#include<reg52.h>#define uchar unsigned charuchar a,flag;void main(){TMOD=0x20;TH1=0xfd;TL1=0xfd;TR1=1; REN=1;SM0=0;SM1=1;EA=1;ES=1;//PCON=0x80;while(1){if(flag==1){ES=0;flag=0;SBUF=a;while(!TI);TI=0;ES=1;}}}void serial() interrupt 4{ RI=0;a=SBUF;flag=1;}