IWDG无法写入预分频器和重载寄存器的原因？

我正在尝试检查 Nucleo-L4R5ZI 板上的 IWDG 功能。
参考可用于 NUCLEO-L496ZG 的示例代码，我为 L4R5ZI nucleo 创建了新项目。
我试图在调试模式下逐步进行。当调试器在 HAL_IWDG_Init(&hiwdg) 内部时，它能够使用 __HAL_IWDG_START(hiwdg) 成功启用 IWDG；
但是什么时候进入 IWDG_ENABLE_WRITE_ACCESS(hiwdg); 调试器进入系统内存。我通过暂停调试确认了这一点，它停在 0x1FFFxxxx 地址。同时，LD3 LED 发光。在我控制 LD3 的代码中没有任何地方。怎么了？请帮助。
代码如下：

/* Includes ------------------------------------------------------------------*/
#include "main.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 ---------------------------------------------------------*/
IWDG_HandleTypeDef hiwdg;
UART_HandleTypeDef hlpuart1;
UART_HandleTypeDef huart1;
UART_HandleTypeDef huart3;
PCD_HandleTypeDef hpcd_USB_OTG_FS;
/* USER CODE BEGIN PV */
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_LPUART1_UART_Init(void);
static void MX_USART3_UART_Init(void);
static void MX_USB_OTG_FS_PCD_Init(void);
static void MX_IWDG_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 */
/* 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_LPUART1_UART_Init();
MX_USART3_UART_Init();
MX_USB_OTG_FS_PCD_Init();
MX_IWDG_Init();
/* USER CODE BEGIN 2 */
if(HAL_IWDG_Init(&hiwdg) != HAL_OK)
{
/* Initialization Error */
Error_Handler();
}
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
/* Refresh IWDG: reload counter */
if(HAL_IWDG_Refresh(&hiwdg) != HAL_OK)
{
/* Refresh Error */
Error_Handler();
}
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_RESET);
while(1);
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
/**
* @brief IWDG Initialization Function
* @param None
* @retval None
*/
static void MX_IWDG_Init(void)
{
/* USER CODE BEGIN IWDG_Init 0 */
/* USER CODE END IWDG_Init 0 */
/* USER CODE BEGIN IWDG_Init 1 */
/* USER CODE END IWDG_Init 1 */
hiwdg.Instance = IWDG;
hiwdg.Init.Prescaler = IWDG_PRESCALER_32;
hiwdg.Init.Window = IWDG_WINDOW_DISABLE;
hiwdg.Init.Reload = 4095;
if (HAL_IWDG_Init(&hiwdg) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN IWDG_Init 2 */
/* USER CODE END IWDG_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_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
__HAL_RCC_GPIOG_CLK_ENABLE();
HAL_PWREx_EnableVddIO2();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_SET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOB, LD3_Pin|LD2_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(USB_PowerSwitchOn_GPIO_Port, USB_PowerSwitchOn_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : B1_Pin */
GPIO_InitStruct.Pin = B1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : PA0 */
GPIO_InitStruct.Pin = GPIO_PIN_0;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/*Configure GPIO pins : LD3_Pin LD2_Pin */
GPIO_InitStruct.Pin = LD3_Pin|LD2_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/*Configure GPIO pin : USB_PowerSwitchOn_Pin */
GPIO_InitStruct.Pin = USB_PowerSwitchOn_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(USB_PowerSwitchOn_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : USB_OverCurrent_Pin */
GPIO_InitStruct.Pin = USB_OverCurrent_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(USB_OverCurrent_GPIO_Port, &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 %drn", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/