Debugging - "Download verified successfully" then Shuts Down

[TomHebe]

I am trying to debug an SDMMC application with FATFS. I simply selected the peripherals and generated code using STMCubeMX. Upon trying to debug, the program is successfully flashed however, it then exits debug mode.

When I comment out the  MX_FATFS_Init(); function, debugging works as normal. Why would this be the case?

```main.c

/* USER CODE BEGIN Header */

/**

******************************************************************************

* @file : main.c

* @brief : Main program body

******************************************************************************

* @attention

*

* Copyright (c) 2025 STMicroelectronics.

* All rights reserved.

*

* This software is licensed under terms that can be found in the LICENSE file

* in the root directory of this software component.

* If no LICENSE file comes with this software, it is provided AS-IS.

*

******************************************************************************

*/

/* USER CODE END Header */

/* Includes ------------------------------------------------------------------*/

#include "main.h"

#include "fatfs.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 ---------------------------------------------------------*/

SD_HandleTypeDef hsd2;

UART_HandleTypeDef huart4;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/

void SystemClock_Config(void);

static void MPU_Config(void);

static void MX_GPIO_Init(void);

static void MX_SDMMC2_SD_Init(void);

static void MX_UART4_Init(void);

/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/

/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**

* @brief The application entry point.

* @retval int

*/

int main(void)

{

/* USER CODE BEGIN 1 */

/* USER CODE END 1 */

/* MPU Configuration--------------------------------------------------------*/

MPU_Config();

/* 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_FATFS_Init();

MX_SDMMC2_SD_Init();

MX_UART4_Init();

/* USER CODE BEGIN 2 */

/* 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 = {0};

RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

/** Supply configuration update enable

*/

HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);

/** Configure the main internal regulator output voltage

*/

__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);

while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}

/** Initializes the RCC Oscillators according to the specified parameters

* in the RCC_OscInitTypeDef structure.

*/

RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;

RCC_OscInitStruct.HSIState = RCC_HSI_DIV1;

RCC_OscInitStruct.HSICalibrationValue = 64;

RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;

RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;

RCC_OscInitStruct.PLL.PLLM = 4;

RCC_OscInitStruct.PLL.PLLN = 12;

RCC_OscInitStruct.PLL.PLLP = 2;

RCC_OscInitStruct.PLL.PLLQ = 8;

RCC_OscInitStruct.PLL.PLLR = 2;

RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_3;

RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;

RCC_OscInitStruct.PLL.PLLFRACN = 0;

if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)

{

Error_Handler();

}

/** Initializes the CPU, AHB and APB buses clocks

*/

RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK

|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2

|RCC_CLOCKTYPE_D3PCLK1|RCC_CLOCKTYPE_D1PCLK1;

RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;

RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;

RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;

RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV1;

RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;

RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV1;

RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV1;

if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)

{

Error_Handler();

}

}

/**

* @brief SDMMC2 Initialization Function

* @param None

* @retval None

*/

static void MX_SDMMC2_SD_Init(void)

{

/* USER CODE BEGIN SDMMC2_Init 0 */

/* USER CODE END SDMMC2_Init 0 */

/* USER CODE BEGIN SDMMC2_Init 1 */

/* USER CODE END SDMMC2_Init 1 */

hsd2.Instance = SDMMC2;

hsd2.Init.ClockEdge = SDMMC_CLOCK_EDGE_RISING;

hsd2.Init.ClockPowerSave = SDMMC_CLOCK_POWER_SAVE_DISABLE;

hsd2.Init.BusWide = SDMMC_BUS_WIDE_4B;

hsd2.Init.HardwareFlowControl = SDMMC_HARDWARE_FLOW_CONTROL_DISABLE;

hsd2.Init.ClockDiv = 0;

/* USER CODE BEGIN SDMMC2_Init 2 */

/* USER CODE END SDMMC2_Init 2 */

}

/**

* @brief UART4 Initialization Function

* @param None

* @retval None

*/

static void MX_UART4_Init(void)

{

/* USER CODE BEGIN UART4_Init 0 */

/* USER CODE END UART4_Init 0 */

/* USER CODE BEGIN UART4_Init 1 */

/* USER CODE END UART4_Init 1 */

huart4.Instance = UART4;

huart4.Init.BaudRate = 115200;

huart4.Init.WordLength = UART_WORDLENGTH_8B;

huart4.Init.StopBits = UART_STOPBITS_1;

huart4.Init.Parity = UART_PARITY_NONE;

huart4.Init.Mode = UART_MODE_TX_RX;

huart4.Init.HwFlowCtl = UART_HWCONTROL_NONE;

huart4.Init.OverSampling = UART_OVERSAMPLING_16;

huart4.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;

huart4.Init.ClockPrescaler = UART_PRESCALER_DIV1;

huart4.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;

if (HAL_UART_Init(&huart4) != HAL_OK)

{

Error_Handler();

}

if (HAL_UARTEx_SetTxFifoThreshold(&huart4, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)

{

Error_Handler();

}

if (HAL_UARTEx_SetRxFifoThreshold(&huart4, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)

{

Error_Handler();

}

if (HAL_UARTEx_DisableFifoMode(&huart4) != HAL_OK)

{

Error_Handler();

}

/* USER CODE BEGIN UART4_Init 2 */

/* USER CODE END UART4_Init 2 */

}

/**

* @brief GPIO Initialization Function

* @param None

* @retval None

*/

static void MX_GPIO_Init(void)

{

GPIO_InitTypeDef GPIO_InitStruct = {0};

/* USER CODE BEGIN MX_GPIO_Init_1 */

/* USER CODE END MX_GPIO_Init_1 */

/* GPIO Ports Clock Enable */

__HAL_RCC_GPIOC_CLK_ENABLE();

__HAL_RCC_GPIOA_CLK_ENABLE();

__HAL_RCC_GPIOB_CLK_ENABLE();

__HAL_RCC_GPIOD_CLK_ENABLE();

/*Configure GPIO pin : SD_DET_Pin */

GPIO_InitStruct.Pin = SD_DET_Pin;

GPIO_InitStruct.Mode = GPIO_MODE_INPUT;

GPIO_InitStruct.Pull = GPIO_NOPULL;

HAL_GPIO_Init(SD_DET_GPIO_Port, &GPIO_InitStruct);

/* USER CODE BEGIN MX_GPIO_Init_2 */

/* USER CODE END MX_GPIO_Init_2 */

}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/* MPU Configuration */

void MPU_Config(void)

{

MPU_Region_InitTypeDef MPU_InitStruct = {0};

/* Disables the MPU */

HAL_MPU_Disable();

/** Initializes and configures the Region and the memory to be protected

*/

MPU_InitStruct.Enable = MPU_REGION_ENABLE;

MPU_InitStruct.Number = MPU_REGION_NUMBER0;

MPU_InitStruct.BaseAddress = 0x0;

MPU_InitStruct.Size = MPU_REGION_SIZE_4GB;

MPU_InitStruct.SubRegionDisable = 0x87;

MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;

MPU_InitStruct.AccessPermission = MPU_REGION_NO_ACCESS;

MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_DISABLE;

MPU_InitStruct.IsShareable = MPU_ACCESS_SHAREABLE;

MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;

MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;

HAL_MPU_ConfigRegion(&MPU_InitStruct);

/* Enables the MPU */

HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);

}

/**

* @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 */

__disable_irq();

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,

ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */

/* USER CODE END 6 */

}

#endif /* USE_FULL_ASSERT */