I started to modify ARM stm32f7 demo audio recorder / playback application.

I'm going to connect TDM8 channels to the SAI on the ARM demo board.

The demo code is horrible for me. its a forest of board support packages BSP's and HAL's. I'm sure in a way its over complicating the basic idea that the SAI stream will be copied using DMA to the circular buffer. then when the buffer is half full the data is written to the USB stick ?! 

I'm thinking there does't need to be any timing as the data is just dumped onto the stick as a file as it comes in. I'm hoping there is a way to append data to the file on the stick rather than determining the audio record time as in the demo!

/*------------------------------------------------------------------------------
                          USER SAI defines parameters
 -----------------------------------------------------------------------------*/
/** CODEC_AudioFrame_SLOT_TDMMode In W8994 codec the Audio frame contains 4 slots : TDM Mode
  * TDM format :
  * +------------------|------------------|--------------------|-------------------+ 
  * | CODEC_SLOT0 Left | CODEC_SLOT1 Left | CODEC_SLOT0 Right  | CODEC_SLOT1 Right |
  * +------------------------------------------------------------------------------+
  */
/* To have 2 separate audio stream in Both headphone and speaker the 4 slot must be activated */
#define CODEC_AUDIOFRAME_SLOT_0123                   SAI_SLOTACTIVE_0 | SAI_SLOTACTIVE_1 | SAI_SLOTACTIVE_2 | SAI_SLOTACTIVE_3
/* To have an audio stream in headphone only SAI Slot 0 and Slot 2 must be activated */ 
#define CODEC_AUDIOFRAME_SLOT_02                     SAI_SLOTACTIVE_0 | SAI_SLOTACTIVE_2 
/* To have an audio stream in speaker only SAI Slot 1 and Slot 3 must be activated */ 
#define CODEC_AUDIOFRAME_SLOT_13                     SAI_SLOTACTIVE_1 | SAI_SLOTACTIVE_3

                                                       
/////////    ben tries to add arduino header SAI1_Block_B , no idea if this will work !
/////////    arduino header example I found used same defines as the onboard DAC

//configure SAI1 for Arduino header

#define AUDIO_OUT_SAIx                           SAI1_Block_A
#define AUDIO_OUT_SAIx_CLK_ENABLE()              __HAL_RCC_SAI1_CLK_ENABLE()
#define AUDIO_OUT_SAIx_CLK_DISABLE()             __HAL_RCC_SAI1_CLK_DISABLE()
#define AUDIO_OUT_SAIx_AF                        GPIO_AF6_SAI1
#define AUDIO_OUT_SAIx_MCLK_ENABLE()             __HAL_RCC_GPIOF_CLK_ENABLE()
#define AUDIO_OUT_SAIx_MCLK_GPIO_PORT            GPIOF
#define AUDIO_OUT_SAIx_MCLK_PIN                  GPIO_PIN_7 //PF7  MCLK
#define AUDIO_OUT_SAIx_SD_FS_CLK_ENABLE()        __HAL_RCC_GPIOF_CLK_ENABLE()
#define AUDIO_OUT_SAIx_SD_FS_SCK_GPIO_PORT       GPIOF
#define AUDIO_OUT_SAIx_FS_PIN                    GPIO_PIN_9 //  PF9  LRCK
#define AUDIO_OUT_SAIx_SCK_PIN                   GPIO_PIN_8  // PF8  BCK
#define AUDIO_OUT_SAIx_SD_PIN                    GPIO_PIN_6  // PF6  DATA

/* SAI DMA Stream definitions */
#define AUDIO_OUT_SAIx_DMAx_CLK_ENABLE()         __HAL_RCC_DMA2_CLK_ENABLE()
#define AUDIO_OUT_SAIx_DMAx_STREAM               DMA2_Stream1
#define AUDIO_OUT_SAIx_DMAx_CHANNEL              DMA_CHANNEL_0
#define AUDIO_OUT_SAIx_DMAx_IRQ                  DMA2_Stream1_IRQn
#define AUDIO_OUT_SAIx_DMAx_PERIPH_DATA_SIZE     DMA_PDATAALIGN_HALFWORD
#define AUDIO_OUT_SAIx_DMAx_MEM_DATA_SIZE        DMA_MDATAALIGN_HALFWORD
#define DMA_MAX_SZE                              0xFFFF
   
#define AUDIO_OUT_SAIx_DMAx_IRQHandler           DMA2_Stream1_IRQHandler

/* Select the interrupt preemption priority and subpriority for the DMA interrupt */
#define AUDIO_OUT_IRQ_PREPRIO                    ((uint32_t)0x0E) 


