STM32F769I-Discovery BSP User Manual: stm32f769i_discovery_audio.c File Reference

This file provides the Audio driver for the STM32F769I-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 STM32F769I-DISCOVERY (MB1225) Evaluation boards.
   + 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 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 STM32F769I-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_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 BSP_AUDIO_OUT_XXX_CallBack() and only their prototypes are declared in 
      the stm32f769i_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().

   + Call the function BSP_AUDIO_IN_Init(
                                    AudioFreq: Audio frequency in Hz (8000, 16000, 22500, 32000...)
                                                  this parameter is relative to the audio file/stream type.
                                    BitRes: Bit resolution fixed to 16bit
                                    ChnlNbr: Number of channel to be configured for the DFSDM peripheral
                                   )
      This function configures all the hardware required for the audio in application (DFSDM filters and channels, 
      Clock source for DFSDM periphiral, GPIOs, DMA and interrupt if needed). 
      This function returns AUDIO_OK if configuration is OK.If the returned value is different from AUDIO_OK then
      the configuration should be wrong.
      Note: On STM32F769I-DISCOVERY, four DFSDM Channel/Filters are configured and their DMA streams are configured
            in CIRCULAR mode.
   + Call the function BSP_AUDIO_IN_AllocScratch(
                                        pScratch: pointer to scratch tables
                                        size: size of scratch buffer)
     This function must be called before BSP_AUDIO_IN_RECORD() to allocate buffer scratch for each DFSDM channel
     and its size.
     Note: These buffers scratch are used as intermidiate buffers to collect data within final record buffer.
           size is the total size of the four buffers scratch; If size is 512 then the size of each is 128.
           This function must be called after BSP_AUDIO_IN_Init()
   + Call the function BSP_AUDIO_IN_RECORD(
                                  pBuf: pointer to the recorded audio data file address
                                  Size: size of the buffer to be written in Bytes
                                 )
      to start recording from microphones.

   + Call the function BSP_AUDIO_IN_Pause() to pause recording   
   + Call the function BSP_AUDIO_IN_Resume() to recording playing.
       Note. After calling BSP_AUDIO_IN_Pause() function for pause, only BSP_AUDIO_IN_Resume() should be called
          for resume (it is not allowed to call BSP_AUDIO_IN_RECORD() in this case).
   + Call the function BSP_AUDIO_IN_Stop() to stop recording 
   + For each mode, you may need to implement the relative callback functions into your code.
      The Callback functions are named BSP_AUDIO_IN_XXX_CallBack() and only their prototypes are declared in 
      the stm32f769i_discovery_audio.h file. (refer to the example for more details on the callbacks implementations)

  Driver architecture:
  --------------------
   + This driver provides the High Audio Layer: consists of the function API exported in the stm32f769i_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 stm32f769i_discovery_audio.c file (DFSDMx_Init(), DFSDMx_DeInit(), SAIx_Init() and SAIx_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 stm32f769i_discovery_audio.c.