Circuit:



Code:




#include<reg51.h>
#include "UART_H_file.h" 
sbit motrf=P1^3; 
sbit motrb=P1^4;
sbit motlf=P1^5;
sbit motlb=P1^6;
void main()
{
   char Data_in;
   UART_Init();
   while(1)
   {
       Data_in = UART_RxChar(); /* receive char serially */
       if(Data_in == 'F')
       {
           motrf=1;
           motrb=0;
           motlf=1;
           motlb=0;
       }
       else if(Data_in == 'B')
       {
           motrf=0;
           motrb=1;
           motlf=0;
           motlb=1;
       }
       else if(Data_in == 'R')
       {
           motrf=0;
           motrb=1;
           motlf=1;
           motlb=0;
       }
       else if(Data_in == 'L')
       {
           motrf=1;
           motrb=0;
           motlf=0;
           motlb=1;
       }
       else if(Data_in == 'S')
       {
           motrf=0;
           motrb=0;
           motlf=0;
           motlb=0;
       }
   }
}
void UART_Init()
{
   TMOD = 0x20;
   TH1 = 0xFD;
   SCON = 0x50;
   TR1 = 1; 
}
char UART_RxChar()
{
   char dat;
   while (RI==0);
   RI = 0;
   dat = SBUF; 
   return(dat);
}