//CPU freq in kHz

#include <8052.h>
//CPU freq in kHz
#define F_CPU 3072

/* sleep_10ms is not very spot on, but good enough */
#define sleep_ms(__x) for(int __i = 0; __i < (__x * F_CPU - 60)/120; __i++);
#define sleep_10ms(x) for(int __j = 0; __j < (x * F_CPU - 60)/360; __j++)\
sleep_ms(x/10);

int main(void){
while(1){

P1 = 0xFF;
sleep_10ms(10);
P1 = 0x00;
sleep_10ms(10);
}
}