Added getPrescaler( ); setPrescaler( ); for calibrating STM32F1xx during runtime.

src/STM32RTC.cpp

@@ -159,6 +159,16 @@ void STM32RTC::setPrediv(int8_t predivA, int16_t predivS)
   RTC_setPrediv(predivA, predivS);
 }
 
+
+void STM32RTC::getPrescaler(uint32_t *prescaler){
+	RTC_getPrescaler(prescaler);
+}
+
+void STM32RTC::setPrescaler(uint32_t prescaler){
+	RTC_setPrescaler(prescaler);
+}
+
+
 /**
   * @brief enable the RTC alarm.
   * @param match: Alarm_Match configuration

src/STM32RTC.h

@@ -192,6 +192,9 @@ class STM32RTC {
     void getPrediv(int8_t *predivA, int16_t *predivS);
     void setPrediv(int8_t predivA, int16_t predivS);
 
+	void getPrescaler(uint32_t *prescaler);
+	void setPrescaler(uint32_t prescaler);
+
     bool isConfigured(void)
     {
       return _configured;

src/rtc.c

@@ -248,6 +248,37 @@ void RTC_getPrediv(int8_t *asynch, int16_t *synch)
 #endif /* !STM32F1xx */
 }
 
+void RTC_setPrescaler(uint32_t prescaler)
+{
+#if defined(STM32F1xx)
+
+  /*   if(prescaler==RTC_AUTO_1_SECOND) prescaler = HAL_RCCEx_GetPeriphCLKFreq(RCC_PERIPHCLK_RTC); // Automatically calculate for 1Sec
+     SET_BIT((RtcHandle).Instance->CRL, RTC_CRL_CNF);//__HAL_RTC_WRITEPROTECTION_DISABLE(RtcHandle);
+     MODIFY_REG(RtcHandle.Instance->PRLH, RTC_PRLH_PRL, (prescaler >> 16U));
+     MODIFY_REG(RtcHandle.Instance->PRLL, RTC_PRLL_PRL, (prescaler & RTC_PRLL_PRL));
+     CLEAR_BIT((RtcHandle).Instance->CRL, RTC_CRL_CNF);//__HAL_RTC_WRITEPROTECTION_ENABLE(RtcHandle); 
+     */
+
+	RtcHandle.Init.AsynchPrediv = prescaler;
+  	HAL_RTC_Init(&RtcHandle);
+
+#else
+  UNUSED(asynch);
+  UNUSED(synch);
+#endif /* STM32F1xx */
+}
+
+void RTC_getPrescaler(uint32_t *prescaler)
+{
+#if defined(STM32F1xx)
+    // *prescaler = (((uint32_t) RtcHandle.Instance->PRLH << 16U) | READ_REG(RtcHandle.Instance->PRLL & RTC_PRLL_PRL));
+    *prescaler = RtcHandle.Init.AsynchPrediv;
+#else
+  UNUSED(asynch);
+  UNUSED(synch);
+#endif /* STM32F1xx */
+}
+
 #if !defined(STM32F1xx)
 /**
   * @brief Compute (a)synchronous prescaler
@@ -324,8 +355,8 @@ void RTC_init(hourFormat_t format, sourceClock_t source, bool reset)
 
 #if defined(STM32F1xx)
   /* Let HAL calculate the prescaler */
-  RtcHandle.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
-  RtcHandle.Init.OutPut = RTC_OUTPUTSOURCE_NONE;
+  RtcHandle.Init.AsynchPrediv = RTC_AUTO_1_SECOND;// eg: 0x8000-1 =32768-1
+  RtcHandle.Init.OutPut = RTC_OUTPUTSOURCE_NONE; /* RTC_OUTPUTSOURCE_CALIBCLOCK; RTC_OUTPUTSOURCE_NONE; RTC_OUTPUTSOURCE_ALARM; RTC_OUTPUTSOURCE_SECOND */
   UNUSED(format);
 #else
   if (format == HOUR_FORMAT_12) {

src/rtc.h

@@ -149,6 +149,9 @@ void RTC_SetClockSource(sourceClock_t source);
 void RTC_getPrediv(int8_t *asynch, int16_t *synch);
 void RTC_setPrediv(int8_t asynch, int16_t synch);
 
+void RTC_getPrescaler(uint32_t *prescaler);
+void RTC_setPrescaler(uint32_t prescaler);
+
 void RTC_init(hourFormat_t format, sourceClock_t source, bool reset);
 void RTC_DeInit(void);
 bool RTC_IsTimeSet(void);