修改HAL标准库用printf函数发送数据直接输出

主函数文件，请直接关注自己写上去的代码：

直接看43行代码：#include "stdio.h"//要添加这个头文件

还有97行到112行：实现用HAL库函数和printf函数发送数据

 /**
   ******************************************************************************
   * File Name          : main.c
   * Description        : Main program body
   ******************************************************************************
   ** This notice applies to any and all portions of this file
   * that are not between comment pairs USER CODE BEGIN and
   * USER CODE END. Other portions of this file, whether
   * inserted by the user or by software development tools
   * are owned by their respective copyright owners.
   *
   * COPYRIGHT(c) 2017 STMicroelectronics
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *   1. Redistributions of source code must retain the above copyright notice,
   *      this list of conditions and the following disclaimer.
   *   2. Redistributions in binary form must reproduce the above copyright notice,
   *      this list of conditions and the following disclaimer in the documentation
   *      and/or other materials provided with the distribution.
   *   3. Neither the name of STMicroelectronics nor the names of its contributors
   *      may be used to endorse or promote products derived from this software
   *      without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   ******************************************************************************
   */
 /* Includes ------------------------------------------------------------------*/
 #include "main.h"
 #include "stm32f1xx_hal.h"

 /* USER CODE BEGIN Includes */
 #include "stdio.h"//添加这个头文件
 /* USER CODE END Includes */

 /* Private variables ---------------------------------------------------------*/
 UART_HandleTypeDef huart1;

 /* USER CODE BEGIN PV */
 /* Private variables ---------------------------------------------------------*/

 /* USER CODE END PV */

 /* Private function prototypes -----------------------------------------------*/
 void SystemClock_Config(void);
 static void MX_GPIO_Init(void);
 static void MX_USART1_UART_Init(void);

 /* USER CODE BEGIN PFP */
 /* Private function prototypes -----------------------------------------------*/

 /* USER CODE END PFP */

 /* USER CODE BEGIN 0 */

 /* USER CODE END 0 */

 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_USART1_UART_Init();

   /* USER CODE BEGIN 2 */

 HAL_UART_Transmit (&huart1,"使用HAL库函数发送数据\n",,);
 printf("\n使用函数Printf函数发送数据\n");

 char t;
 while()
 {
     scanf("%c",&t);//接受的t的数值
     if(t=='')
     {
         HAL_GPIO_WritePin (GPIOB,GPIO_PIN_5,);//给低电平，红灯亮
     }
     if(t=='')
     {
         HAL_GPIO_WritePin (GPIOB,GPIO_PIN_5,);//给高电平，红灯灭
     }
 }

   /* USER CODE END 2 */

   /* Infinite loop */
   /* USER CODE BEGIN WHILE */
   while ()
   {
   /* USER CODE END WHILE */

   /* USER CODE BEGIN 3 */

   }
   /* USER CODE END 3 */

 }

 /** System Clock Configuration
 */
 void SystemClock_Config(void)
 {

   RCC_OscInitTypeDef RCC_OscInitStruct;
   RCC_ClkInitTypeDef RCC_ClkInitStruct;

     /**Initializes the CPU, AHB and APB busses clocks
     */
   RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
   RCC_OscInitStruct.HSIState = RCC_HSI_ON;
   RCC_OscInitStruct.HSICalibrationValue = ;
   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
   if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
   {
     _Error_Handler(__FILE__, __LINE__);
   }

     /**Initializes the CPU, AHB and APB busses clocks
     */
   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(__FILE__, __LINE__);
   }

     /**Configure the Systick interrupt time
     */
   HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/);

     /**Configure the Systick
     */
   HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

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

 /* USART1 init function */
 static void MX_USART1_UART_Init(void)
 {

   huart1.Instance = USART1;
   huart1.Init.BaudRate = ;
   huart1.Init.WordLength = UART_WORDLENGTH_8B;
   huart1.Init.StopBits = UART_STOPBITS_1;
   huart1.Init.Parity = UART_PARITY_NONE;
   huart1.Init.Mode = UART_MODE_TX_RX;
   huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
   huart1.Init.OverSampling = UART_OVERSAMPLING_16;
   if (HAL_UART_Init(&huart1) != HAL_OK)
   {
     _Error_Handler(__FILE__, __LINE__);
   }

 }

 /** Configure pins as
         * Analog
         * Input
         * Output
         * EVENT_OUT
         * EXTI
 */
 static void MX_GPIO_Init(void)
 {

   GPIO_InitTypeDef GPIO_InitStruct;

   /* GPIO Ports Clock Enable */
   __HAL_RCC_GPIOA_CLK_ENABLE();
   __HAL_RCC_GPIOB_CLK_ENABLE();

   /*Configure GPIO pin Output Level */
   HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, GPIO_PIN_RESET);

   /*Configure GPIO pin : PB5 */
   GPIO_InitStruct.Pin = GPIO_PIN_5;
   GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
   HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

 }

 /* USER CODE BEGIN 4 */

 /* USER CODE END 4 */

 /**
   * @brief  This function is executed in case of error occurrence.
   * @param  None
   * @retval None
   */
 void _Error_Handler(char * file, int line)
 {
   /* USER CODE BEGIN Error_Handler_Debug */
   /* User can add his own implementation to report the HAL error return state */
   while()
   {
   }
   /* 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

 /**
   * @}
   */ 

 /**
   * @}
 */ 

 /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

新建一个文件，随便命名，这是核心内容，修改标准库函数的，有点难理解！！！。

 #include "stdio.h"
 #include "stm32f1xx_hal.h"

 //这个变量是其他.c文件定义的
 extern UART_HandleTypeDef huart1;
 uint8_t ch;
 uint8_t ch_r;
 //重写这个函数,重定向printf函数到串口，意思就是说printf直接输出到串口，其默认输出到控制台的
 /*fputc*/
 int fputc(int c, FILE * f)
 {
     ch=c;
     HAL_UART_Transmit(&huart1,&ch,,);//发送串口
     return c;
 }

 //重定向scanf函数到串口 意思就是说接受串口发过来的数据，其默认是接受控制台的数据
 /*fgetc*/
 int fgetc(FILE * F)
 {
     HAL_UART_Receive (&huart1,&ch_r,,0xffff);//接收
     return ch_r;
 }