CubeMX Initialization for SAI with MEMS microphone input - STM32F746g-disco
Hello,
I'm trying to get the MEMS microphone (components U21 and U20 on the STM32F746g-disco) to work with SAI. I save my microphone inputs into a buffer with 1000 8-bit values via HAL_SAI_Receive_DMA. Below I have written my MX_SAI_Init() and HAL_SAI_MspInit(). I realise that the slots in the SAI audio frame are important, and from what I have learned I have initialized 4 slots with 2 active, 1 and 3.
As of now, the input buffer fills every adress with the value 255. I have been looking around the forum for quite some time and gotten a bit further, but it would be very helpful if someone with more experience with SAI could give me feedback on my initialization. Is this initialization correct in order to get input working with the MEMS microphones?
Initialization code
static void MX_SAI1_Init(void)
{
hsai_BlockA1.Instance = SAI1_Block_A;
hsai_BlockA1.Init.Protocol = SAI_FREE_PROTOCOL;
hsai_BlockA1.Init.AudioMode = SAI_MODEMASTER_RX;
hsai_BlockA1.Init.DataSize = SAI_DATASIZE_8;
hsai_BlockA1.Init.FirstBit = SAI_FIRSTBIT_MSB;
hsai_BlockA1.Init.ClockStrobing = SAI_CLOCKSTROBING_FALLINGEDGE;
hsai_BlockA1.Init.Synchro = SAI_ASYNCHRONOUS;
hsai_BlockA1.Init.OutputDrive = SAI_OUTPUTDRIVE_DISABLE;
hsai_BlockA1.Init.NoDivider = SAI_MASTERDIVIDER_ENABLE;
hsai_BlockA1.Init.FIFOThreshold = SAI_FIFOTHRESHOLD_FULL;
hsai_BlockA1.Init.AudioFrequency = SAI_AUDIO_FREQUENCY_44K;
hsai_BlockA1.Init.SynchroExt = SAI_SYNCEXT_DISABLE;
hsai_BlockA1.Init.MonoStereoMode = SAI_STEREOMODE;
hsai_BlockA1.Init.CompandingMode = SAI_NOCOMPANDING;
hsai_BlockA1.FrameInit.FrameLength = 32;
hsai_BlockA1.FrameInit.ActiveFrameLength = 1;
hsai_BlockA1.FrameInit.FSDefinition = SAI_FS_CHANNEL_IDENTIFICATION;
hsai_BlockA1.FrameInit.FSPolarity = SAI_FS_ACTIVE_HIGH;
hsai_BlockA1.FrameInit.FSOffset = SAI_FS_FIRSTBIT;
hsai_BlockA1.SlotInit.FirstBitOffset = 0;
hsai_BlockA1.SlotInit.SlotSize = SAI_SLOTSIZE_DATASIZE;
hsai_BlockA1.SlotInit.SlotNumber = 4;
hsai_BlockA1.SlotInit.SlotActive = SAI_SLOTACTIVE_1 | SAI_SLOTACTIVE_3;
if (HAL_SAI_Init(&hsai_BlockA1) != HAL_OK)
{
Error_Handler();
}
}void HAL_SAI_MspInit(SAI_HandleTypeDef* hsai)
{
GPIO_InitTypeDef GPIO_InitStruct;
/* SAI1 */
if(hsai->Instance==SAI1_Block_A)
{
/* Peripheral clock enable */
if (SAI1_client == 0)
{
__HAL_RCC_SAI1_CLK_ENABLE();
}
SAI1_client ++;
/**SAI1_A_Block_A GPIO Configuration
PE4 ------> SAI1_FS_A
PE5 ------> SAI1_SCK_A
PE6 ------> SAI1_SD_A
*/
GPIO_InitStruct.Pin = GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF6_SAI1;
HAL_GPIO_Init(GPIOE, &GPIO_InitStruct);
/* Peripheral DMA init*/
hdma_sai1_a.Instance = DMA2_Stream1;
hdma_sai1_a.Init.Channel = DMA_CHANNEL_0;
hdma_sai1_a.Init.Direction = DMA_PERIPH_TO_MEMORY;
hdma_sai1_a.Init.PeriphInc = DMA_PINC_DISABLE;
hdma_sai1_a.Init.MemInc = DMA_MINC_ENABLE;
hdma_sai1_a.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
hdma_sai1_a.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
hdma_sai1_a.Init.Mode = DMA_CIRCULAR;
hdma_sai1_a.Init.Priority = DMA_PRIORITY_HIGH;
hdma_sai1_a.Init.FIFOMode = DMA_FIFOMODE_DISABLE;
if (HAL_DMA_Init(&hdma_sai1_a) != HAL_OK)
{
Error_Handler();
}
/* Several peripheral DMA handle pointers point to the same DMA handle.
Be aware that there is only one stream to perform all the requested DMAs. */
__HAL_LINKDMA(hsai,hdmarx,hdma_sai1_a);
// Comment one of the links in order to make HAL_SAI_DMAStop() working properly.
// __HAL_LINKDMA(hsai,hdmatx,hdma_sai1_a);
}
}Thank you,