一个是修改SystemClock_Config函数中的参数和时钟来源，另一个是修改stm32f4xx_hal_conf.h中HSE_VALUE的值为25000000。
下面是修改前后的git diff

diff --git a/drivers/board.c b/drivers/board.c
index 4fb1fee..bbc8096 100644
--- a/drivers/board.c
+++ b/drivers/board.c
@@ -27,13 +27,12 @@ void SystemClock_Config(void)
   __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
   /** Initializes the CPU, AHB and APB busses clocks
   */
-  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
-  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
-  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
+  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
+  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
-  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
-  RCC_OscInitStruct.PLL.PLLM = 8;
-  RCC_OscInitStruct.PLL.PLLN = 168;
+  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
+  RCC_OscInitStruct.PLL.PLLM = 25;
+  RCC_OscInitStruct.PLL.PLLN = 336;
   RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
   RCC_OscInitStruct.PLL.PLLQ = 4;
   if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
diff --git a/drivers/stm32f4xx_hal_conf.h b/drivers/stm32f4xx_hal_conf.h
index 9db422a..aeb27fa 100644
--- a/drivers/stm32f4xx_hal_conf.h
+++ b/drivers/stm32f4xx_hal_conf.h
@@ -105,7 +105,7 @@
   *        (when HSE is used as system clock source, directly or through the PLL).
   */
 #if !defined  (HSE_VALUE)
-  #define HSE_VALUE    ((uint32_t)8000000U) /*!< Value of the External oscillator in Hz */
+  #define HSE_VALUE    ((uint32_t)25000000U) /*!< Value of the External oscillator in Hz */
 #endif /* HSE_VALUE */

 #if !defined  (HSE_STARTUP_TIMEOUT)