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define port P0 and define Pin1 P0^0

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define statement is use for constant value

#define TRUE 1
#define FALSE 0


what is difference between define port P0 and define Pin1 P0^0 ?

Code: 
#include <reg51.h>

#define port P0 

#define Pin1  P0^0  
#define Pin2  P0^1  
#define Pin3  P0^2 
#define Pin4  P0^3  

char value(void)
{
   unsigned char value;
   
   char i;
   
   for (i=0; i<4; i++)
	   
	   {
		  value = 0x1110 1111;
                  if(!Pin1) valueReturn = A;
                  if(!Pin2) valueReturn = B;
                  if(!Pin3) valueReturn = C;
                  if(!Pin4) valueReturn = D;
            
                  value <<= 1;
         
		  value ++;    
       }        
    return valueReturn;
}
 

what is difference between define port P0 and define Pin1 P0^0 ?
Click to expand...

The P0 statement represents a byte that maps all 8 pins of the port P0, whereas P0^0 represents a bit ( actualy the pin 0 of the port P0 ).
 
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    vead

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if (a != 0)
mean's 'if a is not equal to zero'.

what is meaning of if(!Pin1)
 

Different functions:

  • ! NOT opperator ( logic inverse of the variable at right side )
  • != inequality evaluation ( returns true if both sides are different )
 

andre_teprom said:
Different functions:

  • ! NOT opperator ( logic inverse of the variable at right side )
  • != inequality evaluation ( returns true if both sides are different )
Click to expand...

I know that but I don't understand if(!Pin1) in program
 

vead said:
I know that but I don't understand if(!Pin1) in program
Click to expand...

Code: 
if ([I]condition_is_true[/I])
   {
   do_this();
   }
else
   {
   do_that();
   }
Were:
  • condition_is_true => !Pin1
The above condition is true when Pin1==0
 
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