diff --git a/include/clockcontroller.h b/include/clockcontroller.h
new file mode 100644
index 00000000..c9748ce8
--- /dev/null
+++ b/include/clockcontroller.h
@@ -0,0 +1,15 @@
+#ifndef _CLOCKCONTROLLER_H
+#define _CLOCKCONTROLLER_H
+
+#include "globals.h"
+
+#ifdef HAS_IF482
+#include "if482.h"
+#elif defined HAS_DCF77
+#include "dcf77.h"
+#endif
+
+void clock_init(void);
+void clock_loop(void *pvParameters);
+
+#endif // _CLOCKCONTROLLER_H
\ No newline at end of file
diff --git a/include/dcf77.h b/include/dcf77.h
index cd06ea5a..f2693246 100644
--- a/include/dcf77.h
+++ b/include/dcf77.h
@@ -2,16 +2,12 @@
 #define _DCF77_H
 
 #include "globals.h"
-#include "rtctime.h"
 
 enum dcf_pulses { dcf_off, dcf_zero, dcf_one };
 enum dcf_pinstate { dcf_low, dcf_high };
 
-int dcf77_init(void);
-void dcf77_loop(void *pvParameters);
-void sendDCF77(void);
-void DCF_Out(uint8_t startsec);
-void generateTimeframe(time_t t);
+void DCF_Pulse(time_t startTime);
+void DCF77_Frame(time_t t);
 void set_DCF77_pin(dcf_pinstate state);
 uint8_t dec2bcd(uint8_t dec, uint8_t startpos, uint8_t endpos, uint8_t pArray[]);
 
diff --git a/include/globals.h b/include/globals.h
index fdca3b5e..753fb281 100644
--- a/include/globals.h
+++ b/include/globals.h
@@ -40,11 +40,17 @@
 #define SCREEN_MODE (0x80)
 
 // I2C bus access control
-#define I2C_MUTEX_LOCK()    xSemaphoreTake(I2Caccess, (3 * DISPLAYREFRESH_MS / portTICK_PERIOD_MS)) == pdTRUE
-#define I2C_MUTEX_UNLOCK()  xSemaphoreGive(I2Caccess)
+#define I2C_MUTEX_LOCK()                                                       \
+  xSemaphoreTake(I2Caccess, (3 * DISPLAYREFRESH_MS / portTICK_PERIOD_MS)) ==   \
+      pdTRUE
+#define I2C_MUTEX_UNLOCK() xSemaphoreGive(I2Caccess)
 
-// time pulse frequency 1Hz
-#define PPS (1000)
+// Clock controller settings
+#define PPS (1000) // on board time pulse frequency in ms
+#define IF482_FRAME_SIZE (17)
+#define IF482_PULSE_LENGTH (1000)
+#define DCF77_FRAME_SIZE (60)
+#define DCF77_PULSE_LENGTH (100)
 
 // Struct holding devices's runtime configuration
 typedef struct {
@@ -66,7 +72,8 @@ typedef struct {
   uint8_t runmode;       // 0=normal, 1=update
   uint8_t payloadmask;   // bitswitches for payload data
   char version[10];      // Firmware version
-  uint8_t bsecstate[BSEC_MAX_STATE_BLOB_SIZE + 1]; // BSEC state for BME680 sensor
+  uint8_t
+      bsecstate[BSEC_MAX_STATE_BLOB_SIZE + 1]; // BSEC state for BME680 sensor
 } configData_t;
 
 // Struct holding payload for data send queue
@@ -151,12 +158,4 @@ extern Timezone myTZ;
 #include "bme680mems.h"
 #endif
 
-#ifdef HAS_IF482
-#include "if482.h"
-#endif
-
-#ifdef HAS_DCF77
-#include "dcf77.h"
-#endif
-
 #endif
\ No newline at end of file
diff --git a/include/if482.h b/include/if482.h
index b38013d8..19f1f256 100644
--- a/include/if482.h
+++ b/include/if482.h
@@ -2,11 +2,12 @@
 #define _IF482_H
 
 #include "globals.h"
-#include "rtctime.h"
 
-int if482_init(void);
-void if482_loop(void *pvParameters);
-TickType_t tx_time(unsigned long baud, uint32_t config, int8_t rxPin,
+extern HardwareSerial IF482; 
+
+void IF482_Pulse(time_t t);
+String IF482_Frame(time_t tt);
+TickType_t tx_Ticks(unsigned long baud, uint32_t config, int8_t rxPin,
                    int8_t txPins);
 
