单片机c语言用串口调试助手发送单片机接后发回来不相同 发11 12 13 14 15 16 17接ff 11 12 13 14 15 16

#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int
//sbit ledhong=P1^3;
//sbit rxd=P3^0;
//sbit ledlv=P1^2;
sbit led=P1^3;//1为灯指示灯亮0为灭
uchar aa=0;
uchar bb[7];
/*void delays()//1.3s
{
    uint c;
    for(c=0;c<32800;c++);
}*/
void main()
{
    uchar cc=0;
    EA=1;
    ES=1;
    REN=1;
    TI=0;
    RI=0;
    SM0=0;
    SM1=1;
    PCON=0x00;
    TMOD=0x20;
    TH1=0xe8;
    TL1=0xe8;
    TR1=1;
    while(1)
    {
            if(aa>6)
            {
                if(cc<7)
                {
                    SBUF=bb[cc];
                    while(!TI);
                    TI=0;
                    cc++;
                    led=0;
                }        
            }
        
    }
}
void ser() interrupt 4
{
    /*if(TI==1)
    {
        TI=0;
    }*/
    if(RI==1)
    {
        RI=0;
        if(aa<7)
        {bb[aa]=SBUF;}
        aa++;
    }
}