大家好 請問一下 我最近在做看門狗的實驗 但是看門狗一直不起作用 麻煩大家指導一下 以下是我的程式碼

#include "stm32f4xx_hal.h"

IWDG_HandleTypeDef hiwdg;
GPIO_InitTypeDef gpio_init;


void SystemClock_Config(void);
void Error_Handler(void);
static void MX_GPIO_Init(void);
static void MX_IWDG_Init(void);


int main(void)
{

  HAL_Init();
       
  SystemClock_Config();
       
  MX_GPIO_Init();
  MX_IWDG_Init();

        HAL_IWDG_Start(&hiwdg);
       
        while(1)
        {
               
        }
       
}

void SystemClock_Config(void)
{

  RCC_OscInitTypeDef RCC_OscInitStruct;
  RCC_ClkInitTypeDef RCC_ClkInitStruct;

  __HAL_RCC_PWR_CLK_ENABLE();

  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.LSIState = RCC_LSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  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();
  }

  HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);

  HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

  /* SysTick_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
}

/* IWDG init function */
static void MX_IWDG_Init(void)
{

  hiwdg.Instance = IWDG;
  hiwdg.Init.Prescaler = IWDG_PRESCALER_64;
  hiwdg.Init.Reload = 500;

        HAL_IWDG_Init(&hiwdg);
       
}


static void MX_GPIO_Init(void)
{

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOH_CLK_ENABLE();
        __HAL_RCC_GPIOB_CLK_ENABLE();
       
        gpio_init.Pin = GPIO_PIN_0;
        gpio_init.Mode = GPIO_MODE_OUTPUT_PP;
        gpio_init.Speed = GPIO_SPEED_FREQ_HIGH;
        gpio_init.Pull = GPIO_NOPULL;
       
        HAL_GPIO_Init(GPIOB,&gpio_init);
       
       
}


void Error_Handler(void)
{

  while(1)
  {
  }

}

#ifdef USE_FULL_ASSERT

void assert_failed(uint8_t* file, uint32_t line)
{


}

#endif