 #endif
\ No newline at end of file
diff --git a/include/main.h b/include/main.h
index 4f4452b7..a3666baf 100644
--- a/include/main.h
+++ b/include/main.h
@@ -17,5 +17,5 @@
 #include "led.h"
 #include "spislave.h"
 #include "lorawan.h"
-
+#include "clockcontroller.h"
 #endif
\ No newline at end of file
diff --git a/include/rtctime.h b/include/rtctime.h
index 50f95539..8b617f45 100644
--- a/include/rtctime.h
+++ b/include/rtctime.h
@@ -24,6 +24,7 @@ float get_rtctemp(void);
 void IRAM_ATTR CLOCKIRQ();
 int timepulse_init(void);
 void timepulse_start();
-void sync_clock(void);
+int sync_TimePulse(void);
+int sync_SysTime(time_t);
 
 #endif // _RTCTIME_H
\ No newline at end of file
diff --git a/src/clockcontroller.cpp b/src/clockcontroller.cpp
new file mode 100644
index 00000000..91236213
--- /dev/null
+++ b/src/clockcontroller.cpp
@@ -0,0 +1,72 @@
+#include "clockcontroller.h"
+
+#if defined HAS_IF482 || defined HAS_DCF77
+
+#if defined HAS_DCF77 && defined HAS_IF482
+#error You must define at most one of IF482 or DCF77!
+#endif
+
+#if (PPS < IF482_PULSE_LENGTH) || (PPS < DCF77_PULSE_LENGTH)
+#error On board timepulse too fast for clockcontroller
+#endif
+
+// Local logging tag
+static const char TAG[] = "main";
+
+void clock_init(void) { // ClockTask
+
+  timepulse_init(); // setup timepulse
+
+// setup output interface
+#ifdef HAS_IF482
+  // initialize and configure IF482 Generator
+  IF482.begin(HAS_IF482);
+#elif defined HAS_DCF77
+  // initialize and configure DCF77 output
+  pinMode(HAS_DCF77, OUTPUT);
+  set_DCF77_pin(dcf_low);
+#endif
+
+  xTaskCreatePinnedToCore(clock_loop,  // task function
+                          "clockloop", // name of task
+                          2048,        // stack size of task
+                          (void *)1,   // task parameter
+                          4,           // priority of the task
+                          &ClockTask,  // task handle
+                          0);          // CPU core
+
+  assert(ClockTask); // has clock task started?
+  timepulse_start(); // start pulse
+} // clock_init
+
+void clock_loop(void *pvParameters) { // ClockTask
+
+  configASSERT(((uint32_t)pvParameters) == 1); // FreeRTOS check
+
+  TickType_t wakeTime, txDelay;
+  uint32_t pulseCycle;
+  void (*pTimeTx)(time_t); // pointer to time telegram output function
+
+#ifdef HAS_IF482
+  txDelay = pdMS_TO_TICKS(1000) - tx_Ticks(HAS_IF482);
+  pulseCycle = PPS / IF482_PULSE_LENGTH;
+  pTimeTx = IF482_Pulse;
+#elif defined HAS_DCF77
+  txDelay = pdMS_TO_TICKS(DCF77_PULSE_LENGTH);
+  pulseCycle = PPS / DCF77_PULSE_LENGTH;
+  pTimeTx = DCF_Pulse;
+#endif
+
+  // output time telegram triggered by timepulse
+  for (;;) {
+    if (timeStatus() == timeSet) // do we have valid time?
+      xTaskNotifyWait(0x00, ULONG_MAX, &wakeTime,
+                      portMAX_DELAY); // wait for timepulse
+    for (uint8_t i = 1; i <= pulseCycle; i++) {
+      pTimeTx(now());
+      vTaskDelayUntil(&wakeTime, txDelay);
+    }
+  } // for
+} // clock_loop()
+
+#endif // HAS_DCF77 || HAS_IF482
\ No newline at end of file
diff --git a/src/cyclic.cpp b/src/cyclic.cpp
index e20d2948..da42af4e 100644
--- a/src/cyclic.cpp
+++ b/src/cyclic.cpp
@@ -41,7 +41,8 @@ void doHousekeeping() {
   if ((millis() >= nextRTCTimeSync) && (timeStatus() == timeSet)) {
     nextRTCTimeSync = millis() + TIME_WRITE_INTERVAL_RTC *
                                      60000; // set up next time sync period
-    if (!set_rtctime(now()))    // epoch time
+    sync_TimePulse();                       // wait for next start of second
+    if (!set_rtctime(now()))                // epoch time
       ESP_LOGE(TAG, "RTC set time failure");
     else
       ESP_LOGI(TAG, "RTC time updated");
diff --git a/src/dcf77.cpp b/src/dcf77.cpp
index 4ab18fca..f63965bf 100644
--- a/src/dcf77.cpp
+++ b/src/dcf77.cpp
@@ -8,76 +8,41 @@ https://www-user.tu-chemnitz.de/~heha/viewzip.cgi/hs/Funkuhr.zip/
 
