diff --git a/cores/arduino/board.h b/cores/arduino/board.h
index 194f4ebd7a..3ca81179e2 100644
--- a/cores/arduino/board.h
+++ b/cores/arduino/board.h
@@ -14,6 +14,7 @@ extern "C"{
 #include "digital_io.h"
 #include "hal_uart_emul.h"
 #include "hw_config.h"
+#include "rtc.h"
 #include "spi_com.h"
 #include "stm32_eeprom.h"
 #include "timer.h"
diff --git a/cores/arduino/stm32/rtc.c b/cores/arduino/stm32/rtc.c
new file mode 100644
index 0000000000..68076c8f0f
--- /dev/null
+++ b/cores/arduino/stm32/rtc.c
@@ -0,0 +1,677 @@
+/**
+  ******************************************************************************
+  * @file    rtc.c
+  * @author  WI6LABS
+  * @version V1.0.0
+  * @date    12-December-2017
+  * @brief   Provides a RTC driver
+  *
+  ******************************************************************************
+  * @attention
+  *
+  * <h2><center>&copy; COPYRIGHT(c) 2017 STMicroelectronics</center></h2>
+  *
+  * Redistribution and use in source and binary forms, with or without modification,
+  * are permitted provided that the following conditions are met:
+  *   1. Redistributions of source code must retain the above copyright notice,
+  *      this list of conditions and the following disclaimer.
+  *   2. Redistributions in binary form must reproduce the above copyright notice,
+  *      this list of conditions and the following disclaimer in the documentation
+  *      and/or other materials provided with the distribution.
+  *   3. Neither the name of STMicroelectronics nor the names of its contributors
+  *      may be used to endorse or promote products derived from this software
+  *      without specific prior written permission.
+  *
+  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+  *
+  ******************************************************************************
+  */
+
+#include "rtc.h"
+
+#ifdef HAL_RTC_MODULE_ENABLED
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+/* Private define ------------------------------------------------------------*/
+/* Private macro -------------------------------------------------------------*/
+/* Private variables ---------------------------------------------------------*/
+static RTC_HandleTypeDef RtcHandle = {0};
+static voidCallbackPtr RTCUserCallback = NULL;
+static void *callbackUserData = NULL;
+
+static sourceClock_t clkSrc = LSI_CLOCK;
+static uint8_t HSEDiv = 0;
+#if !defined(STM32F1xx)
+/* Custom user values */
+static int8_t userPredivAsync = -1;
+static int16_t userPredivSync = -1;
+#endif /* !STM32F1xx */
+
+static hourFormat_t initFormat = HOUR_FORMAT_12;
+
+/* Private function prototypes -----------------------------------------------*/
+static void RTC_initClock(sourceClock_t source);
+#if !defined(STM32F1xx)
+static void RTC_computePrediv(int8_t *asynch, int16_t *synch);
+#endif /* !STM32F1xx */
+
+/* Exported functions --------------------------------------------------------*/
+
+/**
+  * @brief Set RTC clock source
+  * @param source: RTC clock source: LSE, LSI or HSE
+  * @retval None
+  */
+void RTC_SetClockSource(sourceClock_t source)
+{
+  switch(source) {
+    case LSI_CLOCK:
+    case LSE_CLOCK:
+    case HSE_CLOCK:
+      clkSrc = source;
+      break;
+    default:
+      clkSrc = LSI_CLOCK;
+      break;
+  }
+}
+
+/**
+  * @brief RTC clock initialization
+  *        This function configures the hardware resources used.
+  * @param source: RTC clock source: LSE, LSI or HSE
+  * @note  Care must be taken when HAL_RCCEx_PeriphCLKConfig() is used to select
+  *        the RTC clock source; in this case the Backup domain will be reset in
+  *        order to modify the RTC Clock source, as consequence RTC registers (including
+  *        the backup registers) and RCC_CSR register are set to their reset values.
