diff --git a/.mystools/cppcheck/options.sh b/.mystools/cppcheck/options.sh
index e6b4023..a907578 100755
--- a/.mystools/cppcheck/options.sh
+++ b/.mystools/cppcheck/options.sh
@@ -4,6 +4,7 @@ OPTIONS="--quiet                                      \
 	--error-exitcode=1                                  \
 	--force                                             \
 	--enable=style,information                          \
+	-DCPPCHECK                                          \
 	--library=${LIBRARY:-avr}                           \
 	--platform="${TOOLCONFIG}"/${PLATFORM:-avr.xml}     \
  	--includes-file="${TOOLCONFIG}"/includes.cfg	      \
diff --git a/hal/architecture/MyHwNRF5.cpp b/hal/architecture/MyHwNRF5.cpp
index bfad538..2543f72 100644
--- a/hal/architecture/MyHwNRF5.cpp
+++ b/hal/architecture/MyHwNRF5.cpp
@@ -196,6 +196,9 @@ void hwSleepPrepare(unsigned long ms)
 	// Enable low power sleep mode
 	NRF_POWER->TASKS_LOWPWR = 1;
 
+	// Reset RTC trigger flag
+	nrf5_rtc_event_triggered = false;
+
 	if (ms > 0) {
 		// Configure RTC
 #ifdef NRF51
@@ -204,16 +207,25 @@ void hwSleepPrepare(unsigned long ms)
 		// Reset RTC
 		MY_HW_RTC->TASKS_CLEAR = 1;
 
-		// Calculate sleep time
-		// 8 Hz -> max 582.542 hours sleep.
-		MY_HW_RTC->PRESCALER = 4095;
-		// Set compare register to 1/125ms + 2 to garantee event triggering
-		MY_HW_RTC->CC[0] = (ms / 125) + 2;
+		// Calculate sleep time and prescaler
+		if (ms<512000) {
+			// prescaler 0, 30.517 μs resolution -> max 512 s sleep
+			MY_HW_RTC->PRESCALER =  0;
+			// Set compare register to 1/30.517 µs to garantee event triggering
+			// A minimum of 2 ticks must be guaranteed
+			// (1000/32768)<<12 == 125
+			MY_HW_RTC->CC[0] = max((ms<<12 / 125), 2);
+		} else {
+			// 8 Hz -> max 582.542 hours sleep.
+			MY_HW_RTC->PRESCALER = 4095;
+			// Set compare register to 1/125ms
+			// A minimum of 2 ticks must be guaranteed
+			MY_HW_RTC->CC[0] = max((ms / 125), 2);
+		}
 
 		MY_HW_RTC->INTENSET = RTC_INTENSET_COMPARE0_Msk;
 		MY_HW_RTC->EVTENSET = RTC_EVTENSET_COMPARE0_Msk;
 		MY_HW_RTC->EVENTS_COMPARE[0] = 0;
-		nrf5_rtc_event_triggered = false;
 		MY_HW_RTC->TASKS_START = 1;
 		NVIC_SetPriority(MY_HW_RTC_IRQN, 15);
 		NVIC_ClearPendingIRQ(MY_HW_RTC_IRQN);
@@ -311,8 +323,6 @@ int8_t hwSleep(uint8_t interrupt1, uint8_t mode1, uint8_t interrupt2,
 	// and sleep might cause the MCU to not wakeup from sleep as interrupt has
 	// already be handled!
 	MY_CRITICAL_SECTION {
-		// Fix cppcheck "(style) Variable '__savePriMask' is assigned a value that is never used."
-		//(void)__savePriMask;
 		// attach interrupts
 		_wakeUp1Interrupt = interrupt1;
 		_wakeUp2Interrupt = interrupt2;
diff --git a/hal/architecture/MyHwNRF5.h b/hal/architecture/MyHwNRF5.h
index 1586d1c..07c7590 100644
--- a/hal/architecture/MyHwNRF5.h
+++ b/hal/architecture/MyHwNRF5.h
@@ -129,12 +129,14 @@ typedef struct {
 	uint8_t ciphertext[16];
 } nrf_ecb_t;
 
-#ifndef DOXYGEN
+#if !defined(DOXYGEN) && !defined(CPPCHECK)
 #define MY_CRITICAL_SECTION                                                    \
 	for (uint32_t __savePriMask                                                  \
 	        __attribute__((__cleanup__(__priMaskRestore))) = __get_PRIMASK(),       \
 	        __ToDo = __disableIntsRetVal();                                         \
 	        __ToDo; __ToDo = 0)
-#endif /* DOXYGEN */
+#else
+#define MY_CRITICAL_SECTION
+#endif /* DOXYGEN || CPPCHECK */
 
 #endif // #ifdef ARDUINO_ARCH_NRF5