diff --git a/platformio.ini b/platformio.ini
index 8e36506e..54912c70 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -6,7 +6,7 @@
 
 ; ---> SELECT TARGET PLATFORM HERE! <---
 [platformio]
-;env_default = generic
+env_default = generic
 ;env_default = ebox
 ;env_default = eboxtube
 ;env_default = heltec
@@ -16,7 +16,7 @@
 ;env_default = ttgov21old
 ;env_default = ttgov21new
 ;env_default = ttgobeam
-env_default = ttgofox
+;env_default = ttgofox
 ;env_default = lopy
 ;env_default = lopy4
 ;env_default = fipy
@@ -30,10 +30,10 @@ description = Paxcounter is a proof-of-concept ESP32 device for metering passeng
 
 [common]
 ; for release_version use max. 10 chars total, use any decimal format like "a.b.c"
-release_version = 1.7.323
+release_version = 1.7.324
 ; DEBUG LEVEL: For production run set to 0, otherwise device will leak RAM while running!
 ; 0=None, 1=Error, 2=Warn, 3=Info, 4=Debug, 5=Verbose
-debug_level = 4
+debug_level = 0
 ; UPLOAD MODE: select esptool to flash via USB/UART, select custom to upload to cloud for OTA
 upload_protocol = esptool
 ;upload_protocol = custom
diff --git a/src/main.cpp b/src/main.cpp
index bf32e01d..547b2d25 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -358,13 +358,18 @@ void setup() {
 #endif
 #endif
 
+#if defined HAS_IF482 || defined HAS_DCF77
   // start pps timepulse
   ESP_LOGI(TAG, "Starting Timekeeper...");
   assert(timepulse_init()); // setup timepulse
   timepulse_start();
+#endif
+
+#ifdef TIME_SYNC_INTERVAL
   // set time source and sync time
   setSyncInterval(TIME_SYNC_INTERVAL * 60);
   setSyncProvider(&timeProvider);
+#endif
 
   // start wifi in monitor mode and start channel rotation timer
   ESP_LOGI(TAG, "Starting Wifi...");
diff --git a/src/paxcounter.conf b/src/paxcounter.conf
index 98087310..f5251bdd 100644
--- a/src/paxcounter.conf
+++ b/src/paxcounter.conf
@@ -66,7 +66,7 @@
 #define RESPONSE_TIMEOUT_MS             60000   // firmware binary server connection timeout [milliseconds]
 
 // settings for syncing time of node with external time source
-#define TIME_SYNC_INTERVAL              2      // sync time attempt each .. minutes from time source (GPS/LORA/RTC) [default = 60], comment out means off
+//#define TIME_SYNC_INTERVAL              2      // sync time attempt each .. minutes from time source (GPS/LORA/RTC) [default = 60], comment out means off
 //#define TIME_SYNC_LORA                  1       // use LORA network as time source, comment out means off [default = off]
 
 // time zone, see https://github.com/JChristensen/Timezone/blob/master/examples/WorldClock/WorldClock.ino
diff --git a/src/timekeeper.cpp b/src/timekeeper.cpp
index 9fd671c6..8a40f56e 100644
--- a/src/timekeeper.cpp
+++ b/src/timekeeper.cpp
@@ -100,17 +100,23 @@ void timepulse_start(void) {
 // interrupt service routine triggered by either pps or esp32 hardware timer
 void IRAM_ATTR CLOCKIRQ(void) {
 
+  BaseType_t xHigherPriorityTaskWoken;
+
   time_t t = SyncToPPS(); // calibrates UTC systime, see Time.h
+  xHigherPriorityTaskWoken = pdFALSE;
 
   if (ClockTask != NULL)
-    xTaskNotifyFromISR(ClockTask, uint32_t(t), eSetBits, NULL);
+    xTaskNotifyFromISR(ClockTask, uint32_t(t), eSetBits,
+                       &xHigherPriorityTaskWoken);
 
 #if defined GPS_INT || defined RTC_INT
-  xSemaphoreGiveFromISR(TimePulse, NULL);
+  xSemaphoreGiveFromISR(TimePulse, &xHigherPriorityTaskWoken);
   TimePulseTick = !TimePulseTick; // flip ticker
 #endif
 
-  portYIELD_FROM_ISR();
+  // yield only if we should
+  if (xHigherPriorityTaskWoken)
+    portYIELD_FROM_ISR();
 }
 
 // helper function to check plausibility of a time
@@ -215,9 +221,9 @@ void clock_loop(void *taskparameter) { // ClockTask
     if (second(t) == DCF77_FRAME_SIZE - 1) // is it time to load new frame?
       DCFpulse = DCF77_Frame(nextmin(t));  // generate frame for next minute
 
-    if (minute(nextmin(t)) ==            // do we still have a recent frame?
-        DCFpulse[DCF77_FRAME_SIZE])      // (timepulses could be missed!)
-      DCF77_Pulse(t, DCFpulse); // then output current second's pulse
+    if (minute(nextmin(t)) ==       // do we still have a recent frame?
+        DCFpulse[DCF77_FRAME_SIZE]) // (timepulses could be missed!)
+      DCF77_Pulse(t, DCFpulse);     // then output current second's pulse
     else
       continue; // no recent frame -> we suppress clock output