diff --git a/module01/ex02/main.c b/module01/ex02/main.c
index 2a60ece..77d3636 100644
--- a/module01/ex02/main.c
+++ b/module01/ex02/main.c
@@ -1,36 +1,36 @@
 #include <avr/io.h>
 
 // stringify
-#define STRINGIFY_HELPER(x)			#x
-#define STRINGIFY(x)				STRINGIFY_HELPER(x)
+#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)
+#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
+#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
+#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)
+#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
@@ -76,13 +76,13 @@ int main() {
 	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)
+	// 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);
 
-    // set the period (compare TOP value)
+    // Table 16-4 : set the period (compare TOP value)
     ICR1 = TIME_MS(PERIOD);
     
-    // set the duty cycle to DUTY_CYCLE% of the time
+    // 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