///////  end ben tried to add SAI1_Block_A

/*------------------------------------------------------------------------------
                        AUDIO IN CONFIGURATION
------------------------------------------------------------------------------*/

/* SAI peripheral configuration defines */
#define AUDIO_IN_SAIx                           SAI1_Block_B
#define AUDIO_IN_SAIx_CLK_ENABLE()              __HAL_RCC_SAI1_CLK_ENABLE()
#define AUDIO_IN_SAIx_CLK_DISABLE()             __HAL_RCC_SAI1_CLK_DISABLE()
#define AUDIO_IN_SAIx_AF                        GPIO_AF6_SAI1
#define AUDIO_IN_SAIx_SD_ENABLE()               __HAL_RCC_GPIOE_CLK_ENABLE()
#define AUDIO_IN_SAIx_SD_GPIO_PORT              GPIOE
#define AUDIO_IN_SAIx_SD_PIN                    GPIO_PIN_3
#define AUDIO_IN_INT_GPIO_ENABLE()               __HAL_RCC_GPIOJ_CLK_ENABLE()
#define AUDIO_IN_INT_GPIO_PORT                   GPIOJ
#define AUDIO_IN_INT_GPIO_PIN                    GPIO_PIN_12
#define AUDIO_IN_INT_IRQ                         EXTI15_10_IRQn

/* SAI DMA Stream definitions */
#define AUDIO_IN_SAIx_DMAx_CLK_ENABLE()         __HAL_RCC_DMA2_CLK_ENABLE()
#define AUDIO_IN_SAIx_DMAx_STREAM               DMA2_Stream4
#define AUDIO_IN_SAIx_DMAx_CHANNEL              DMA_CHANNEL_1
#define AUDIO_IN_SAIx_DMAx_IRQ                  DMA2_Stream4_IRQn
#define AUDIO_INx_DMAx_STREAM_IRQHandler        DMA2_Stream4_IRQHandler
#define AUDIO_IN_SAIx_DMAx_PERIPH_DATA_SIZE     DMA_PDATAALIGN_WORD
#define AUDIO_IN_SAIx_DMAx_MEM_DATA_SIZE        DMA_MDATAALIGN_WORD
#define DMA_MAX_SZE                              0xFFFF


/* Select the interrupt preemption priority and subpriority for the DMA interrupt */
#define AUDIO_IN_IRQ_PREPRIO                ((uint32_t)0x0F)

// end SAI   AUDIO IN CONFIGURATION



/*------------------------------------------------------------------------------
             CONFIGURATION: Audio Driver Configuration parameters
------------------------------------------------------------------------------*/

#define AUDIODATA_SIZE                      4   /* 16-bits audio data size */

/* Audio status definition */     
#define AUDIO_OK                            ((uint8_t)0)
#define AUDIO_ERROR                         ((uint8_t)1)
#define AUDIO_TIMEOUT                       ((uint8_t)2)

/* Audio In default settings */
#define DEFAULT_AUDIO_IN_FREQ               BSP_AUDIO_FREQUENCY_48K
#define DEFAULT_AUDIO_IN_BIT_RESOLUTION     ((uint8_t)24) // can ring buffer load 24bit ? or 32bit ?
#define DEFAULT_AUDIO_IN_CHANNEL_NBR        ((uint8_t)2) // change to channel count
#define DEFAULT_AUDIO_IN_VOLUME             ((uint16_t)64)

/*------------------------------------------------------------------------------
                            OUTPUT DEVICES definition
------------------------------------------------------------------------------*/
/* Alias on existing output devices to adapt for 2 headphones output */
#define OUTPUT_DEVICE_HEADPHONE1 OUTPUT_DEVICE_HEADPHONE
#define OUTPUT_DEVICE_HEADPHONE2 OUTPUT_DEVICE_SPEAKER /* Headphone2 is connected to Speaker output of the wm8994 */

/*------------------------------------------------------------------------------
                           INPUT DEVICES definition
------------------------------------------------------------------------------*/
/* MP34DT01TR digital microphone on PCB top side */
#define INPUT_DEVICE_DIGITAL_MIC       ((uint16_t)0)
/* Analog microphone input from 3.5 audio jack connector */    
#define INPUT_DEVICE_ANALOG_MIC        INPUT_DEVICE_INPUT_LINE_1  

/**
  * @}
  */
   
/** @defgroup STM32F769I_DISCOVERY_AUDIO_Exported_Macros STM32F769I_DISCOVERY_AUDIO Exported Macros
  * @{
  */
#define DMA_MAX(x)           (((x) <= DMA_MAX_SZE)? (x):DMA_MAX_SZE)
/**
  * @}
  */ 

