ?

In order to make the program work, you must do the following :
- Open your preferred toolchain
- Rebuild all files and load your image into target memory
- Run the example
- Connect a headphone to the audio jack connector (CN11).