STM32746G-Discovery BSP User Manual: stm32746g_discovery_audio.c File Reference

This file provides the Audio driver for the STM32746G-Discovery board.

Author:

MCD Application Team

Version:

V2.0.0

Date:

30-December-2016

    How To use this driver:
    -----------------------
       + This driver supports STM32F7xx devices on STM32746G-Discovery (MB1191) board.
       + Call the function BSP_AUDIO_OUT_Init(
                                        OutputDevice: physical output mode (OUTPUT_DEVICE_SPEAKER, 
                                                      OUTPUT_DEVICE_HEADPHONE or OUTPUT_DEVICE_BOTH)
                                        Volume      : Initial volume to be set (0 is min (mute), 100 is max (100%)
                                        AudioFreq   : Audio frequency in Hz (8000, 16000, 22500, 32000...)
                                                      this parameter is relative to the audio file/stream type.
                                       )
          This function configures all the hardware required for the audio application (codec, I2C, SAI, 
          GPIOs, DMA and interrupt if needed). This function returns AUDIO_OK if configuration is OK.
          If the returned value is different from AUDIO_OK or the function is stuck then the communication with
          the codec or the MFX has failed (try to un-plug the power or reset device in this case).
          - OUTPUT_DEVICE_SPEAKER  : only speaker will be set as output for the audio stream.
          - OUTPUT_DEVICE_HEADPHONE: only headphones will be set as output for the audio stream.
          - OUTPUT_DEVICE_BOTH     : both Speaker and Headphone are used as outputs for the audio stream
                                     at the same time.
          Note. On STM32746G-Discovery SAI_DMA is configured in CIRCULAR mode. Due to this the application
            does NOT need to call BSP_AUDIO_OUT_ChangeBuffer() to assure streaming.
       + Call the function BSP_DISCOVERY_AUDIO_OUT_Play(
                                      pBuffer: pointer to the audio data file address
                                      Size   : size of the buffer to be sent in Bytes
                                     )
          to start playing (for the first time) from the audio file/stream.
       + Call the function BSP_AUDIO_OUT_Pause() to pause playing   
       + Call the function BSP_AUDIO_OUT_Resume() to resume playing.
           Note. After calling BSP_AUDIO_OUT_Pause() function for pause, only BSP_AUDIO_OUT_Resume() should be called
              for resume (it is not allowed to call BSP_AUDIO_OUT_Play() in this case).
           Note. This function should be called only when the audio file is played or paused (not stopped).
       + For each mode, you may need to implement the relative callback functions into your code.
          The Callback functions are named AUDIO_OUT_XXX_CallBack() and only their prototypes are declared in 
          the stm32746g_discovery_audio.h file. (refer to the example for more details on the callbacks implementations)
       + To Stop playing, to modify the volume level, the frequency, the audio frame slot, 
          the device output mode the mute or the stop, use the functions: BSP_AUDIO_OUT_SetVolume(), 
          AUDIO_OUT_SetFrequency(), BSP_AUDIO_OUT_SetAudioFrameSlot(), BSP_AUDIO_OUT_SetOutputMode(),
          BSP_AUDIO_OUT_SetMute() and BSP_AUDIO_OUT_Stop().
       + The driver API and the callback functions are at the end of the stm32746g_discovery_audio.h file.
     
    Driver architecture:
    --------------------
       + This driver provides the High Audio Layer: consists of the function API exported in the stm32746g_discovery_audio.h file
         (BSP_AUDIO_OUT_Init(), BSP_AUDIO_OUT_Play() ...)
       + This driver provide also the Media Access Layer (MAL): which consists of functions allowing to access the media containing/
         providing the audio file/stream. These functions are also included as local functions into
         the stm32746g_discovery_audio_codec.c file (SAIx_Out_Init() and SAIx_Out_DeInit(), SAIx_In_Init() and SAIx_In_DeInit())
    
    Known Limitations:
    ------------------
       1- If the TDM Format used to play in parallel 2 audio Stream (the first Stream is configured in codec SLOT0 and second 
          Stream in SLOT1) the Pause/Resume, volume and mute feature will control the both streams.
       2- Parsing of audio file is not implemented (in order to determine audio file properties: Mono/Stereo, Data size, 
          File size, Audio Frequency, Audio Data header size ...). The configuration is fixed for the given audio file.
       3- Supports only Stereo audio streaming.
       4- Supports only 16-bits audio data size.
  

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Definition in file stm32746g_discovery_audio.c.