diff --git a/module01/ex03/Makefile b/module01/ex03/Makefile
new file mode 100644
index 0000000..2e40cba
--- /dev/null
+++ b/module01/ex03/Makefile
@@ -0,0 +1 @@
+include ../../Makefile
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diff --git a/module01/ex03/main.c b/module01/ex03/main.c
new file mode 100644
index 0000000..77d3636
--- /dev/null
+++ b/module01/ex03/main.c
@@ -0,0 +1,94 @@
+#include <avr/io.h>
+
+// stringify
+#define STRINGIFY_HELPER(x)		#x
+#define STRINGIFY(x)			STRINGIFY_HELPER(x)
+
+// concatenate
+#define CONCAT_HELPER(x, y)		x ## y
+#define CONCAT(x, y)			CONCAT_HELPER(x, y)
+
+// get argument
+#define ARG_1(v1, v2)			v1
+#define ARG_2(v1, v2)			v2
+#define GET_PORT(args)			ARG_1 args
+#define GET_BIT(args)			ARG_2 args
+
+// actions on registers
+#define SET(register, bit)		register |= 1 << bit
+#define CLEAR(register, bit)	register &= ~(1 << bit)
+#define TEST(register, bit)		register & 1 << bit
+#define TOGGLE(register, bit)	register ^= 1 << bit
+
+// actions on elements
+#define SET_ELEM(elem)			SET(CONCAT(PORT, GET_PORT(elem)), GET_BIT(elem))
+#define CLEAR_ELEM(elem)		CLEAR(CONCAT(PORT, GET_PORT(elem)), GET_BIT(elem))
+#define TEST_ELEM(elem)			TEST(CONCAT(PORT, GET_PORT(elem)), GET_BIT(elem))
+#define TOGGLE_ELEM(elem)		TOGGLE(CONCAT(PORT, GET_PORT(elem)), GET_BIT(elem))
+#define MODE_OUTPUT(elem)		SET(CONCAT(DDR, GET_PORT(elem)), GET_BIT(elem))
+#define MODE_INPUT(elem)		CLEAR(CONCAT(DDR, GET_PORT(elem)), GET_BIT(elem))
+#define TOGGLE_PIN(elem)		SET(CONCAT(PIN, GET_PORT(elem)), GET_BIT(elem))
+#define TEST_PIN(elem)			(TEST(CONCAT(PIN, GET_PORT(elem)), GET_BIT(elem)))
+#define IS_PIN_SET(elem)		(TEST_PIN(elem) == 0)
+#define IS_PIN_CLEAR(elem)		(TEST_PIN(elem) == 1)
+
+// bits
+#define D1	0
+#define D2	1
+#define D3	2
+#define D4	4
+#define SW1	2
+#define SW2	4
+
+// elements (port, bit)
+#define LED1	(B, D1)
+#define LED2	(B, D2)
+#define LED3	(B, D3)
+#define LED4	(B, D4)
+#define BUTTON1	(D, SW1)
+#define BUTTON2	(D, SW2)
+
+// TIME
+#define PRESCALE_VALUE				1024
+#if (PRESCALE_VALUE == 1)
+	#define PRESCALE_SET			(1 << CS10)
+#elif (PRESCALE_VALUE == 8)
+	#define PRESCALE_SET			(1 << CS11)
+#elif (PRESCALE_VALUE == 64)
+	#define PRESCALE_SET			(1 << CS10) | (1 << CS11)
+#elif (PRESCALE_VALUE == 256)
+	#define PRESCALE_SET			(1 << CS12)
+#elif (PRESCALE_VALUE == 1024)
+	#define PRESCALE_SET			(1 << CS10) | (1 << CS12)
+#endif
+#define TIME_MS(ms)					(((F_CPU / PRESCALE_VALUE) * ms) / 1000)
+#define PERIOD						1000
+#define DUTY_CYCLE					10
+
+// END MACROS
+
+
+int main() {
+	MODE_OUTPUT(LED2);
+
+	// Table 16-4 : set timer in Fast PWM (Pulse With Modulation) mode with TOP = ICR1 (Mode 14)
+    SET(TCCR1A, WGM11);
+	SET(TCCR1B, WGM12);
+    SET(TCCR1B, WGM13);
+
+	// Table 16-2 : non-inverting mode, the LED will be ON for DUTY_CYCLE% of the time (CLEAR OC1A on compare match, SET OC1A at BOTTOM)
+	SET(TCCR1A, COM1A1);
+
+    // Table 16-4 : set the period (compare TOP value)
+    ICR1 = TIME_MS(PERIOD);
+    
+    // 16.9.3 : set the duty cycle to DUTY_CYCLE% of the time -> OC1A (alternate function of PORTB1, aka LED2) is cleared when TCNT1 (the counter value) equals OCR1A
+    OCR1A = TIME_MS(DUTY_CYCLE);
+
+    // start the timer with the prescaler
+    TCCR1B |= (PRESCALE_SET);
+
+	while(1) {
+		continue;
+	}
+}
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