diff --git a/module01/ex01/main.c b/module01/ex01/main.c
index 22b351c..26dc663 100644
--- a/module01/ex01/main.c
+++ b/module01/ex01/main.c
@@ -5,6 +5,7 @@
 #include "timer.h"
 
 #define PERIOD						500
+#define PRESCALE_VALUE				1024		// can be 1, 8, 64, 256, 1024
 
 // led turns on and off every PERIOD ms using CTC timer
 int main() {
@@ -14,7 +15,7 @@ int main() {
 
 	TCCR1A |= (1 << COM1A0);					// 14.3.1 : set Compare Output with COM1A0, it toggles OC1A on compare match (Table 16-1), OC1A is alternate function for PORTB1 (Table 14-3)
 
-	OCR1A = TIME_MS(PERIOD);					// Table 16-4 : set CTC compare value on channel A, the counter is cleared to zero when the counter value (TCNT1) matches the OCR1A register
+	OCR1A = TIME_MS(PERIOD, PRESCALE_VALUE);	// Table 16-4 : set CTC compare value on channel A, the counter is cleared to zero when the counter value (TCNT1) matches the OCR1A register
 
 	TCCR1B |= (PRESCALE_SET(PRESCALE_VALUE));
 
diff --git a/module01/ex01/timer.h b/module01/ex01/timer.h
index 3cb618e..c9d5f0e 100644
--- a/module01/ex01/timer.h
+++ b/module01/ex01/timer.h
@@ -1,7 +1,6 @@
 #ifndef TIMER_H
 #define TIMER_H
 
-#define PRESCALE_VALUE				1024		// can be 1, 8, 64, 256, 1024
 // table 16-5 : prescale sets
 #define PRESCALE_SET(value)  \
 									((value) == 1   ? (0<<CS12 | 0<<CS11 | 1<<CS10) : \
@@ -10,6 +9,6 @@
 									 (value) == 256 ? (1<<CS12 | 0<<CS11 | 0<<CS10) : \
 									 (value) == 1024? (1<<CS12 | 0<<CS11 | 1<<CS10) : \
 													  (0<<CS12 | 0<<CS11 | 0<<CS10))
-#define TIME_MS(ms)					(((F_CPU / PRESCALE_VALUE) * ms) / 1000)
+#define TIME_MS(ms, prescale_value)	(((F_CPU / prescale_value) * ms) / 1000)
 
 #endif // TIMER_H
\ No newline at end of file
diff --git a/module01/ex02/main.c b/module01/ex02/main.c
index ad9d808..ea5245d 100644
--- a/module01/ex02/main.c
+++ b/module01/ex02/main.c
@@ -5,23 +5,24 @@
 #include "timer.h"
 
 #define PERIOD						1000
+#define PRESCALE_VALUE				1024		                    // can be 1, 8, 64, 256, 1024
 #define DUTY_CYCLE					10
 
 // turns on led2 at 1Hz and duty cycle of 10%, not using PORTx, with empty infinite loop
 int main() {
 	MODE_OUTPUT(LED2);
 
-    SET(TCCR1A, WGM11);								// Table 16-4 : set timer in Fast PWM (Pulse With Modulation) mode with TOP = ICR1 (Mode 14)
+    SET(TCCR1A, WGM11);							                	// Table 16-4 : set timer in Fast PWM (Pulse With Modulation) mode with TOP = ICR1 (Mode 14)
 	SET(TCCR1B, WGM12);
     SET(TCCR1B, WGM13);
 
-	SET(TCCR1A, COM1A1);							// 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 16-2 : non-inverting mode, the LED will be ON for DUTY_CYCLE% of the time (CLEAR OC1A on compare match, SET OC1A at BOTTOM)
 
-    ICR1 = TIME_MS(PERIOD);							// Table 16-4 : set the period (compare TOP value)
+    ICR1 = TIME_MS(PERIOD, PRESCALE_VALUE);		                	// Table 16-4 : set the period (compare TOP value)
     
-    OCR1A = TIME_MS(PERCENT(DUTY_CYCLE, PERIOD));	// 16.9.3 : set the duty cycle to DUTY_CYCLE% of the time on channel A -> OC1A (alternate function of PORTB1, aka LED2) is cleared when TCNT1 (the counter value) equals OCR1A
+    OCR1A = TIME_MS(PERCENT(DUTY_CYCLE, PERIOD), PRESCALE_VALUE);	// 16.9.3 : set the duty cycle to DUTY_CYCLE% of the time on channel A -> OC1A (alternate function of PORTB1, aka LED2) is cleared when TCNT1 (the counter value) equals OCR1A
 
-    TCCR1B |= (PRESCALE_SET(PRESCALE_VALUE));		// start the timer with the prescaler
+    TCCR1B |= (PRESCALE_SET(PRESCALE_VALUE));	                	// start the timer with the prescaler
 
 	while(1);
 }
\ No newline at end of file
diff --git a/module01/ex02/timer.h b/module01/ex02/timer.h
index 3cb618e..c9d5f0e 100644
--- a/module01/ex02/timer.h
+++ b/module01/ex02/timer.h
@@ -1,7 +1,6 @@
 #ifndef TIMER_H
 #define TIMER_H
 