 #ifdef HAS_DCF77
 
-#ifdef IF_482
-#error You must define at most one of IF482 or DCF77!
-#endif
-
 #include "dcf77.h"
 
 // Local logging tag
 static const char TAG[] = "main";
 
-bool volatile BitsPending = false;
-
-#define DCF77_FRAME_SIZE (60)
-#define DCF77_PULSE_DURATION (100)
-
 // array of dcf pulses for three minutes
-uint8_t DCFtimeframe[DCF77_FRAME_SIZE];
+uint8_t DCFpulse[DCF77_FRAME_SIZE];
 
-// initialize and configure DCF77 output
-int dcf77_init(void) {
+// called by timepulse interrupt to ticker out DCF signal
+void DCF_Pulse(time_t startTime) {
 
-  pinMode(HAS_DCF77, OUTPUT);
-  set_DCF77_pin(dcf_low);
-  timepulse_init(); // setup timepulse
-
-  xTaskCreatePinnedToCore(dcf77_loop,  // task function
-                          "dcf77loop", // name of task
-                          2048,        // stack size of task
-                          (void *)1,   // parameter of the task
-                          3,           // priority of the task
-                          &ClockTask,  // task handle
-                          0);          // CPU core
-
-  assert(ClockTask);      // has clock task started?
-  DCF_Out(second(now())); // sync DCF time on next second
-  timepulse_start();      // start pulse
-
-  return 1; // success
-} // ifdcf77_init
-
-// called every 100msec by hardware timer to pulse out DCF signal
-void DCF_Out(uint8_t startOffset_sec) {
-
-  static uint8_t bit = startOffset_sec;
+  static uint8_t current_second = second(startTime);
   static uint8_t pulse = 0;
-#ifdef TIME_SYNC_INTERVAL_DCF
-  static uint32_t nextDCFsync = millis() + TIME_SYNC_INTERVAL_DCF * 60000;
-#endif
+  static bool SecondsPending = false;
 
-  if (!BitsPending) {
-    // do we have confident time/date?
-    if ((timeStatus() == timeSet) || (timeStatus() == timeNeedsSync)) {
-      // prepare frame to send for next minute
-      generateTimeframe(now() + DCF77_FRAME_SIZE + 1);
-      // kick off output of telegram
-      BitsPending = true;
-    } else
-      return;
+  if (!SecondsPending) {
+    // prepare dcf timeframe to send for next minute
+    DCF77_Frame(now() + DCF77_FRAME_SIZE + 1);
+    ESP_LOGD(TAG, "DCF77 minute %d", minute(now() + DCF77_FRAME_SIZE + 1));
+    // begin output of dcf timeframe
+    SecondsPending = true;
   }
 
   // ticker out current DCF frame
-  if (BitsPending) {
+  if (SecondsPending) {
     switch (pulse++) {
 
     case 0: // start of second -> start of timeframe for logic signal
-      if (DCFtimeframe[bit] != dcf_off)
+      if (DCFpulse[current_second] != dcf_off)
         set_DCF77_pin(dcf_low);
+      ESP_LOGD(TAG, "DCF77 bit %d", current_second);
       break;
 
     case 1: // 100ms after start of second -> end of timeframe for logic 0
-      if (DCFtimeframe[bit] == dcf_zero)
+      if (DCFpulse[current_second] == dcf_zero)
         set_DCF77_pin(dcf_high);
       break;
 
@@ -87,53 +52,17 @@ void DCF_Out(uint8_t startOffset_sec) {
 
     case 9: // 900ms after start -> last pulse before next second starts
       pulse = 0;
-      if (bit++ == (DCF77_FRAME_SIZE - 1)) // end of DCF77 frame (59th second)
+      if (current_second++ >=
+          (DCF77_FRAME_SIZE - 1)) // end of DCF77 frame (59th second)
       {
-        bit = 0;
-        BitsPending = false;
-// recalibrate clock after a fixed timespan, do this in 59th second
-#ifdef TIME_SYNC_INTERVAL_DCF
-        if ((millis() >= nextDCFsync)) {
-          sync_clock(); // waiting for second 59
-          nextDCFsync = millis() + TIME_SYNC_INTERVAL_DCF *
-                                       60000; // set up next time sync period
-        }
-#endif
+        current_second = 0;
+        SecondsPending = false;
       };
       break;
 
