How to have access to the output data of the 2 digital microphones of the STM32L475VGT6 device (Discovery kit) ?

Lionel_D · ‎2020-03-31

Hi,

I'm working on a project where I need to make "sound recognition". In my case, I have to detect the nature of an object (paper, metal, glass etc.) based on its sound. To do that I envisage to use deep learning and thus to use the STM32CubeAI package.

My general question is first : is there a tutoriel of similar or equivalent project to help me to achieve what I want to do ?

A more specific question : How to have access to the output data of the 2 digital microphones of the STM32L475VGT6 (discovery kit), : I'm able to have access to the temperature values with the code below, I'm searching an equivalent code to have access to the data provided by the 2 digital microphones, especially the necessary header files :

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2020 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */
 
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "stm32l475e_iot01.h"
#include "stm32l475e_iot01_tsensor.h"
#include <math.h>
#include <stdio.h>
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
 
/* USER CODE END Includes */
 
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
 
/* USER CODE END PTD */
 
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
 
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
 
/* USER CODE END PM */
 
/* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart1;
float temp_value = 0; // Measured temperature value
char str_tmp[100] = ""; // Formatted message to display the temperature value
uint8_t msg1[] = "****** Temperature values measurement ******\n\n\r";
uint8_t msg2[] = "=====> Initialize Temperature sensor HTS221 \r\n";
uint8_t msg3[] = "=====> Temperature sensor HTS221 initialized \r\n ";
 
/* USER CODE BEGIN PV */
 
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART1_UART_Init(void);
/* USER CODE BEGIN PFP */
 
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
int _write(int file, char *ptr, int len)
{
	HAL_UART_Transmit( &huart1, (uint8_t*)ptr, len, HAL_MAX_DELAY );
	return len;
}
 
/* USER CODE END 0 */
 
/**
  * @brief  The application entry point.
  * @retval int
  */
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_USART1_UART_Init();
  /* USER CODE BEGIN 2 */
 
  HAL_UART_Transmit(&huart1,msg1,strlen(msg1),1000);
  HAL_UART_Transmit(&huart1,msg2,strlen(msg2),1000);
  BSP_TSENSOR_Init();
  HAL_UART_Transmit(&huart1,msg3,strlen(msg3),1000);
  printf( "Hello world!\r\n" );
 
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
	  temp_value = BSP_TSENSOR_ReadTemp();
	  /* int tmpInt1 = temp_value;
	  float tmpFrac = temp_value - tmpInt1;
	  int tmpInt2 = trunc(tmpFrac * 100);
	  snprintf(str_tmp,100," TEMPERATURE = %d.%02d\n\r", tmpInt1, tmpInt2);*/
	  snprintf(str_tmp,100," TEMPERATURE = %0.4f\n\r", temp_value);
	  HAL_UART_Transmit(&huart1,( uint8_t * )str_tmp,strlen(str_tmp),1000);
  }
  /* USER CODE END 3 */
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
 
  /** Initializes the CPU, AHB and APB busses clocks 
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSICalibrationValue = 0;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_6;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** 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_MSI;
  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_0) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART1;
  PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_PCLK2;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure the main internal regulator output voltage 
  */
  if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief USART1 Initialization Function
  * @param None
  * @retval None
  */
static void MX_USART1_UART_Init(void)
{
 
  /* USER CODE BEGIN USART1_Init 0 */
 
  /* USER CODE END USART1_Init 0 */
 
  /* USER CODE BEGIN USART1_Init 1 */
 
  /* USER CODE END USART1_Init 1 */
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 115200;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_TX_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  huart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART1_Init 2 */
 
  /* USER CODE END USART1_Init 2 */
 
}
 
/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
 
	GPIO_InitTypeDef GPIO_InitStruct = {0};
 
	  /* GPIO Ports Clock Enable */
	  __HAL_RCC_GPIOB_CLK_ENABLE();
 
	  /*Configure GPIO pins : PB6 PB7 */
	  GPIO_InitStruct.Pin = GPIO_PIN_6|GPIO_PIN_7;
	  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
	  GPIO_InitStruct.Pull = GPIO_NOPULL;
	  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
	  GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
	  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
 
/* USER CODE END 4 */
 
/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
 
  /* 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 */
 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

I think you for your listening.

Regards,

Lionel

JNord · ‎2020-05-06

PDM microphones on the STM32L4 are accessed using the Serial Audio Interface pheripheral (SAI). In particular PDM uses DFSDM type filters, so this is a good keyword when searching for information. Here is an example for STM32L476G-EVAL that should be adaptable to your board.

https://github.com/STMicroelectronics/STM32CubeL4/tree/master/Projects/STM32L476G-EVAL/Examples/DFSDM/DFSDM_AudioRecord

Regards, Jon Nordby. Soundsensing AS - experts in on-edge Audio Machine Learning