STM32F446 SAI Configuration StdPeriphLibrary

[sir]

Posted on June 15, 2016 at 13:01

Hello everyone.

I am a bit stuck with SAI configuration for STM32F446 MCU. What I want to get is a full duplex SAI, working with PCM-coded signal coming from bluetooth module. Now I am trying to configure the SAI bus. To do so I use StdPeripheral Drivers set. First, I select the clock source for SAI and configure its frequency:

void
PLLSAI_Config(
void
)

{

/* Configure PLLI2S prescalers */

/* PLLI2S_VCO : VCO_344M */

/* SAI_CLK(first level) = PLLI2S_VCO/PLLI2SQ = 344/7 = 142 Mhz */

RCC_PLLI2SConfig(16, 344, 2, 7, 2);

/* SAI_CLK_x = SAI_CLK(first level)/PLLI2SDIVQ = 142/1 = 142 Mhz */

RCC_SAIPLLI2SClkDivConfig(1);

/* Configure Clock source for SAI */

RCC_SAICLKConfig(RCC_SAIInstance_SAI1, RCC_SAICLKSource_PLLI2S);

/* Enable PLLI2S Clock */

RCC_PLLI2SCmd(ENABLE);

/* Wait till PLLI2S is ready */

while
(RCC_GetFlagStatus(RCC_FLAG_PLLI2SRDY) == RESET)

{

}

LOG_OUT(
''SAI clocks configured\n''
);

}

Second, I configure GPIO pins as alternate functions, no problem here. Third configure SAI bus, enable the interrupts, enable SAI:

SAI_InitTypeDef tx_cfg =

{

.SAI_Protocol = SAI_Free_Protocol,

.SAI_AudioMode = SAI_Mode_MasterTx,

.SAI_DataSize = SAI_DataSize_16b,

.SAI_FirstBit = SAI_FirstBit_MSB,

.SAI_ClockStrobing = SAI_ClockStrobing_RisingEdge,

.SAI_Synchro = SAI_Asynchronous,

.SAI_OUTDRIV = SAI_OutputDrive_Disabled,

.SAI_NoDivider = SAI_MasterDivider_Enabled,

.SAI_FIFOThreshold = SAI_FIFOThreshold_HalfFull,

};


SAI_InitTypeDef rx_cfg =

{

.SAI_Protocol = SAI_Free_Protocol,

.SAI_AudioMode = SAI_Mode_SlaveRx,

.SAI_DataSize = SAI_DataSize_16b,

.SAI_FirstBit = SAI_FirstBit_MSB,

.SAI_ClockStrobing = SAI_ClockStrobing_RisingEdge,

.SAI_Synchro = SAI_Synchronous,

.SAI_OUTDRIV = SAI_OutputDrive_Disabled,

.SAI_NoDivider = SAI_MasterDivider_Enabled,

.SAI_FIFOThreshold = SAI_FIFOThreshold_HalfFull,

};


SAI_FrameInitTypeDef frame_cfg =

{

.SAI_FrameLength = 16U * 2,

.SAI_ActiveFrameLength = 1U,

.SAI_FSDefinition = SAI_FS_StartFrame,

.SAI_FSPolarity = SAI_FS_ActiveLow,

.SAI_FSOffset = SAI_FS_BeforeFirstBit,

};


SAI_SlotInitTypeDef slot_cfg =

{

.SAI_FirstBitOffset = 0U,

.SAI_SlotSize = SAI_SlotSize_16b,

.SAI_SlotNumber = 2,

.SAI_SlotActive = SAI_SlotActive_ALL,

};


RCC_APB2PeriphClockCmd(RCC_APB2Periph_SAI1, ENABLE);


uint32_t tmpdiv = ((uint32_t)49152000) / (16000 * 512);

tx_cfg.SAI_MasterDivider = tmpdiv;

rx_cfg.SAI_MasterDivider = tmpdiv;


SAI_Init(SAI1_Block_A, &tx_cfg);

SAI_Init(SAI1_Block_B, &rx_cfg);

SAI_FrameInit(SAI1_Block_A, &frame_cfg);

SAI_FrameInit(SAI1_Block_B, &frame_cfg);

SAI_SlotInit(SAI1_Block_A, &slot_cfg);

SAI_SlotInit(SAI1_Block_B, &slot_cfg);


SAI_FlushFIFO(SAI1_Block_A);

SAI_FlushFIFO(SAI1_Block_B);


SAI_MonoModeConfig(SAI1_Block_A, SAI_MonoMode);

SAI_MonoModeConfig(SAI1_Block_B, SAI_MonoMode);


NVIC_SetPriority(SAI1_IRQn, 0);

NVIC_EnableIRQ(SAI1_IRQn);


uint32_t intsf = SAI_IT_FREQ | SAI_IT_OVRUDR | SAI_IT_AFSDET | SAI_IT_LFSDET | SAI_IT_CNRDY;

SAI_ITConfig(SAI1_Block_A, intsf, ENABLE);

SAI_ITConfig(SAI1_Block_B, intsf, ENABLE);


SAI_Cmd(SAI1_Block_A, ENABLE);

SAI_Cmd(SAI1_Block_B, ENABLE);

But then nothing happens, I don't have any interrupts or what is more strange I even don't have a clock on SCK pin of the MCU. Could someone give me any hints where to dig further? May be I messed up with configuration or clocks? Thanks! #audio #sai #pcm

[Amel NASRI]

Posted on June 27, 2016 at 13:58

Hi xoroxo,

I suggest you refer to the SAI_Audio example available in the F4 StdPeriph_Lib package (STM32F4xx_DSP_StdPeriph_Lib_V1.7.1\Project\STM32F4xx_StdPeriph_Examples\SAI\SAI_Audio). The example runs on STM32F429xx/439xx devices but you may take it as a start point to configure your SAI using STM32F446.You find dedicated SAI examples for STM32F446 devices if you use Cube: STM32Cube_FW_F4_V1.12.0\Projects\STM32446E_EVAL\Examples\SAI-Mayla-