-#define PRESCALE_VALUE				1024		// can be 1, 8, 64, 256, 1024
 // table 16-5 : prescale sets
 #define PRESCALE_SET(value)  \
 									((value) == 1   ? (0<<CS12 | 0<<CS11 | 1<<CS10) : \
@@ -10,6 +9,6 @@
 									 (value) == 256 ? (1<<CS12 | 0<<CS11 | 0<<CS10) : \
 									 (value) == 1024? (1<<CS12 | 0<<CS11 | 1<<CS10) : \
 													  (0<<CS12 | 0<<CS11 | 0<<CS10))
-#define TIME_MS(ms)					(((F_CPU / PRESCALE_VALUE) * ms) / 1000)
+#define TIME_MS(ms, prescale_value)	(((F_CPU / prescale_value) * ms) / 1000)
 
 #endif // TIMER_H
\ No newline at end of file
diff --git a/module01/ex03/main.c b/module01/ex03/main.c
index 05d5f8f..00186fa 100644
--- a/module01/ex03/main.c
+++ b/module01/ex03/main.c
@@ -5,8 +5,9 @@
 #include "bitmanip.h"
 #include "timer.h"
 
-#define PERIOD						1000
-#define DUTY_CYCLE					10
+#define PERIOD							1000
+#define PRESCALE_VALUE					1024		// can be 1, 8, 64, 256, 1024
+#define DUTY_CYCLE						10
 
 // Table 16-4 : Waveform Generation Mode Bit Description
 #define CTC_TOP_OCR1A_IN_TCCR1B			(0<<WGM13 | 1<<WGM12)
@@ -31,7 +32,7 @@ void increment_duty_cycle(void *param) {
 	if(params->duty_cycle < params->max) {
 		params->duty_cycle += 10;
 	}
-	OCR1A = TIME_MS(PERCENT(params->duty_cycle, PERIOD));
+	OCR1A = TIME_MS(PERCENT(params->duty_cycle, PERIOD), PRESCALE_VALUE);
 }
 
 void decrement_duty_cycle(void *param) {
@@ -39,7 +40,7 @@ void decrement_duty_cycle(void *param) {
 	if(params->duty_cycle > params->min) {
 		params->duty_cycle -= 10;
 	}
-	OCR1A = TIME_MS(PERCENT(params->duty_cycle, PERIOD));
+	OCR1A = TIME_MS(PERCENT(params->duty_cycle, PERIOD), PRESCALE_VALUE);
 }
 
 void on_press(int bit, void (*action)(void*), void *params) {
@@ -62,16 +63,16 @@ int main() {
 
 	MODE_OUTPUT(LED2);
 
-    TCCR1A |= FAST_PWM_TOP_ICR1_IN_TCCR1A;				// Table 16-4 : set timer in Fast PWM (Pulse With Modulation) mode with TOP = ICR1 (Mode 14)
+    TCCR1A |= FAST_PWM_TOP_ICR1_IN_TCCR1A;							// Table 16-4 : set timer in Fast PWM (Pulse With Modulation) mode with TOP = ICR1 (Mode 14)
 	TCCR1B |= FAST_PWM_TOP_ICR1_IN_TCCR1B;
 
-	SET(TCCR1A, COM1A1);								// 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 16-2 : non-inverting mode, the LED will be ON for DUTY_CYCLE% of the time (CLEAR OC1A on compare match, SET OC1A at BOTTOM)
 
-    ICR1 = TIME_MS(PERIOD);								// Table 16-4 : set the period (compare TOP value)
+    ICR1 = TIME_MS(PERIOD, PRESCALE_VALUE);							// Table 16-4 : set the period (compare TOP value)
     
-    OCR1A = TIME_MS(PERCENT(DUTY_CYCLE, PERIOD));		// 16.9.3 : set the duty cycle to DUTY_CYCLE% of the time in channel A -> OC1A (alternate function of PORTB1, aka LED2) is cleared when TCNT1 (the counter value) equals OCR1A
+    OCR1A = TIME_MS(PERCENT(DUTY_CYCLE, PERIOD), PRESCALE_VALUE);	// 16.9.3 : set the duty cycle to DUTY_CYCLE% of the time in channel A -> OC1A (alternate function of PORTB1, aka LED2) is cleared when TCNT1 (the counter value) equals OCR1A
 
-    TCCR1B |= (PRESCALE_SET(PRESCALE_VALUE));			// start the timer with the prescaler
+    TCCR1B |= (PRESCALE_SET(PRESCALE_VALUE));						// start the timer with the prescaler
 
 	while(1) {
 		on_press(SW1, increment_duty_cycle, &params);
diff --git a/module01/ex03/timer.h b/module01/ex03/timer.h
index 3cb618e..c9d5f0e 100644
--- a/module01/ex03/timer.h
+++ b/module01/ex03/timer.h
@@ -1,7 +1,6 @@
 #ifndef TIMER_H
 #define TIMER_H
 
-#define PRESCALE_VALUE				1024		// can be 1, 8, 64, 256, 1024
 // table 16-5 : prescale sets
 #define PRESCALE_SET(value)  \
 									((value) == 1   ? (0<<CS12 | 0<<CS11 | 1<<CS10) : \
@@ -10,6 +9,6 @@
 									 (value) == 256 ? (1<<CS12 | 0<<CS11 | 0<<CS10) : \
 									 (value) == 1024? (1<<CS12 | 0<<CS11 | 1<<CS10) : \
 													  (0<<CS12 | 0<<CS11 | 0<<CS10))
-#define TIME_MS(ms)					(((F_CPU / PRESCALE_VALUE) * ms) / 1000)
+#define TIME_MS(ms, prescale_value)	(((F_CPU / prescale_value) * ms) / 1000)
 
 #endif // TIMER_H
\ No newline at end of file