     }; // switch
   };   // if
-} // DCF_Out()
-
-void dcf77_loop(void *pvParameters) {
-
-  configASSERT(((uint32_t)pvParameters) == 1); // FreeRTOS check
-
-  TickType_t wakeTime;
-
-  // task remains in blocked state until it is notified by isr
-  for (;;) {
-    xTaskNotifyWait(
-        0x00,           // don't clear any bits on entry
-        ULONG_MAX,      // clear all bits on exit
-        &wakeTime,      // receives moment of call from isr
-        portMAX_DELAY); // wait forever (missing error handling here...)
-
-    // select clock scale
-#if (PPS == DCF77_PULSE_DURATION) // we don't need clock rescaling
-    DCF_Out(0);
-#elif (PPS > DCF77_PULSE_DURATION) // we need upclocking
-    for (uint8_t i = 1; i <= PPS / DCF77_PULSE_DURATION; i++) {
-      DCF_Out(0);
-      vTaskDelayUntil(&wakeTime, pdMS_TO_TICKS(DCF77_PULSE_DURATION));
-    }
-#else // we need downclocking, not yet implemented
-#error Timepulse too fast for DCF77 emulator
-#endif
-
-  } // for
-} // dcf77_loop()
+} // DCF_Pulse()
 
 // helper function to convert decimal to bcd digit
 uint8_t dec2bcd(uint8_t dec, uint8_t startpos, uint8_t endpos,
@@ -151,40 +80,38 @@ uint8_t dec2bcd(uint8_t dec, uint8_t startpos, uint8_t endpos,
   return parity;
 }
 
-void generateTimeframe(time_t tt) {
+void DCF77_Frame(time_t tt) {
 
-  uint8_t ParityCount;
+  uint8_t Parity;
   time_t t = myTZ.toLocal(tt); // convert to local time
 
   // ENCODE HEAD
   // bits 0..19 initialized with zeros
   for (int n = 0; n <= 19; n++)
-    DCFtimeframe[n] = dcf_zero;
+    DCFpulse[n] = dcf_zero;
   // bits 17..18: adjust for DayLightSaving
-  DCFtimeframe[18 - (myTZ.locIsDST(t) ? 1 : 0)] = dcf_one;
+  DCFpulse[18 - (myTZ.locIsDST(t) ? 1 : 0)] = dcf_one;
   // bit 20: must be 1 to indicate time active
-  DCFtimeframe[20] = dcf_one;
+  DCFpulse[20] = dcf_one;
 
   // ENCODE MINUTE (bits 21..28)
-  ParityCount = dec2bcd(minute(t), 21, 27, DCFtimeframe);
-  DCFtimeframe[28] = (ParityCount & 1) ? dcf_one : dcf_zero;
+  Parity = dec2bcd(minute(t), 21, 27, DCFpulse);
+  DCFpulse[28] = (Parity & 1) ? dcf_one : dcf_zero;
 
   // ENCODE HOUR (bits 29..35)
-  ParityCount = dec2bcd(hour(t), 29, 34, DCFtimeframe);
-  DCFtimeframe[35] = (ParityCount & 1) ? dcf_one : dcf_zero;
+  Parity = dec2bcd(hour(t), 29, 34, DCFpulse);
+  DCFpulse[35] = (Parity & 1) ? dcf_one : dcf_zero;
 
   // ENCODE DATE (bits 36..58)
-  ParityCount = dec2bcd(day(t), 36, 41, DCFtimeframe);
-  ParityCount +=
-      dec2bcd((weekday(t) - 1) ? (weekday(t) - 1) : 7, 42, 44, DCFtimeframe);
-  ParityCount += dec2bcd(month(t), 45, 49, DCFtimeframe);
-  ParityCount +=
-      dec2bcd(year(t) - 2000, 50, 57,
-              DCFtimeframe); // yes, we have a millenium 3000 bug here ;-)
-  DCFtimeframe[58] = (ParityCount & 1) ? dcf_one : dcf_zero;
+  Parity = dec2bcd(day(t), 36, 41, DCFpulse);
+  Parity += dec2bcd((weekday(t) - 1) ? (weekday(t) - 1) : 7, 42, 44, DCFpulse);
+  Parity += dec2bcd(month(t), 45, 49, DCFpulse);
+  Parity += dec2bcd(year(t) - 2000, 50, 57,
+                    DCFpulse); // yes, we have a millenium 3000 bug here ;-)
+  DCFpulse[58] = (Parity & 1) ? dcf_one : dcf_zero;
 
   // ENCODE TAIL (bit 59)
-  DCFtimeframe[59] = dcf_off;
+  DCFpulse[59] = dcf_off;
   // !! missing code here for leap second !!
 
