STM32USART串口调节与printf重定义

首先，printf重定义后可以直接使用printf函数从串口发送数据

在usart.c中添加代码：

#ifdef __GNUC__

  /* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf

     set to 'Yes') calls __io_putchar() */

  #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)

#else

  #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)

#endif /* __GNUC__ */

/**

  * @brief  Retargets the C library printf function to the USART.

  * @param  None

  * @retval None

  */

PUTCHAR_PROTOTYPE

{

  /* Place your implementation of fputc here */

  /* e.g. write a character to the EVAL_COM1 and Loop until the end of transmission */

  HAL_UART_Transmit(&huart1, (uint8_t *)&ch, 1, 0xFFFF);

  return ch;

}

便可以在main中直接使用printf函数了

int main(void)

{

  HAL_Init();

  MX_GPIO_Init();

  MX_USART1_UART_Init();

  while (1)

  {

printf("\n\r 我是杨海鑫\n\r");

HAL_Delay(1000);

  }

}