#include "io68hc11.h"

#define OPTION	MB(0x1039)
#define ADCTL	MB(0x1030)
#define PORTB	MB(0x1004)
#define ADR1	MB(0x1031)

void read_ad(void) {
	ADCTL=_00010000; //SCAN=0,MULT=1,AN[0:3]

	while (!(ADCTL&0x80)); //wait for CCF=1
}

int main(void) {
	OPTION=OPTION|0x80; //ADPU=1
	PORTB=0; //turn off LED
	while (1) {
		read_ad();
		if (ADR1>=128) { //checks if conversion result=1
			PORTB=PORTB|1; //turn on LED
		} else {
			PORTB=PORTB&~1; //turn off LED
		}
	}

	return 0;
}