   /*
@@ -192,7 +119,7 @@ void generateTimeframe(time_t tt) {
     char out[DCF77_FRAME_SIZE + 1];
     uint8_t i;
     for (i = 0; i < DCF77_FRAME_SIZE; i++) {
-      out[i] = DCFtimeframe[i] + '0'; // convert int digit to printable ascii
+      out[i] = DCFpulse[i] + '0'; // convert int digit to printable ascii
     }
     out[DCF77_FRAME_SIZE] = '\0'; // string termination char
     ESP_LOGD(TAG, "DCF Timeframe = %s", out);
@@ -219,4 +146,6 @@ void set_DCF77_pin(dcf_pinstate state) {
   } // switch
 } // DCF77_pulse
 
+// helper function calculates next minute
+
 #endif // HAS_DCF77
\ No newline at end of file
diff --git a/src/display.cpp b/src/display.cpp
index 8ff2b83e..07afdebb 100644
--- a/src/display.cpp
+++ b/src/display.cpp
@@ -139,7 +139,7 @@ void refreshtheDisplay() {
       u8x8.setPowerSave(!cfg.screenon);
     }
 
-    // if display is switched off we don't refresh it and save time
+    // if display is switched off we don't refresh it to relax cpu
     if (!DisplayState)
       return;
 
@@ -220,7 +220,7 @@ void refreshtheDisplay() {
 #if (!defined HAS_DCF77) && (!defined HAS_IF482)
     // update LoRa status display (line 6)
     u8x8.printf("%-16s", display_line6);
-#else // we want a time display instead LoRa status
+#else // we want a systime display instead LoRa status
     time_t t = myTZ.toLocal(now());
     char timeState =
         (timeStatus() == timeSet) ? timesyncSymbol : timeNosyncSymbol;
diff --git a/src/gpsread.cpp b/src/gpsread.cpp
index 604216a5..622920b2 100644
--- a/src/gpsread.cpp
+++ b/src/gpsread.cpp
@@ -88,8 +88,8 @@ time_t tmConvert_t(uint16_t YYYY, uint8_t MM, uint8_t DD, uint8_t hh,
 
 // function to fetch current time from gps
 time_t get_gpstime(void) {
-  // !! never call now() in this function, this would break this function
-  // to be used as SyncProvider due to recursive call to now()
+  // !! never call now() or delay in this function, this would break this
+  // function to be used as SyncProvider for Time.h
 
   if ((gps.time.age() < 1500) && (gps.time.isValid())) {
     // get current gps time
@@ -98,9 +98,7 @@ time_t get_gpstime(void) {
                     gps.time.hour(), gps.time.minute(), gps.time.second());
     ESP_LOGD(TAG, "GPS time: %4d/%02d/%02d %02d:%02d:%02d", year(t), month(t),
              day(t), hour(t), minute(t), second(t));
-    // sync on top of next second by timepulse
-    sync_clock();
-    return t + 1;
+    return t;
   } else {
     ESP_LOGW(TAG, "GPS has no confident time");
     return 0; // sync failure, 0 effects calling SyncProvider() to not set time
diff --git a/src/if482.cpp b/src/if482.cpp
index a7fe5015..57ee66c5 100644
--- a/src/if482.cpp
+++ b/src/if482.cpp
@@ -79,46 +79,21 @@ not evaluated by model BU-190
 
 #ifdef HAS_IF482
 
-#ifdef HAS_DCF77
-#error You must define at most one of IF482 or DCF77!
-#endif
-
 #include "if482.h"
 
 // Local logging tag
 static const char TAG[] = "main";
 
-#define IF482_FRAME_SIZE (17)
-#define IF482_PULSE_DURATION (1000)
-
 HardwareSerial IF482(2); // use UART #2 (note: #1 may be in use for serial GPS)
 
-// initialize and configure IF482 Generator
-int if482_init(void) {
+// called by timepulse interrupt to ticker out DCF signal
+void IF482_Pulse(time_t startTime) {
+  IF482.print(IF482_Frame(startTime + 1)); // if482 telegram for next second
+}
 
