printf 出来怎么老是多了个尾巴 打印出来最后总是多了个30 04

liujinyi999

     不知道怎么回事，打印完了后面总是多出来个30 04       

#include "stm32f10x.h"
#include <stdio.h>
#include "stm32f10x_usart.h"

int main(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
  USART_InitTypeDef USART_InitStructure;
/* Enable GPIO clock */
 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
 RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
 /* Configure USART Tx as alternate function push-pull */
 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
 GPIO_Init(GPIOA, &GPIO_InitStructure);
 /* Configure USART Rx as input floating */
 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
 GPIO_Init(GPIOA, &GPIO_InitStructure);
 
 

 USART_InitStructure.USART_BaudRate = 9600;
 USART_InitStructure.USART_WordLength = USART_WordLength_8b;
 USART_InitStructure.USART_StopBits = USART_StopBits_1;
 USART_InitStructure.USART_Parity = USART_Parity_No;
 USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
 USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
 /* USART configuration */
 USART_Init(USART1, &USART_InitStructure);
 /* Enable USART */
 USART_Cmd(USART1, ENABLE);
 USART_ClearFlag(USART1, USART_FLAG_TC);
 
 
 printf("aaa");

}

  int fputc(int ch, FILE *f)
{
  USART_SendData(USART1, (unsigned char) ch);
  while (!(USART1->SR & USART_FLAG_TXE));
  return (ch);
}

//打印出来就是 61 61 61 30 04

正点原子

比较奇怪....
试试我们的代码.