怎样在串口中去添加重定向代码呢

首先将串口初始化，然后添加重定向代码
下面使用的是串口三，因此以串口三为例：

UART_HandleTypeDef huart3;
#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(&huart3, (uint8_t *)&ch, 1, 0x0001);
  return ch;
}
添加完代码后就可以使用printf进行打印了~