单片机c编程：*** WARNING L2:REFERENCE MADE TO UNRESOLVED EXTERNAL
程序：
#include
void mian()
{
while(1)
{
while(!RI); //检测是否收到数据 若收到则RI=1
RI=0; //清零
P1=0xfe;// 点亮P1口第一个发光二级管
}
}
Build target 'Target 1'
assembling STARTUP.A51...
compiling lesson7----.c...
linking...
*** WARNING L16:UNCALLED SEGMENT,IGNORED FOR OVERLAY PROCESS
SEGMENT:PR?MIAN?LESSON7____
*** WARNING L1:UNRESOLVED EXTERNAL SYMBOL
SYMBOL:MAIN
MODULE:E:\KEIL\C51\LIB\C51S.LIB C_INIT)
*** WARNING L2:REFERENCE MADE TO UNRESOLVED EXTERNAL
SYMBOL:MAIN
MODULE:E:\KEIL\C51\LIB\C51S.LIB C_INIT)
ADDRESS:0010H
Program Size:data=9.0 xdata=0 code=154
"lesson7----" - 0 Error(s),3 Warning(s).