Unable to reinitialize SAI peripheral

[pborto]

Hi,

I'm working with self designed board (STM32F765 MCU) and currently able to initialize SAI2 peripheral to work with codec in DMA mode.

At some point in my code, I need to change the sample rate of my codec (through MCLK).

The sequence of operations is basically as follows:

//1. DeInit SAI
HAL_SAI_DeInit(&hsai_BlockB2); //Deinit SAI_MODEMASTER_TX block set at old AudioFrequency
HAL_SAI_DeInit(&hsai_BlockA2); //Deinit SAI_MODESLAVE_RX block

//2 Init SAI with new freq. SAI_AUDIO_FREQUENCY_96K
hsai_BlockA2.Instance = SAI2_Block_A;
hsai_BlockA2.Init.AudioMode = SAI_MODESLAVE_RX;
hsai_BlockA2.Init.Synchro = SAI_SYNCHRONOUS;
hsai_BlockA2.Init.OutputDrive = SAI_OUTPUTDRIVE_DISABLE;
hsai_BlockA2.Init.FIFOThreshold = SAI_FIFOTHRESHOLD_1QF;
hsai_BlockA2.Init.SynchroExt = SAI_SYNCEXT_DISABLE;
hsai_BlockA2.Init.MonoStereoMode = SAI_STEREOMODE;
hsai_BlockA2.Init.CompandingMode = SAI_NOCOMPANDING;
hsai_BlockA2.Init.TriState = SAI_OUTPUT_NOTRELEASED;
if (HAL_SAI_InitProtocol(&hsai_BlockA2, SAI_I2S_STANDARD, SAI_PROTOCOL_DATASIZE_16BIT, 2) != HAL_OK)
{
Error_Handler();
}

hsai_BlockB2.Instance = SAI2_Block_B;
hsai_BlockB2.Init.AudioMode = SAI_MODEMASTER_TX;
hsai_BlockB2.Init.Synchro = SAI_ASYNCHRONOUS;
hsai_BlockB2.Init.OutputDrive = SAI_OUTPUTDRIVE_ENABLE;
hsai_BlockB2.Init.NoDivider = SAI_MASTERDIVIDER_ENABLE;
hsai_BlockB2.Init.FIFOThreshold = SAI_FIFOTHRESHOLD_1QF;
hsai_BlockB2.Init.AudioFrequency = SAI_AUDIO_FREQUENCY_96K;
hsai_BlockB2.Init.SynchroExt = SAI_SYNCEXT_DISABLE;
hsai_BlockB2.Init.MonoStereoMode = SAI_STEREOMODE;
hsai_BlockB2.Init.CompandingMode = SAI_NOCOMPANDING;
hsai_BlockB2.Init.TriState = SAI_OUTPUT_NOTRELEASED;
if (HAL_SAI_InitProtocol(&hsai_BlockB2, SAI_I2S_STANDARD, SAI_PROTOCOL_DATASIZE_16BIT, 2) != HAL_OK)
{
Error_Handler();
}

//3 custom function that reinit codec
Codec_Init();

//4. restart DMA tx and rx

if(HAL_OK != HAL_SAI_Transmit_DMA(&hsai_BlockB2, (uint8_t *)txAddr, Size))

{

Error_Handler();

}

if(HAL_OK != HAL_SAI_Receive_DMA(&hsai_BlockA2, (uint8_t *)rxAddr, Size))

{

Error_Handler();

}

The problem arises inside HAL_SAI_Transmit_DMA(&hsai_BlockB2, (uint8_t *)txAddr, Size), at the following :

if (HAL_DMA_Start_IT(hsai->hdmarx, (uint32_t)&hsai->Instance->DR, (uint32_t)hsai->pBuffPtr, hsai->XferSize) != HAL_OK)  

the system goes in:
Default_Handler:
Infinite_Loop:
b Infinite_Loop
.size Default_Handler, .-Default_Handler

The sequence of operations is the same at the start (working) and when I try to set the new frequency (not working) except for:

hsai_BlockB2.Init.AudioFrequency = SAI_AUDIO_FREQUENCY_8K; (working case)

hsai_BlockB2.Init.AudioFrequency = SAI_AUDIO_FREQUENCY_96K; (not working case)

I checked PeriphClkInitStruct settings and are ok for both cases.

I also verified that if I start directly by setting the frequency to 96k everything works; so it seems like something related to the reinitialization operation.

Thanks in advance for the support.

[LCE]

Did you stop DMA?

I'm doing that on a F767 this way:

• stop DMA (circular mode) with HAL_SAI_DMAStop(), that includes FIFO flush and SAI disable
• then I set the MCKDIV bits in CR1
• then restart DMA with HAL_SAI_Receive_DMA() (modified for DBM)

So no complete init / deinit. (I'm using HAL only for start / stop DMA)

/* clear and set sampling rate */
u32MckDivNew = some define depending on sampling rate for the divider...
SAI1_Block_A->CR1 &= ~SAI_xCR1_MCKDIV;
SAI1_Block_A->CR1 |= u32MckDivNew;

PS: I just see that probably the link between DMA and SAI is gone after your De-Init.

[pborto]

Hi LCE,

Thank you for your quick reply.

I tried first, as you suggested, to stop DMA with the function HAL_SAI_DMAStop(), but without success.

If I call HAL_SAI_DMAStop() at the same time as HAL_SAI_TxCpltCallback or HAL_SAI_RxCpltCallback, I get the following error: DMA_ERROR_NO_XFER.

If I make the call to HAL_SAI_DMAStop() somewhere else, I end up in the infinite loop of Default_Handler.

[Piranha]

I'm using HAL only for start / stop DMA

---

And, like everything in HAL, that is also broken...

https://community.st.com/t5/stm32-mcus-embedded-software/bug-stm32-hal-sai-abort-and-dma-stop-logic-is-flawed/td-p/54339

[LCE]

Thanks for that hint, I'll get back to this.