diff --git a/main.c b/main.c
index 762ed78..1044db3 100644
--- a/main.c
+++ b/main.c
@@ -1,5 +1,7 @@
 #include <avr/io.h>
+#include <avr/interrupt.h>
 #include <util/delay.h>
+#include <stdio.h>
 #include "serial.h"
 #include "pins.h"
 
@@ -15,14 +17,21 @@ int main(){
 }
 
 void prepare(){
+	// enable global interrupts and serial port
+	sei();
 	serial_init(9600);
+
+	// digital input/output example
 	/*pin_mode(11, OUTPUT);
 	pin_mode(10, INPUT);
 	pin_mode(8, INPUT);*/
+
+	// anlog input example
 	pin_mode(A4, INPUT);
 }
 
 void loop(){
+	// digital input/output example
 	/*if(digital_read(10) && digital_read(8)){
 		digital_write(11, HIGH);
 	}
@@ -30,12 +39,11 @@ void loop(){
 		digital_write(11, LOW);
 	}*/
 
-	if(analog_read(A4) > 0){
-		serial_write("ok", 3);
-	}
-	else{
-		serial_write("nope", 5);
-	}
-	
+	// anlog input example
+	int analog = analog_read(A4);
+	char out[15];
+	sprintf(out, "%d", analog);
+	serial_write(out, 15);
+
 	_delay_ms(25);
 }
diff --git a/pins.c b/pins.c
index 39f1a4b..a116068 100644
--- a/pins.c
+++ b/pins.c
@@ -1,5 +1,6 @@
 #include "pins.h"
 #include <avr/io.h>
+#include <avr/interrupt.h>
 
 const unsigned char LOW = 0x00;
 const unsigned char HIGH = 0x01;
@@ -16,6 +17,9 @@ const unsigned char A5 = 0x13;
 const unsigned char A6 = 0x14;
 const unsigned char A7 = 0x15;
 
+double dutyCycle = 0; // TODO more than one???
+
+void analog_read_duty_cycle();
 unsigned char map_analog_pin(unsigned char);
 
 void pin_mode(unsigned char pin, unsigned char mode){
@@ -61,8 +65,6 @@ int digital_read(unsigned char pin){
 		return 0;
 	}
 
-	// TODO turn off pwm
-
 	if(pin < 8){
 		// pin 0-7
 		return PIND&_BV(pin) ? 1 : 0;
@@ -78,8 +80,6 @@ void digital_write(unsigned char pin, unsigned char value){
 		return;
 	}
 
-	// TODO turn off pwm
-
 	if(pin < 8){
 		// pin 0-7
 		if(value == HIGH){
@@ -102,31 +102,35 @@ void digital_write(unsigned char pin, unsigned char value){
 	}
 }
 
-int analog_read(unsigned char pin){
+unsigned int analog_read(unsigned char pin){
 	pin = map_analog_pin(pin);
 
 	if(pin > 7){
 		return 0;
 	}
 
-	// TODO use ADC
-
-	ADMUX = 0xf0|pin;
-	ADCSRA |= _BV(pin);
-	while(ADCSRA&_BV(pin));
+	// enable ADC (128 bit ADPS scaling factor 0x07),
+	// disable digital input buffer (DIDR0)
+	ADCSRA = _BV(ADEN)|_BV(ADIE)|0x07;
+	ADMUX = _BV(REFS0)|pin;
+	DIDR0 |= _BV(pin);
+//	while(!(ADCSRA&_BV(ADIF)));
+	analog_read_duty_cycle();
 
 	return ADC;
 }
 
-void analog_write(unsigned char pin, int value){
+void analog_read_duty_cycle(){
+	ADCSRA |= _BV(ADSC);
+}
+
+void analog_write(unsigned char pin, unsigned int value){
 	pin = map_analog_pin(pin);
 
 	if(pin > 7){
 		return;
 	}
 
-	// TODO turn off pwm
-
 	if(value == HIGH){
 		PORTC |= _BV(pin);
 	}
@@ -143,3 +147,8 @@ unsigned char map_analog_pin(unsigned char pin){
 
 	return pin;
 }
+
+ISR(ADC_vect){
+	dutyCycle = ADC;
+	analog_read_duty_cycle();
+}
diff --git a/pins.h b/pins.h
index 849fe71..a70fa85 100644
--- a/pins.h
+++ b/pins.h
@@ -18,7 +18,7 @@ extern const unsigned char A7;
 void pin_mode(unsigned char, unsigned char);
 int digital_read(unsigned char);
 void digital_write(unsigned char, unsigned char);
-int analog_read(unsigned char);
-void analog_write(unsigned char, int);
+unsigned int analog_read(unsigned char);
+void analog_write(unsigned char, unsigned int);
 
 #endif