1.打开STM32CubeMX选择好对应的芯片，打开IWDG

 2.打开串口1进行调试

 3.配置好时钟

 4.写好项目名称，选好开发环境，最后获取代码。 

5.打开工程，点击魔术棒，勾选Use Micro LIB

 6.修改main.c

#include "main.h"
#include "iwdg.h"
#include "usart.h"
#include "gpio.h"
#include <stdio.h>
#include <stm32_hal_legacy.h>


void SystemClock_Config(void);

extern	IWDG_HandleTypeDef hiwdg;

void PWR_Enter_Standby(void)
{
		__HAL_RCC_PWR_CLK_ENABLE();
		if (__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET)
		{
			__HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);

			if (__HAL_PWR_GET_FLAG(PWR_FLAG_WUF2) != RESET)
			{
				__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF2);
			}

			if (__HAL_PWR_GET_FLAG(PWR_FLAG_WUF4) != RESET)
			{
				__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF4);
			}
		}
		HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN2_HIGH);
		__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF2);
		//HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN4_HIGH);
		HAL_PWR_EnterSTANDBYMode();
}
 

void IWDG_OBProgram(void)
{
  /* 配置用户选项字节：在停止模式下冻结独立看门狗计数器 */
  FLASH_OBProgramInitTypeDef obprogram_init;
  /* 读取用户选项字节 */
  HAL_FLASHEx_OBGetConfig(&obprogram_init);
  
	printf("SYS USERConfig = 0x%x\r\n", obprogram_init.USERConfig);
	/* 判断FLASH_OPTR寄存器的IWDG_STDBY位是否置位（不判断也行） */
  if(obprogram_init.USERConfig & FLASH_OPTR_IWDG_STDBY)
  {
		/* 置位则清零IWDG_STOP位 */
		obprogram_init.OptionType = OPTIONBYTE_USER;
		obprogram_init.USERType = OB_USER_IWDG_STDBY;
		obprogram_init.USERConfig = OB_IWDG_STDBY_FREEZE; 
		obprogram_init.RDPLevel = OB_RDP_LEVEL_0;		
		/* 以下流程是根据手册上提供的 */
		HAL_FLASH_Unlock();
		HAL_FLASH_OB_Unlock();
		HAL_FLASHEx_OBProgram(&obprogram_init);
		HAL_FLASH_OB_Lock();
		HAL_FLASH_Lock();
		/* OBL_LAUNCH：选项字节重载位，用来生效上述更改(如果OPTLOCK为0，将此位置1，则会导致复位，如果 OPTLOCK为1，则此位无法写入,MCU复位后此位默认置1) */
		HAL_FLASH_OB_Launch();

		HAL_FLASHEx_OBGetConfig(&obprogram_init);
		printf("SET USERConfig = 0x%x\r\n", obprogram_init.USERConfig);
  }
}

int main(void)
{
	HAL_Init();
	SystemClock_Config();
	HAL_Delay(1000);

	MX_GPIO_Init();
	MX_USART1_UART_Init();
	/* USER CODE BEGIN 2 */
	MX_IWDG_Init();
	IWDG_OBProgram();
	printf("code init \r\n");

  while (1)
  {
		/* USER CODE END WHILE */
		HAL_IWDG_Refresh(&hiwdg); 
		//HAL_Delay(500);
		printf("PWR_Enter_Standby\r\n");
		PWR_Enter_Standby();
		printf("code start\r\n");
		/* 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};

  /** Configure the main internal regulator output voltage
  */
  HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSIDiv = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.LSIState = RCC_LSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV1;
  RCC_OscInitStruct.PLL.PLLN = 8;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
  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_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}

/* 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 */
  __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 */

7.串口打印，修改了OB_USER_IWDG_STDBY，系统看门狗复位一次后就没有再复位了。

 源码链接：跳转链接