/** @defgroup STM32F769I_DISCOVERY_AUDIO_OUT_Exported_Functions STM32F769I_DISCOVERY_AUDIO_OUT Exported Functions
  * @{
  */
uint8_t BSP_AUDIO_OUT_Init(uint16_t OutputDevice, uint8_t Volume, uint32_t AudioFreq);
void    BSP_AUDIO_OUT_DeInit(void);
uint8_t BSP_AUDIO_OUT_Play(uint16_t* pBuffer, uint32_t Size);
void    BSP_AUDIO_OUT_ChangeBuffer(uint16_t *pData, uint16_t Size);
uint8_t BSP_AUDIO_OUT_Pause(void);
uint8_t BSP_AUDIO_OUT_Resume(void);
uint8_t BSP_AUDIO_OUT_Stop(uint32_t Option);
uint8_t BSP_AUDIO_OUT_SetVolume(uint8_t Volume);
void    BSP_AUDIO_OUT_SetFrequency(uint32_t AudioFreq);
void    BSP_AUDIO_OUT_SetAudioFrameSlot(uint32_t AudioFrameSlot);
uint8_t BSP_AUDIO_OUT_SetMute(uint32_t Cmd);
uint8_t BSP_AUDIO_OUT_SetOutputMode(uint8_t Output);

/* User Callbacks: user has to implement these functions in his code if they are needed. */
/* This function is called when the requested data has been completely transferred.*/
void    BSP_AUDIO_OUT_TransferComplete_CallBack(void);

/* This function is called when half of the requested buffer has been transferred. */
void    BSP_AUDIO_OUT_HalfTransfer_CallBack(void);

/* This function is called when an Interrupt due to transfer error on or peripheral
   error occurs. */
void    BSP_AUDIO_OUT_Error_CallBack(void);

/* These function can be modified in case the current settings (e.g. DMA stream)
   need to be changed for specific application needs */
void  BSP_AUDIO_OUT_ClockConfig(SAI_HandleTypeDef *hsai, uint32_t AudioFreq, void *Params);
void  BSP_AUDIO_OUT_MspInit(SAI_HandleTypeDef *hsai, void *Params);
void  BSP_AUDIO_OUT_MspDeInit(SAI_HandleTypeDef *hsai, void *Params);

/**
  * @}
  */ 

/** @defgroup STM32F769I_DISCOVERY_AUDIO_IN_Exported_Functions STM32F769I_DISCOVERY_AUDIO_IN Exported Functions
  * @{
  */
uint8_t BSP_AUDIO_IN_Init(uint32_t AudioFreq, uint32_t BitRes, uint32_t ChnlNbr);
uint8_t BSP_AUDIO_IN_InitEx(uint16_t InputDevice, uint32_t AudioFreq, uint32_t BitRes, uint32_t ChnlNbr);
uint8_t BSP_AUDIO_IN_AllocScratch (int32_t *pScratch, uint32_t size);
uint8_t BSP_AUDIO_IN_GetChannelNumber(void);
void    BSP_AUDIO_IN_DeInit(void);
uint8_t BSP_AUDIO_IN_Record(uint16_t *pData, uint32_t Size);
uint8_t BSP_AUDIO_IN_Stop(void);
uint8_t BSP_AUDIO_IN_Pause(void);
uint8_t BSP_AUDIO_IN_Resume(void);

/* User Callbacks: user has to implement these functions in his code if they are needed. */
/* This function should be implemented by the user application.
   It is called into this driver when the current buffer is filled to prepare the next
   buffer pointer and its size. */
void    BSP_AUDIO_IN_TransferComplete_CallBack(void);
void    BSP_AUDIO_IN_HalfTransfer_CallBack(void);

/* This function is called when an Interrupt due to transfer error on or peripheral
   error occurs. */
void    BSP_AUDIO_IN_Error_CallBack(void);
     
/* These function can be modified in case the current settings (e.g. DMA stream)
   need to be changed for specific application needs */
void BSP_AUDIO_IN_ClockConfig(DFSDM_Filter_HandleTypeDef *hdfsdm_filter, uint32_t AudioFreq, void *Params);
void BSP_AUDIO_IN_MspInit(void);
void BSP_AUDIO_IN_MspDeInit(void);

/**
  * @}
  */ 

/**
  * @}
  */ 

/**
  * @}
  */

/**
  * @}
  */

#ifdef __cplusplus
}
#endif

#endif /* __STM32F769I_DISCOVERY_AUDIO_H */