#include <stdbool.h>

__sfr __at(0xb0) P3;

__sfr __at(0x88) TCON;

__sfr __at(0x89) TMOD;

__sfr __at(0x8a) TL0;

__sfr __at(0x8c) TH0;

__sfr __at(0xa8) IE;

volatile unsigned long int clocktime;

volatile _Bool clockupdate;

void clockinc(void) __interrupt(1)

{

	TH0 = (65536 - 922) / 256;

	TL0 = (65536 - 922) % 256;

	clocktime++;

	clockupdate = true;

}

unsigned long int clock(void)

{

	unsigned long int ctmp;

	do

	{

		clockupdate = false;

		ctmp = clocktime;

	} while (clockupdate);

	return(ctmp);

}

void main(void)

{

	// Configure timer for 11.0592 Mhz default SYSCLK

	// 1000 ticks per second

	TH0 = (65536 - 922) / 256;

	TL0 = (65536 - 922) % 256;

	TMOD = 0x01;

	IE |= 0x82;

	TCON |= 0x10; // Start timer

	for(;;)

		P3 = ~(clock() / 1000) & 0x03;

}

sdcc-sdcc led.c

sdcc-packihx led.ihx > led.hex