51 MCU + ESP8266 lights up LED lights

ESP8266 module adopts STA working mode. First, use the serial port debugging assistant on the computer to set the ESP8266 module to STA mode and baud rate 9600. The specific instructions are as follows:
1. Set AP mode AT+CWMODE=2
2. Reset takes effect AT+RST
3. Configure hotspot AT+CWSAP="test","12345678",1,3
In this way, even if ESP8266 is reset, this information will not be erased. You can directly use the following instructions to
connect the microcontroller to ESP8266. Be sure to pay attention to the common ground between the two, otherwise ESP8266 will not work properly. The ESP8266 power supply must be 3.3V, and 5V does not seem to work. The EN pin of ESP8266 is connected to a 1K ohm resistor and then to a 3.3V power supply.

#include
typedef unsigned char u8;
typedef unsigned int u16;
sbit LED = P1^0;u8 dat;
void Init(void); //Serial port initialization function
void Delay_ms(u16 n);//delay sub-function
void Sent_ZF(u8 dat);//send a byte
void AT_Send_String(u8 *string);//send string
void ESP8266_Init();//ESP8266 initialization
void Init(void) //Serial port initialization function
{

        TMOD=0x20; //Timer working mode 2, 8-bit automatic reload (0010 0000)
        TL1=0xfd; //Load initial value
        TH1=0xfd;               
        TR1=1; //Start timer 1
        REN=1; //Allow serial port to receive data
        SM0=0; //Working mode 1, 10-bit asynchronous reception and transmission
        SM1=1;   
        EA=1; //Open global interrupt control
        ES=1; //Open serial port interrupt
}

void main()
{
    Init();
    ESP8266_Init();
    while(1);
}

void Sent_ZF(u8 dat) //Send a byte
{
        ES = 0;
        TI=0;
        SBUF = dat;
        while(!TI);
        TI = 0;
        ES = 1;
}
void Delay_ms(u16 n) //Delay subroutine
{
        unsigned int i,j;
        for(i=0;i        for(j=0;j<123;j++);
}

void AT_Send_String(u8 *string) //Send string
{
  while(*string!='')
  {
    Sent_ZF(*string);
        string++;
                Delay_ms(10);
  }

}
void ESP8266_Init() //ESP8266 initialization
{       
         AT_Send_String("AT+RSTrn"); //Restart moduleDelay_ms
        (10000);
        Delay_ms(10000);
    AT_Send_String("AT+CIPMUX=1rn"); //Set to multi-connection mode, start moduleDelay_ms
        (10000);
        Delay_ms(10000);
  AT_Send_String("AT+CIPSERVER=1,8080rn"); //Server port setting
          Delay_ms(10000);
        Delay_ms(10000);
}

void InterruptUART() interrupt 4 //Control the small light switch
{
        RI= 0; //Clear
        dat= SBUF; //The received data is stored in SBUF
          {
         if(dat=='o')
                                 {
                                         LED =0;   
                                 }
                                 if(dat=='f')  
                                 {                                                 
                                    LED =1;
                                 }                                         
          }
}
Download a software called Network Debug Assistant on your phone. The IP address is 192.168.4.1 (it seems to be the same port), and the port number is 8080. After the connection is successful, send f or o to control the LED light switch.