diff --git a/main.c b/main.c
index 11d3230..10da389 100644
--- a/main.c
+++ b/main.c
@@ -108,7 +108,7 @@ int _write(int file, char *ptr, int len)
 
 	if (file == STDOUT_FILENO || file == STDERR_FILENO) {
 		for (i = 0; i < len; i++) {
-			if (ptr[i] == '\r' || ptr[i] == '\n') { // send CR+LF newline for any carriage return and line feed combination
+			if (ptr[i] == '\r' || ptr[i] == '\n') { // send CR+LF newline for most carriage return and line feed combination
 				if (newline==0 || (newline==ptr[i])) { // newline has already been detected
 					usart_putchar_nonblocking('\r'); // send newline over USART
 					usart_putchar_nonblocking('\n'); // send newline over USART
@@ -116,8 +116,11 @@ int _write(int file, char *ptr, int len)
 					cdcacm_putchar('\n'); // send newline over USB
 					newline = ptr[i]; // remember the newline
 				}
+				if (ptr[i] == '\n') { // line feed are always considered to end a line (the LF+CR combination is not supported to better support the others)
+					newline = 0; // clear new line
+				}
 			} else { // non-newline character
-					usart_putchar_nonblocking(ptr[i]); // send byte over USART
+				usart_putchar_nonblocking(ptr[i]); // send byte over USART
 				cdcacm_putchar(ptr[i]); // send byte over USB
 				newline = 0; // clear new line
 			}
@@ -424,6 +427,10 @@ int main(void)
 		printf("/!\\ RTC oscillator is disabled: the battery may be empty\n");
 	}
 
+	// variables to measure the RTC drift
+	uint32_t rtc_internal_start = rtc_get_counter_val();
+	uint32_t rtc_external_start = rtc_ticks;
+
 	// get date and time
 	printf("current time: %02lu:%02lu:%02lu\n", rtc_get_counter_val()/ticks_hour, (rtc_get_counter_val()%ticks_hour)/ticks_minute, (rtc_get_counter_val()%ticks_minute)/ticks_second); // display time
 	clock_animate_time(rtc_get_counter_val()); // set time with animation
@@ -484,6 +491,7 @@ int main(void)
 			}
 			if ((rtc_ticks%ticks_minute)==0) { // one minute passed
 				printf("%02lu:%02lu:%02lu\n", rtc_get_counter_val()/ticks_hour, (rtc_get_counter_val()%ticks_hour)/ticks_minute, (rtc_get_counter_val()%ticks_minute)/ticks_second); // display time
+				printf("internal RTC drift: %f%%\n", 1-((double)(rtc_ticks-rtc_external_start))/(double)(rtc_get_counter_val()-rtc_internal_start));
 			}
 			if ((rtc_ticks%ticks_hour)==0) { // one hours passed
 				clock_hours(); // show hour markers