51單片機(jī)信號(hào)接收問(wèn)題。。。高手幫看下~~~~

 #include <c8051f020.h>
#include <intrins.h>

#define uint unsigned int
#define uchar unsigned char
sbit SPEAKER=P3^3;
sbit SLEEP=P3^1;
sbit WX_RST=P3^2;
unsigned char warning_flag;
unsigned char chaomx_flag;
unsigned char flag;
unsigned char k;
unsigned int idata c_timer0;            //計(jì)時(shí)器
unsigned char data I2C_RAM[16];        //I2C數(shù)據(jù)交換RAM
unsigned char data bat_count;      //電池采樣計(jì)數(shù)
unsigned char code *pointer;
unsigned char idata uart0_se;            //uart0口接收開(kāi)始同步字和結(jié)束符個(gè)數(shù)
unsigned char idata uart0_num;            //uart0口接收、發(fā)送字符個(gè)數(shù)
unsigned char idata battery_volt;        //電池電壓 battery_volt=60*(battery_ad÷battery_base)
unsigned char idata battery_base[3];    //電池標(biāo)稱ad值和標(biāo)稱時(shí)的電壓
unsigned int idata battery_ad;            //電池當(dāng)前ad值
unsigned int idata battery_sampling[4]; //電池采樣周期瞬時(shí)值

void main(void)
{
//*************************************************************
//******系統(tǒng)初始化*********************************************
 /*初始化------------------------------*/ 
     P1MDIN=0xFF;
    EMI0CF=0x03;
    XBR0=0x04; //00000100B       /* UART0*/
//    XBR1=0x04; //00000100B       /* INT0 */
    XBR2=0x42; //01000010B       /* 弱上拉允許，允許交叉開(kāi)關(guān)，UART1不連到端口 */
//UART0初始化
    TL1=0xfd;            
    TH1=0xfd;            //定時(shí)器T1裝載值  FDH(9600), FAH(4800), F4H(2400), E8(1200)
    SCON0=0x50;          //設(shè)串口UART0為模式1(用于無(wú)線通信或PC通信)  (用T1)
    SCON1=0x50;
    //定時(shí)器設(shè)定
    CKCON=0x00;          //T0,T1,T2,T4使用SYSCLK的12分頻
    T2CON=0x04;           //T1為UART0串口波特率發(fā)生器，啟動(dòng)T2
    TMOD=0x21;            //T0為定時(shí)方式1,T1為8位自動(dòng)裝載為UART0串口波特率發(fā)生器
    TR1=1;                //啟動(dòng)T1
//DAC0設(shè)置
    
    P0MDOUT=0x01; //00000001B     /*P0配置*/
    P1MDOUT=0xff;                 /*P1*/
    P2MDOUT=0xff;                 /*P2*/
    P3MDOUT = 0xff; //11111111B  P3口配置 /*各個(gè)端口輸入時(shí)配置為漏極開(kāi)路，輸出時(shí)配置為推挽方式*/ 
    P74OUT=0x00;
    P4=P4&0xd3;                   /*ALE=0,A16=0(P4.3),LCDE=0(P4.2)*/               
    WDTCN=0xde;                   /*暫時(shí)禁止看門狗定時(shí)器*/
    WDTCN=0xad;
    SCON1=SCON1&0xfc;    //清TI1，RI1 

//外部中斷設(shè)置
    
    IE0=0;  /* 清中斷標(biāo)志 */
    ES0=1;            //開(kāi)放串口UART0中斷
    EA=1;         //開(kāi)總中斷
    AMX0SL=0x07;
//初始化

        P5=P5&0xfd;        //開(kāi)機(jī)點(diǎn)亮工作燈
         while (1);


}
void uart0_rt(void) interrupt 4 
 {
           k=0;
        if( _testbit_(RI0)) 
        {
        k=SBUF0;
        }
        
 }