8051 read write port

**Admin** Wed Jul 31, 2013 2:08 am

This example shows how to read 8-bit port 1 and copy the same value to port 3

/* 8051 header file*/
#include<reg51.h>

sfr P1 = 0x90; /* SFR definition for Port 1 */
sfr P3 = 0xB0; /* SFR definition for Port 3 */

/*------------------------------------------------
MAIN C Function
------------------------------------------------*/
void main (void)
{
unsigned char pval; /* temp variable for port values */

P1 = 0xFF; /* Setup P1 for Input */

/*--------------------------------------
Use the Toolbox buttons in the debugger
to change the value of P1. Open the
Port 1 and Port 3 dialogs from the
Peripherals Menu to view their status.
--------------------------------------*/
while (1)
{
pval = P1; /* Read P1 into pval */
P3 = pval; /* Write pval to P3 */
}
}