STM32L476 - SAI - I2S Master Receive - MEMS MIC - Clock Problem
Hello,
I'm having trouble setting up the SAI peripheral clock on an STM32L476RET6 using Stm32CubeMX (Version 4.25.0).
I want to use the SAI2A as Master Receive on a MEMS MIC ICS43434 with I2S with FS = 48KHz. and SCK = 3.072MHz.
FS = MCLK / 256
So I put 12.288 in the field ''To SAI2 MHz'' and press enter but CubeMX suggests 12.235...
12.235 / 256 = 47.79KHz would be a bit out of the way I want. So I put 12.288 * 2 = 24.576 and CubeMX suggests 24,571 which would theoretically give me a FS of 47.99 ... KHz which I think is good but when compiling on Keil (V5.24.2.0) and measure with my oscilloscope:
FS = 58.7KHz insted 47.99 KHz
SCK = 3.74MHz insted 3.07MHzMCLK = 15Mhz insted 12.285MHzthe microphone responds okay but obviously with an incorrect sampling rate for my application.
I also configured another pin so that I could measure the clock generated by the HSI and measure 16Mhz as well as expected.on my board I have a crystal of 16MHz but when using it I have the same results as when I use HSI.I tried varying ''RCC_OscInitStruct.HSICalibrationValue'' but only got +-3KHz approximately.Anyone have any idea what I might be doing wrong?
Here is the code:
/* Includes ------------------------------------------------------------------*/
#include ''main.h''#include ''stm32l4xx_hal.h''/* USER CODE BEGIN Includes */
/* USER CODE END Includes */
/* Private variables ---------------------------------------------------------*/
SAI_HandleTypeDef hsai_BlockA2;/* USER CODE BEGIN PV */
/* Private variables ---------------------------------------------------------*//* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);static void MX_GPIO_Init(void);static void MX_SAI2_Init(void);/* USER CODE BEGIN PFP */
/* Private function prototypes -----------------------------------------------*//* USER CODE END PFP */
/* USER CODE BEGIN 0 */
/* USER CODE END 0 */
/**
* @brief The application entry point. * * @retval None */int main(void){ /* USER CODE BEGIN 1 *//* USER CODE END 1 */
/* MCU Configuration----------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init(); MX_SAI2_Init(); /* USER CODE BEGIN 2 */__HAL_SAI_ENABLE(&hsai_BlockA2); /* USER CODE END 2 *//* Infinite loop */
/* USER CODE BEGIN WHILE */ while (1) {/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */}
/**
* @brief System Clock Configuration * @retval None */void SystemClock_Config(void){RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_ClkInitTypeDef RCC_ClkInitStruct; RCC_PeriphCLKInitTypeDef PeriphClkInit;/**Initializes the CPU, AHB and APB busses clocks
*/ RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI; RCC_OscInitStruct.HSIState = RCC_HSI_ON; RCC_OscInitStruct.HSICalibrationValue = 16; RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON; RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI; RCC_OscInitStruct.PLL.PLLN = 43; RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7; RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2; RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV4; if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) { _Error_Handler(__FILE__, __LINE__); }/**Initializes the CPU, AHB and APB busses clocks
*/ RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2; RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK; RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1; RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1; RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{ _Error_Handler(__FILE__, __LINE__); }PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_SAI2;
PeriphClkInit.Sai2ClockSelection = RCC_SAI2CLKSOURCE_PLL; if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) { _Error_Handler(__FILE__, __LINE__); }HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSI, RCC_MCODIV_1);
/**Configure the main internal regulator output voltage
*/ if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK) { _Error_Handler(__FILE__, __LINE__); }/**Configure the Systick interrupt time
*/ HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);/**Configure the Systick
*/ HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);/* SysTick_IRQn interrupt configuration */
HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);}/* SAI2 init function */
static void MX_SAI2_Init(void){hsai_BlockA2.Instance = SAI2_Block_A;
hsai_BlockA2.Init.AudioMode = SAI_MODEMASTER_RX; hsai_BlockA2.Init.Synchro = SAI_ASYNCHRONOUS; hsai_BlockA2.Init.OutputDrive = SAI_OUTPUTDRIVE_DISABLE; hsai_BlockA2.Init.NoDivider = SAI_MASTERDIVIDER_ENABLE; hsai_BlockA2.Init.FIFOThreshold = SAI_FIFOTHRESHOLD_EMPTY; hsai_BlockA2.Init.AudioFrequency = SAI_AUDIO_FREQUENCY_48K; hsai_BlockA2.Init.SynchroExt = SAI_SYNCEXT_DISABLE; hsai_BlockA2.Init.MonoStereoMode = SAI_STEREOMODE; hsai_BlockA2.Init.CompandingMode = SAI_NOCOMPANDING; if (HAL_SAI_InitProtocol(&hsai_BlockA2, SAI_I2S_STANDARD, SAI_PROTOCOL_DATASIZE_24BIT, 2) != HAL_OK) { _Error_Handler(__FILE__, __LINE__); }}
/** Configure pins
PA8 ------> RCC_MCO*/static void MX_GPIO_Init(void){GPIO_InitTypeDef GPIO_InitStruct;
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOB_CLK_ENABLE(); __HAL_RCC_GPIOA_CLK_ENABLE();/*Configure GPIO pin : PA8 */
GPIO_InitStruct.Pin = GPIO_PIN_8; GPIO_InitStruct.Mode = GPIO_MODE_AF_PP; GPIO_InitStruct.Pull = GPIO_NOPULL; GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW; GPIO_InitStruct.Alternate = GPIO_AF0_MCO; HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);}
/* USER CODE BEGIN 4 */
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence. * @param file: The file name as string. * @param line: The line in file as a number. * @retval None */void _Error_Handler(char *file, int line){ /* USER CODE BEGIN Error_Handler_Debug */ /* User can add his own implementation to report the HAL error return state */ while(1) { } /* USER CODE END Error_Handler_Debug */}#ifdef USE_FULL_ASSERT
/** * @brief Reports the name of the source file and the source line number * where the assert_param error has occurred. * @param file: pointer to the source file name * @param line: assert_param error line source number * @retval None */void assert_failed(uint8_t* file, uint32_t line){ /* USER CODE BEGIN 6 */ /* User can add his own implementation to report the file name and line number, tex: printf(''Wrong parameters value: file %s on line %d\r\n'', file, line) */ /* USER CODE END 6 */}#endif /* USE_FULL_ASSERT */Thanks!
