本人刚刚学完51单片机，知道串口每次只能发送一个字节的数据，32是不是一次能发送多个字节呢？程序如下，就是我发送aaaaaaa这7个字节，电脑也能显示这7个字节出来，是不是进行了7次中断呢？求大神们解决，小弟感激不尽



#include "stm32f10x.h"

void USART_INIT(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
USART_InitTypeDef  USART_InitStruct;
NVIC_InitTypeDef   NVIC_InitStruct;

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);   //´®¿ÚºÍio¿ÚµÄʱÖÓʹÄÜ

GPIO_InitStruct.GPIO_Mode=GPIO_Mode_AF_PP;
GPIO_InitStruct.GPIO_Pin=GPIO_Pin_9;
GPIO_InitStruct.GPIO_Speed=GPIO_Speed_10MHz;
GPIO_Init(GPIOA,&GPIO_InitStruct);//io¿ÚģʽÉèÖã¬ÊÇʲôģʽ²é¿´stm32ÖÐÎIJο¼ÊÖ²á

GPIO_InitStruct.GPIO_Mode=GPIO_Mode_IN_FLOATING;
GPIO_InitStruct.GPIO_Pin=GPIO_Pin_10;
GPIO_InitStruct.GPIO_Speed=GPIO_Speed_10MHz;
GPIO_Init(GPIOA,&GPIO_InitStruct);//io¿ÚģʽÉèÖã¬ÊÇʲôģʽ²é¿´stm32ÖÐÎIJο¼ÊÖ²á

USART_InitStruct.USART_BaudRate=115200;
USART_InitStruct.USART_HardwareFlowControl=USART_HardwareFlowControl_None;
USART_InitStruct.USART_Mode=USART_Mode_Rx|USART_Mode_Tx;
USART_InitStruct.USART_Parity=USART_Parity_No;
USART_InitStruct.USART_StopBits=USART_StopBits_1;
USART_InitStruct.USART_WordLength=USART_WordLength_8b;
USART_Init(USART1,&USART_InitStruct);//´®¿ÚµÄ³õʼ»¯

USART_Cmd(USART1,ENABLE);//ʹÄÜ´®¿Ú

USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);//´®¿ÚÖжϵĿªÆô

NVIC_InitStruct.NVIC_IRQChannel=USART1_IRQn;
NVIC_InitStruct.NVIC_IRQChannelCmd=ENABLE;
NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority=2;
NVIC_InitStruct.NVIC_IRQChannelSubPriority=2;
NVIC_Init(&NVIC_InitStruct);//Öжϳõʼ»¯

}
void  USART1_IRQHandler(void)
{
   int res,k=0;
    if(USART_GetITStatus(USART1,USART_IT_RXNE))//Öжϱê־λѰÕÒ
  {
    res=USART_ReceiveData(USART1);
     USART_SendData(USART1,res);
  }
  
}
int main(void)
{
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
USART_INIT();
while(1);
}