-  // open serial interface
-  IF482.begin(HAS_IF482);
-  // setup timepulse
-  timepulse_init();
+String IF482_Frame(time_t startTime) {
 
-  // start if482 serial output feed task
-  xTaskCreatePinnedToCore(if482_loop,  // task function
-                          "if482loop", // name of task
-                          2048,        // stack size of task
-                          (void *)1,   // parameter of the task
-                          4,           // priority of the task
-                          &ClockTask,  // task handle
-                          0);          // CPU core
-
-  assert(ClockTask); // has clock task started?
-  // timepulse_start(); // start pulse
-
-  return 1; // success
-} // if482_init
-
-String IF482_Out(time_t tt) {
-
-  time_t t = myTZ.toLocal(tt);
+  time_t t = myTZ.toLocal(startTime);
   char mon, buf[14], out[IF482_FRAME_SIZE];
 
   switch (timeStatus()) { // indicates if time has been set and recently synced
@@ -134,7 +109,7 @@ String IF482_Out(time_t tt) {
   } // switch
 
   // do we have confident time/date?
-  if ((timeStatus() == timeSet) || (timeStatus() == timeNeedsSync))
+  if (timeStatus() == timeSet)
     snprintf(buf, sizeof(buf), "%02u%02u%02u%1u%02u%02u%02u", year(t) - 2000,
              month(t), day(t), weekday(t), hour(t), minute(t), second(t));
   else
@@ -146,62 +121,9 @@ String IF482_Out(time_t tt) {
   return out;
 }
 
-void if482_loop(void *pvParameters) {
-
-  configASSERT(((uint32_t)pvParameters) == 1); // FreeRTOS check
-
-  TickType_t wakeTime;
-  const TickType_t tTx = tx_time(HAS_IF482); // duration of telegram transmit
-
-  // phase 1: sync task on top of second
-
-  const TickType_t t0 = xTaskGetTickCount(); // moment of start top of second
-  sync_clock();                              // delay until top of second
-  timepulse_start();                         // start timepulse
-
-  xTaskNotifyWait(
-      0x00,           // don't clear any bits on entry
-      ULONG_MAX,      // clear all bits on exit
-      &wakeTime,      // receives moment of call from isr
-      portMAX_DELAY); // wait forever (missing error handling here...)
-
-  const TickType_t tOffset = wakeTime - t0;
-  const TickType_t tShot =
-      (tOffset < tTx) ? (1000 - tOffset - tTx) : (tOffset - tTx);
-
-  ESP_LOGI(TAG, "IF482 signal synced with clock, tShot=%dms", tShot);
-
-  // phase 2: sync task on time pulse interrupt
-  for (;;) {
-    xTaskNotifyWait(
-        0x00,           // don't clear any bits on entry
-        ULONG_MAX,      // clear all bits on exit
-        &wakeTime,      // receives moment of call from isr
-        portMAX_DELAY); // wait forever (missing error handling here...)
-
-// select clock scale
-#if (PPS == IF482_PULSE_DURATION) // we don't need clock rescaling
-    // wait until it's time to start transmit telegram for next second
-    vTaskDelayUntil(&wakeTime, tShot); // sets waketime to moment of tShot
-    IF482.print(IF482_Out(now() + 1));
-
-#elif (PPS > IF482_PULSE_DURATION) // we need upclocking
-    for (uint8_t i = 1; i <= PPS / IF482_PULSE_DURATION; i++) {
-      vTaskDelayUntil(&wakeTime, tShot); // sets waketime to moment of shot
-      IF482.print(IF482_Out(now() + 1));
-    }
-
-#else // we need downclocking, not yet implemented
-#error Timepulse too fast for IF482 generator
-#endif
-
-  } // forever
-
-} // if482_loop()
-
 // calculate serial tx time from IF482 serial settings
-TickType_t tx_time(unsigned long baud, uint32_t config, int8_t rxPin,
-                   int8_t txPins) {
+TickType_t tx_Ticks(unsigned long baud, uint32_t config, int8_t rxPin,
+                    int8_t txPins) {
 
   uint32_t datenbits = ((config & 0x0c) >> 2) + 5;
   uint32_t stopbits = ((config & 0x20) >> 5) + 1;
diff --git a/src/irqhandler.cpp b/src/irqhandler.cpp
index fbbf06fa..3f680702 100644
--- a/src/irqhandler.cpp
+++ b/src/irqhandler.cpp
@@ -16,7 +16,7 @@ void irqHandler(void *pvParameters) {
         0x00,             // Don't clear any bits on entry
         ULONG_MAX,        // Clear all bits on exit
         &InterruptStatus, // Receives the notification value
-        portMAX_DELAY);   // wait forever (missing error handling here...)
+        portMAX_DELAY);   // wait forever
 
