use DCF77 to update time at boot and every hour

main.c

@@ -439,7 +439,7 @@ int main(void)
 	nvic_enable_irq(NVIC_RTC_IRQ); // allow the RTC to interrupt
 #endif
 	rtc_dcf77_setup(); // setup DCF77 module
-	rtc_dcf77_on(); // switch on DCF77 module
+	rtc_dcf77_on(); // switch on DCF77 module to get correct time
 	printf("OK\n");
 
 	// setup WS2812b LEDs
@@ -564,6 +564,7 @@ int main(void)
 				rtc_set_counter_val(ticks_time); // set new time to internal RTC
 #endif
 				printf("DCF77 time: 20%02u-%02u-%02u %02u:%02u:00\n", dcf77_time[5], dcf77_time[4], dcf77_time[2], dcf77_time[1], dcf77_time[0]); // display time
+				rtc_dcf77_off(); // switch DCF77 off since we have correct time
 			} else {
 				printf("DCF77 time: error\n");
 			}
@@ -588,6 +589,7 @@ int main(void)
 				printf("%02lu:%02lu:%02lu\n", ticks_time/ticks_hour, (ticks_time%ticks_hour)/ticks_minute, (ticks_time%ticks_minute)/ticks_second); // display external time
 			}
 			if ((ticks_time%ticks_hour)==0) { // one hours passed
+				rtc_dcf77_on(); // switch DCF77 on to update/correct time
 				clock_hours(); // show hour markers
 			}
 			if (ticks_time>=ticks_midday*2) { // one day passed