Question
STM32WB55 / NUCLEO-WB55RG PDM Clock issue?
I have an unexpected result, that bothers me for two days now: I use CubeMX 6.12.1 that I use with VSCode / STM extension V2.1.1. I connected a TDK3902-Evaluation PDM Microphone-board (datasheet and T3902 component datasheet), it needs between 1.0-3.3MHz clock for normal mode. (400-800khz LP mode).
I connected Vdd to 3.3V, GND to GND, select to GND, data to SAI1_D1 (PC3) and clock to SAI1_CK (PB8).
In CubeMX I activated SAI1, set the following options:
- PDM
- Mono
- 16khz (SAI1 clock set to 40.96 MHz)
- 16bit data/frame
In clock configuration:
If I probe the SAI1_CK pin (PB8) I see a 128 khz clock. Obviously this is too less and not correct, what am I overseeing here? Maybe a bug?
The code generated by CubeMX:
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/** Macro to configure the PLL multiplication factor
*/
__HAL_RCC_PLL_PLLM_CONFIG(RCC_PLLM_DIV5);
/** Macro to configure the PLL clock source
*/
__HAL_RCC_PLL_PLLSOURCE_CONFIG(RCC_PLLSOURCE_HSE);
/** Configure the main internal regulator output voltage
*/
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI48|RCC_OSCILLATORTYPE_HSI
|RCC_OSCILLATORTYPE_HSE|RCC_OSCILLATORTYPE_MSI;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.MSIState = RCC_MSI_ON;
RCC_OscInitStruct.HSI48State = RCC_HSI48_ON;
RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_10;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Configure the SYSCLKSource, HCLK, PCLK1 and PCLK2 clocks dividers
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK4|RCC_CLOCKTYPE_HCLK2
|RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.AHBCLK2Divider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.AHBCLK4Divider = RCC_SYSCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief Peripherals Common Clock Configuration
* @retval None
*/
void PeriphCommonClock_Config(void)
{
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
/** Initializes the peripherals clock
*/
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_SMPS;
PeriphClkInitStruct.SmpsClockSelection = RCC_SMPSCLKSOURCE_HSI;
PeriphClkInitStruct.SmpsDivSelection = RCC_SMPSCLKDIV_RANGE0;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN Smps */
/* USER CODE END Smps */
}
/**
* @brief SAI1 Initialization Function
* None
* @retval None
*/
static void MX_SAI1_Init(void)
{
/* USER CODE BEGIN SAI1_Init 0 */
/* USER CODE END SAI1_Init 0 */
/* USER CODE BEGIN SAI1_Init 1 */
/* USER CODE END SAI1_Init 1 */
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_16;
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.MckOverSampling = SAI_MCK_OVERSAMPLING_DISABLE;
hsai_BlockA1.Init.FIFOThreshold = SAI_FIFOTHRESHOLD_EMPTY;
hsai_BlockA1.Init.AudioFrequency = SAI_AUDIO_FREQUENCY_16K;
hsai_BlockA1.Init.MonoStereoMode = SAI_MONOMODE;
hsai_BlockA1.Init.CompandingMode = SAI_NOCOMPANDING;
hsai_BlockA1.Init.PdmInit.Activation = ENABLE;
hsai_BlockA1.Init.PdmInit.MicPairsNbr = 1;
hsai_BlockA1.Init.PdmInit.ClockEnable = SAI_PDM_CLOCK1_ENABLE;
hsai_BlockA1.FrameInit.FrameLength = 16;
hsai_BlockA1.FrameInit.ActiveFrameLength = 1;
hsai_BlockA1.FrameInit.FSDefinition = SAI_FS_STARTFRAME;
hsai_BlockA1.FrameInit.FSPolarity = SAI_FS_ACTIVE_LOW;
hsai_BlockA1.FrameInit.FSOffset = SAI_FS_FIRSTBIT;
hsai_BlockA1.SlotInit.FirstBitOffset = 0;
hsai_BlockA1.SlotInit.SlotSize = SAI_SLOTSIZE_DATASIZE;
hsai_BlockA1.SlotInit.SlotNumber = 2;
hsai_BlockA1.SlotInit.SlotActive = 0x00000003;
if (HAL_SAI_Init(&hsai_BlockA1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN SAI1_Init 2 */
/* USER CODE END SAI1_Init 2 */
}
/**
* Enable DMA controller clock
*/
static void MX_DMA_Init(void)
{
/* DMA controller clock enable */
__HAL_RCC_DMAMUX1_CLK_ENABLE();
__HAL_RCC_DMA1_CLK_ENABLE();
/* DMA interrupt init */
/* DMA1_Channel1_IRQn interrupt configuration */
HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);
}
The code is easy, for testing:
#define BUFFERPDMSIZE 128
uint16_t data[BUFFERPDMSIZE] = {0};
HAL_SAI_Receive_DMA(&hsai_BlockA1, (uint8_t*)data, BUFFERPDMSIZE);
And the callback with empty processing:
//Callback for dma
void HAL_SAI_RxHalfCpltCallback(SAI_HandleTypeDef *hsai)
{
printf("1st half of data received\n\r");
process_audio_data(data, BUFFERPDMSIZE/2);
}
void HAL_SAI_RxCpltCallback(SAI_HandleTypeDef *hsai)
{
printf("2nd half of data received\n\r");
process_audio_data(data + BUFFERPDMSIZE/2, BUFFERPDMSIZE/2);
}
void process_audio_data(uint16_t *data, uint16_t size)
{
printf("Data received\n\r");
for (int i = 0; i < size; i++)
{
printf("%d\n\r", data[i]);
}
printf("Data processed\n\r");
}
The callbacks are activated: terminal prints the printf statements, data is dec 65535/ 0xFFFF...