 // button pressed?
 #ifdef HAS_BUTTON
diff --git a/src/lorawan.cpp b/src/lorawan.cpp
index edc0d630..b0ea74e0 100644
--- a/src/lorawan.cpp
+++ b/src/lorawan.cpp
@@ -6,7 +6,7 @@ static const char TAG[] = "lora";
 
 #ifdef HAS_LORA
 
-#if CLOCK_ERROR_PROCENTAGE > 7 
+#if CLOCK_ERROR_PROCENTAGE > 7
 #warning CLOCK_ERROR_PROCENTAGE value in lmic_config.h is too high; values > 7 will cause side effects
 #endif
 
@@ -408,7 +408,7 @@ void lora_enqueuedata(MessageBuffer_t *message, sendprio_t prio) {
   BaseType_t ret;
   switch (prio) {
   case prio_high:
-  ret = xQueueSendToFront(LoraSendQueue, (void *)message, (TickType_t)0);
+    ret = xQueueSendToFront(LoraSendQueue, (void *)message, (TickType_t)0);
     break;
   case prio_low:
   case prio_normal:
@@ -471,7 +471,8 @@ void user_request_network_time_callback(void *pVoidUserUTCTime,
   setTime(*pUserUTCTime);
   ESP_LOGI(TAG, "LoRaWAN network has set the system time");
 #ifdef HAS_RTC
-  if (!set_rtctime(*pUserUTCTime)) // epoch time
+  sync_TimePulse();                // wait for next start of second
+  if (!set_rtctime(*pUserUTCTime+1)) // epoch time
     ESP_LOGE(TAG, "RTC set time failure");
 #endif
 }
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index e0754d49..ff4625b0 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -338,6 +338,7 @@ void setup() {
 #ifdef HAS_RTC
   strcat_P(features, " RTC");
   assert(rtc_init());
+  sync_TimePulse();             // wait for next start of second
   setSyncProvider(get_rtctime); // sync time now and then
   if (timeStatus() != timeSet)
     ESP_LOGI(TAG, "Unable to sync system time with RTC");
@@ -416,6 +417,7 @@ void setup() {
 #endif // HAS_BUTTON
 
 #ifdef HAS_GPS
+  sync_TimePulse();             // wait for next start of second
   setSyncProvider(get_gpstime); // sync time now and then
   if (timeStatus() != timeSet)
     ESP_LOGI(TAG, "Unable to sync system time with GPS");
@@ -429,12 +431,9 @@ void setup() {
   setSyncInterval(TIME_SYNC_INTERVAL_GPS * 60);
 #endif
 
-#ifdef HAS_IF482
-  ESP_LOGI(TAG, "Starting IF482 Generator...");
-  assert(if482_init());
-#elif defined HAS_DCF77
-  ESP_LOGI(TAG, "Starting DCF77 Generator...");
-  assert(dcf77_init());
+#if defined HAS_IF482 || defined HAS_DCF77
+  ESP_LOGI(TAG, "Starting Clock Controller...");
+  clock_init();
 #endif
 
 } // setup()
diff --git a/src/paxcounter.conf b/src/paxcounter.conf
index 555a0491..1b215647 100644
--- a/src/paxcounter.conf
+++ b/src/paxcounter.conf
@@ -82,11 +82,10 @@
 #define RESPONSE_TIMEOUT_MS             60000   // firmware binary server connection timeout [milliseconds]
 
 // settings for syncing time of node and external time sources
-#define TIME_SYNC_INTERVAL_GPS          5       // sync time each .. minutes from source GPS [default = 5], comment out means off          
+#define TIME_SYNC_INTERVAL_GPS          5       // sync time each .. minutes from GPS [default = 5], comment out means off          
 #define TIME_SYNC_INTERVAL_RTC          60      // sync time each .. minutes from RTC [default = 60], comment out means off          
 #define TIME_WRITE_INTERVAL_RTC         60      // write time each .. minutes from GPS/LORA to RTC [default = 60], comment out means off          
 //#define TIME_SYNC_INTERVAL_LORA       60      // sync time each .. minutes from LORA network [default = 60], comment out means off
-#define TIME_SYNC_INTERVAL_DCF          60      // sync DCF signal time each .. minutes from internal time [default = 60], comment out means off    
 
