Using I/O Ports

Toggles all the 8051 ports ( P0, P1, P2 and P3 ) on/off and generates a square wave with a period of 2 milliseconds ( 500 Hertz ).

Code Example

main()
{
	serinit(19200);
	/* Infinite Loop */
	for( ;; )	
	{
		/* Reset all the ports */
		P0 = 0;
		P1 = 0;
		P2 = 0;
		P3 = 0;
	
		/* Delay 1 millisecond */
		delay(1);
			
		/* Set all the ports */
		P0 = 0xFF;
		P1 = 0xFF;
		P2 = 0xFF;
		P3 = 0xFF;
		
		/* Delay 1 millisecond */
		delay(1);
	}
}