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使用外部高速晶振

外部高速晶振为8M（根据开发板上的晶振频率设置），使用 PLLCLK，HSE 选项

USART1 使用 Asynchronous，PA9，PA10引脚（USART1 引脚根据开发板上引脚设置）

设置MDK ARM，使用keil

printf 函数使用，需要勾选Use Micro LIB 复选框

Download 代码后即可运行，勾选Reset and Run 复选框

"Error: Not a genuine ST Device! Abort connection"

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../Core/Src/main.c(48): error:  #20: identifier "FILE" is undefined

需要包含头文件: stdio.h

/* USER CODE BEGIN Includes */#include "stdio.h"/* 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 ---------------------------------------------------------*/
UART_HandleTypeDef huart1;/* USER CODE BEGIN PV */
int fputc(int ch, FILE *f)
{while ((USART1->SR & 0X40) == 0);USART1->DR = (uint8_t) ch;return ch;
}/* USER CODE END PV */

  /* Infinite loop *//* USER CODE BEGIN WHILE */while (1){/* USER CODE END WHILE *//* USER CODE BEGIN 3 */printf("TEST\r\n");HAL_Delay(1000);}/* USER CODE END 3 */

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