 // time zone, see https://github.com/JChristensen/Timezone/blob/master/examples/WorldClock/WorldClock.ino
 #define DAYLIGHT_TIME                   {"CEST", Last, Sun, Mar, 2, 120}     // Central European Summer Time
diff --git a/src/rtctime.cpp b/src/rtctime.cpp
index d5e10163..f1ced44f 100644
--- a/src/rtctime.cpp
+++ b/src/rtctime.cpp
@@ -16,7 +16,7 @@ int timepulse_init() {
   // setup external interupt for active low RTC INT pin
   pinMode(GPS_INT, INPUT_PULLDOWN);
   // setup external rtc 1Hz clock as pulse per second clock
-  ESP_LOGI(TAG, "Time base: GPS timepulse");
+  ESP_LOGI(TAG, "Time base: external (GPS)");
   return 1; // success
 
 // use pulse from on board RTC chip as time base with fixed frequency
@@ -30,7 +30,7 @@ int timepulse_init() {
     Rtc.SetSquareWavePinClockFrequency(DS3231SquareWaveClock_1Hz);
     Rtc.SetSquareWavePin(DS3231SquareWavePin_ModeClock);
     I2C_MUTEX_UNLOCK();
-    ESP_LOGI(TAG, "Time base: external RTC timepulse");
+    ESP_LOGI(TAG, "Time base: external (RTC)");
     return 1; // success
   } else {
     ESP_LOGE(TAG, "I2c bus busy - RTC initialization error");
@@ -41,9 +41,9 @@ int timepulse_init() {
 #else
   // use ESP32 hardware timer as time base with adjustable frequency
   clockCycle = timerBegin(1, 8000, true); // set 80 MHz prescaler to 1/10000 sec
-  timerAttachInterrupt(clockCycle, &CLOCKIRQ, true);
+  //timerAttachInterrupt(clockCycle, &CLOCKIRQ, true);
   timerAlarmWrite(clockCycle, 10000, true); // 1000ms
-  ESP_LOGI(TAG, "Time base: ESP32 hardware timer");
+  ESP_LOGI(TAG, "Time base: internal (ESP32 hardware timer)");
   return 1; // success
 
 #endif
@@ -55,18 +55,30 @@ void timepulse_start(void) {
 #elif defined RTC_INT // start external clock rtc
   attachInterrupt(digitalPinToInterrupt(RTC_INT), CLOCKIRQ, FALLING);
 #else                 // start internal clock esp32 hardware timer
+  timerAttachInterrupt(clockCycle, &CLOCKIRQ, true);
   timerAlarmEnable(clockCycle);
 #endif
 }
 
-// helper function to sync time_t of top of a second
-void sync_clock(void) {
+// helper function to sync systime on start of next second
+int sync_SysTime(time_t t) {
+  if (sync_TimePulse()) {
+    setTime(t + 1);
+    ESP_LOGD(TAG, "Systime synced on timepulse");
+    return 1; // success
+  } else
+    return 0; // failure
+}
+
+// helper function to sync moment on timepulse
+int sync_TimePulse(void) {
   // sync on top of next second by timepulse
-  if (xSemaphoreTake(TimePulse, pdMS_TO_TICKS(PPS)) == pdTRUE)
-    ESP_LOGI(TAG, "clock synced by timepulse");
+  if (xSemaphoreTake(TimePulse, pdMS_TO_TICKS(PPS)) == pdTRUE) {
+    return 1;
+  } // success
   else
-    ESP_LOGW(TAG, "Missing timepulse, clock not synced");
-  return;
+    ESP_LOGW(TAG, "Missing timepulse, time not synced");
+  return 0; // failure
 }
 
 // interrupt service routine triggered by either rtc pps or esp32 hardware
@@ -136,7 +148,6 @@ error:
 
 int set_rtctime(time_t t) { // t is seconds epoch time starting 1.1.1970
   if (I2C_MUTEX_LOCK()) {
-    sync_clock(); // wait for top of second
     Rtc.SetDateTime(RtcDateTime(t));
     I2C_MUTEX_UNLOCK(); // release i2c bus access
     ESP_LOGI(TAG, "RTC calibrated");
@@ -151,7 +162,8 @@ int set_rtctime(uint32_t t) { // t is epoch seconds starting 1.1.1970
 }
 
 time_t get_rtctime(void) {
-  // never call now() in this function, this would cause a recursion!
+  // !! never call now() or delay in this function, this would break this
+  // function to be used as SyncProvider for Time.h
   time_t t = 0;
   // block i2c bus access
   if (I2C_MUTEX_LOCK()) {