diff --git a/src/CatenaSamd21.h b/src/CatenaSamd21.h
index 60b3154..d434741 100644
--- a/src/CatenaSamd21.h
+++ b/src/CatenaSamd21.h
@@ -83,6 +83,11 @@ class CatenaSamd21 : public CatenaBase
 
 	virtual void Sleep(uint32_t howLongInSeconds) override;
 
+	CatenaRTC::CalendarTime GetCalendarTime(void)
+		{
+		return this->m_Rtc.GetTime();
+		}
+
 protected:
 	virtual void registerCommands(void);
 
diff --git a/src/CatenaStm32L0.h b/src/CatenaStm32L0.h
index f917d1d..0f47c18 100644
--- a/src/CatenaStm32L0.h
+++ b/src/CatenaStm32L0.h
@@ -102,6 +102,11 @@ class CatenaStm32L0 : public CatenaStm32
 
 	virtual void Sleep(uint32_t howLongInSeconds) override;
 
+	CatenaStm32L0Rtc::CalendarTime GetCalendarTime(void)
+		{
+		return this->m_Rtc.GetTime();
+		}
+
 protected:
 	// methods
 	virtual void registerCommands(void);
diff --git a/src/lib/stm32/stm32l0/CatenaStm32L0Rtc.cpp b/src/lib/stm32/stm32l0/CatenaStm32L0Rtc.cpp
index 9f1b035..82fbf17 100644
--- a/src/lib/stm32/stm32l0/CatenaStm32L0Rtc.cpp
+++ b/src/lib/stm32/stm32l0/CatenaStm32L0Rtc.cpp
@@ -16,6 +16,8 @@ Copyright notice:
 #ifdef ARDUINO_ARCH_STM32
 
 #include "CatenaStm32L0Rtc.h"
+#include "Catena_Log.h"
+
 using namespace McciCatena;
 
 /****************************************************************************\
@@ -128,20 +130,38 @@ bool CatenaStm32L0Rtc::begin(bool fResetTime)
 	{
 	RTC_TimeTypeDef	Time;
 	RTC_DateTypeDef	Date;
+	uint32_t RtcClock;
 
 //	memset(&this->m_hRtc, 0, sizeof(this->m_hRtc));
 
 	this->m_hRtc.Instance = RTC;
 	this->m_hRtc.Init.HourFormat = RTC_HOURFORMAT_24;
-//	this->m_hRtc.Init.AsynchPrediv = 37 - 1; /* 37kHz / 37 = 1000Hz */
-//	this->m_hRtc.Init.SynchPrediv = 1000 - 1; /* 1000Hz / 1000 = 1Hz */
-
-//	this->m_hRtc.Init.AsynchPrediv = 64 - 1; /* 40kHz / 64 = 625Hz */
-//	this->m_hRtc.Init.SynchPrediv = 625 - 1; /* 625Hz / 625 = 1Hz */
+	RtcClock = __HAL_RCC_GET_RTC_SOURCE();
+	if (RtcClock == RCC_RTCCLKSOURCE_LSI)
+		{
+		this->m_hRtc.Init.AsynchPrediv = 37 - 1; /* 37kHz / 37 = 1000Hz */
+		this->m_hRtc.Init.SynchPrediv = 1000 - 1; /* 1000Hz / 1000 = 1Hz */
+		}
+	else if (RtcClock == RCC_RTCCLKSOURCE_LSE)
+		{
+		this->m_hRtc.Init.AsynchPrediv = 128 - 1; /* 32768Hz / 128 = 256Hz */
+		this->m_hRtc.Init.SynchPrediv = 256 - 1; /* 256Hz / 256 = 1Hz */
+		}
+	else
+		{
+		/*
+		|| use HSE clock --
+		|| we don't support use of HSE as RTC because it's connected to
+		|| TCXO_OUT, and that's controlled by the LoRaWAN software.
+		*/
+		gLog.printf(
+			gLog.kError,
+			"?CatenaStm32L0Rtc::begin:"
+			" HSE can not be used for RTC clock!\n"
+			);
+		return false;
+		}
 
-	this->m_hRtc.Init.AsynchPrediv = 128 - 1; /* 32768Hz / 128 = 256Hz */
-//	this->m_hRtc.Init.SynchPrediv = 256 - 1; /* 256Hz / 256 = 1Hz */
-	this->m_hRtc.Init.SynchPrediv = 256; /* 256Hz / 256 = 1Hz */
 
 	this->m_hRtc.Init.OutPut = RTC_OUTPUT_DISABLE;
 	this->m_hRtc.Init.OutPutRemap = RTC_OUTPUT_REMAP_NONE;
@@ -152,7 +172,11 @@ bool CatenaStm32L0Rtc::begin(bool fResetTime)
 
 	if (HAL_RTC_Init(&this->m_hRtc) != HAL_OK)
 		{
-		Serial.println("HAL_RTC_Init() failed");
+		gLog.printf(
+			gLog.kError,
+			"?CatenaStm32L0Rtc::begin:"
+			" HAL_RTC_Init() failed\n"
+			);
 		return false;
 		}
 
@@ -174,7 +198,11 @@ bool CatenaStm32L0Rtc::begin(bool fResetTime)
 			RTC_FORMAT_BIN
 			) != HAL_OK)
 			{
-			Serial.println("HAL_RTC_SetTime() failed");
+			gLog.printf(
+				gLog.kError,
+				"?CatenaStm32L0Rtc::begin:"
+				" HAL_RTC_SetTime() failed\n"
+				);
 			return false;
 			}
 
@@ -190,7 +218,11 @@ bool CatenaStm32L0Rtc::begin(bool fResetTime)
 			RTC_FORMAT_BIN
 			) != HAL_OK)
 			{
-			Serial.println("HAL_RTC_SetDate() failed");
+			gLog.printf(
+			gLog.kError,
+				"?CatenaStm32L0Rtc::begin:"
+				" HAL_RTC_SetDate() failed\n"
+				);
 			return false;
 			}
 
@@ -249,7 +281,11 @@ bool CatenaStm32L0Rtc::SetTime(const CalendarTime *pNow)
 
 	if (HAL_RTC_SetTime(&this->m_hRtc, &Time, RTC_FORMAT_BIN) != HAL_OK)
 		{
-		Serial.println("HAL_RTC_SetTime() failed");
+		gLog.printf(
+			gLog.kError,
+			"?CatenaStm32L0Rtc::begin:"
+			" HAL_RTC_SetTime() failed\n"
+			);
 		return false;
 		}
 
@@ -260,7 +296,11 @@ bool CatenaStm32L0Rtc::SetTime(const CalendarTime *pNow)
 
 	if (HAL_RTC_SetDate(&this->m_hRtc, &Date, RTC_FORMAT_BIN) != HAL_OK)
 		{
-		Serial.println("HAL_RTC_SetDate() failed");
+		gLog.printf(
+			gLog.kError,
+			"?CatenaStm32L0Rtc::begin:"
+			" HAL_RTC_SetDate() failed\n"
+			);
 		return false;
 		}