重写fput函数 

#include <stdio.h>#ifdef __GNUC__#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{HAL_UART_Transmit(&huart1, (uint8_t *)&ch,1,0xFFFF);return ch;}