HAL 库使用printf函数

#include "main.h"
#include "adc.h"
#include "usart.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "stdio.h"
#ifdef __GNUC__
  #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
  #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif

PUTCHAR_PROTOTYPE
{
  HAL_UART_Transmit(&huart3,(uint8_t *)&ch,1,0xFFFF);//??????
  return ch;
}

/* 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 ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */

    float votagle=3.125;
    char ab[5]="test";
  /* 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_ADC_Init();
  MX_USART3_UART_Init();
  /* USER CODE BEGIN 2 */

 
 

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
        int i;
        
        printf("hello world\r\n");
        for(i=0;i<4;i++)
        {
        printf("%c",ab[i]);
        }
        printf("\n");
        printf("%s\r\n",ab);
        printf("%f\r\n",votagle);
        HAL_Delay(500);
  }
  /* USER CODE END 3 */
}

想使用printf，首先要以下代码。其实&huart3是我刚好要使用的串口，可根据自己需求修改

#include "stdio.h"
#ifdef __GNUC__
  #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
  #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif

PUTCHAR_PROTOTYPE
{
  HAL_UART_Transmit(&huart3,(uint8_t *)&ch,1,0xFFFF);//??????
  return ch;
}

然后我主函数中分别通过USART3输出字符串和浮点型

        int i;
        
        printf("hello world\r\n");
        for(i=0;i<4;i++)
        {
        printf("%c",ab[i]);
        }
        printf("\n");
        printf("%s\r\n",ab);
        printf("%f\r\n",votagle);
        HAL_Delay(500);
 

输出结果如下

 

 printf各种类型输出控制符如下

%d 输出整数

%ld 长整型

%u 输出无符号类型，输出无符号类型时也可以用%d

%c 输出一个字符

%s 输出字符串

%f 输出实数（小数点后6位，超过的四舍五入）