diff --git a/lib/rtc_dcf77.c b/lib/rtc_dcf77.c
index 856aecb..6352e80 100644
--- a/lib/rtc_dcf77.c
+++ b/lib/rtc_dcf77.c
@@ -120,7 +120,7 @@ uint8_t* rtc_dcf77_time(void)
 	return to_return;
 }
 
-/** @brief interrupt service routine called when signal edge is detected */
+/** @brief interrupt service routine called when signal edge is detected, decoding the received DCF77 frame (composed by high pulses) */
 void RTC_DCF77_SIGNAL_ISR(void)
 {
 	exti_reset_request(RTC_DCF77_SIGNAL_EXTI); // reset interrupt