title: need help configuring port to input in 8051
body: <p>The connection is as follows  An infrared sensor circuit which yields 0 or 5v depending on   closed or open circuit output  line to port 2_0 pin of microcontroller 8051 philips.Problem        is when i do this the circuit value are overridden by the current value on port 2_0 led   always goes on.Here is my code(in keil c) i guess i have not configured P 2_0 as input properly   </p>
  
  <pre><code>void MSDelay(unsigned int);
  
  sbit led=P1^0;
  
  void main()
  {
      unsigned int var;
      P2=0xFF;
      TMOD=0x20;
      TH1=0xFD;
      SCON =0x50;
      TR1=1;
  
      while(1)
      {
          var=P2^0;
          if(var==0)
          {  
               led=1;
               SBUF='0';
               while(TI==0);
               TI=0;
               MSDelay(250);
          } 
          else
          {   
              led=0;
              SBUF='9';
              while(TI==0);
              TI=0;
              MSDelay(100);
          }
      }       
  }
  </code></pre>
  
  <p>EDIT : I was facing a problem since the 8086 processor i was using had a fault in it. Would recommend anyone trying this to get a few spares when programming.</p>