+  * @retval None
+  */
+static void RTC_initClock(sourceClock_t source)
+{
+  RCC_OscInitTypeDef RCC_OscInitStruct;
+  RCC_PeriphCLKInitTypeDef PeriphClkInit;
+
+  if(source == LSE_CLOCK) {
+    /* Enable the clock if not already set by user */
+    if(__HAL_RCC_GET_FLAG(RCC_FLAG_LSERDY) == RESET) {
+#ifdef __HAL_RCC_LSEDRIVE_CONFIG
+      __HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
+#endif
+      RCC_OscInitStruct.OscillatorType =  RCC_OSCILLATORTYPE_LSE;
+      RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
+      RCC_OscInitStruct.LSEState = RCC_LSE_ON;
+      if(HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
+        Error_Handler();
+      }
+    }
+
+    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC;
+    PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
+    if(HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) {
+      Error_Handler();
+    }
+    clkSrc = LSE_CLOCK;
+  } else if(source == HSE_CLOCK) {
+    /* Enable the clock if not already set by user */
+    if(__HAL_RCC_GET_FLAG(RCC_FLAG_HSERDY) == RESET) {
+      RCC_OscInitStruct.OscillatorType =  RCC_OSCILLATORTYPE_HSE;
+      RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
+      RCC_OscInitStruct.HSEState = RCC_HSE_ON;
+      if(HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
+        Error_Handler();
+      }
+    }
+    /* HSE division factor for RTC clock must be set to ensure that
+     * the clock supplied to the RTC is less than or equal to 1 MHz
+     */
+    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC;
+#if defined(STM32F1xx)
+    /* HSE max is 16 MHZ divided by 128 --> 125 KHz */
+    PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV128;
+    HSEDiv = 128;
+#elif defined(STM32F0xx) || defined(STM32F3xx) || defined(STM32L4xx)
+    PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV32;
+    HSEDiv = 32;
+#elif defined(STM32L0xx) || defined(STM32L1xx)
+    if((HSE_VALUE/2) <= HSE_RTC_MAX) {
+      PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV2;
+      HSEDiv = 2;
+    } else if((HSE_VALUE/4) <= HSE_RTC_MAX) {
+      PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV4;
+      HSEDiv = 4;
+    } else if((HSE_VALUE/8) <= HSE_RTC_MAX) {
+      PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV8;
+      HSEDiv = 8;
+    } else if((HSE_VALUE/16) <= HSE_RTC_MAX) {
+      PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV16;
+      HSEDiv = 16;
+    }
+#elif defined(STM32F2xx) || defined(STM32F4xx) || defined(STM32F7xx)
+/* Not defined for STM32F2xx */
+#ifndef RCC_RTCCLKSOURCE_HSE_DIVX
+#define RCC_RTCCLKSOURCE_HSE_DIVX 0x00000300U
+#endif /* RCC_RTCCLKSOURCE_HSE_DIVX */
+    for(HSEDiv = 2; HSEDiv<32; HSEDiv++) {
+      if((HSE_VALUE/HSEDiv) <= HSE_RTC_MAX) {
+        PeriphClkInit.RTCClockSelection = (HSEDiv<<16) | RCC_RTCCLKSOURCE_HSE_DIVX;
+        break;
+      }
+    }
+#else
+#error "Unknown Family - could not define RTCClockSelection"
+#endif /* STM32F1xx */
+    if((HSE_VALUE/HSEDiv) > HSE_RTC_MAX) {
+      Error_Handler();
+    }
+
+    if(HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) {
+      Error_Handler();
+    }
+    clkSrc = HSE_CLOCK;
+  } else if(source == LSI_CLOCK) {
+    /* Enable the clock if not already set by user */
+    if(__HAL_RCC_GET_FLAG(RCC_FLAG_LSIRDY) == RESET) {
+      RCC_OscInitStruct.OscillatorType =  RCC_OSCILLATORTYPE_LSI;
+      RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
+      RCC_OscInitStruct.LSIState = RCC_LSI_ON;
+      if(HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
+        Error_Handler();
+      }
+    }
+
+    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC;
+    PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSI;
+    if(HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) {
+      Error_Handler();
+    }
+    clkSrc = LSI_CLOCK;
+  } else {
+    Error_Handler();
+  }
+
+  __HAL_RCC_RTC_ENABLE();
+}
+
+/**
+  * @brief set user (a)synchronous prescaler values.
+  * @note  use -1 to reset value and use computed ones
+  * @param asynch: asynchronous prescaler value in range 0 - PREDIVA_MAX
+  * @param synch: synchronous prescaler value in range 0 - PREDIVS_MAX
+  * @retval None
+  */
+void RTC_setPrediv(int8_t asynch, int16_t synch)
+{
+#if !defined(STM32F1xx)
+  if((asynch >= -1) && (synch >= -1)) {
+    userPredivAsync = asynch;
+    userPredivSync = synch;
+  }
+#else
+  UNUSED(asynch);
+  UNUSED(synch);
+#endif /* !STM32F1xx */
+}
+
+/**
+  * @brief get user (a)synchronous prescaler values if set else computed ones
+  *        for the current clock source.
+  * @param asynch: pointer where return asynchronous prescaler value.
+  * @param synch: pointer where return synchronous prescaler value.
+  * @retval None
+  */
+void RTC_getPrediv(int8_t *asynch, int16_t *synch)
+{
+#if !defined(STM32F1xx)
+  if((userPredivAsync == -1) || (userPredivSync == -1)) {
+    RTC_computePrediv(asynch, synch);
+  } else {
+    if((asynch != NULL) && (synch != NULL)) {
+      *asynch = userPredivAsync;
+      *synch = userPredivSync;
+    }
+  }
+#else
+  UNUSED(asynch);
+  UNUSED(synch);
+#endif /* !STM32F1xx */
+}
+
+#if !defined(STM32F1xx)
+/**
+  * @brief Compute (a)synchronous prescaler
+  *        RTC prescalers are compute to obtain the RTC clock to 1Hz. See AN4759.
+  * @param asynch: pointer where return asynchronous prescaler value.
+  * @param synch: pointer where return synchronous prescaler value.
+  * @retval None
+  */
+static void RTC_computePrediv(int8_t *asynch, int16_t *synch)
+{
+  uint32_t predivS = PREDIVS_MAX + 1;
+  uint32_t clk = 0;
+
+  /* Get user predividers if manually configured */
+  if((asynch == NULL) || (synch == NULL)) {
+    return;
+  }
+
+  /* Get clock frequency */
+  if(clkSrc == LSE_CLOCK) {
+    clk = LSE_VALUE;
+  }
+  else if(clkSrc == LSI_CLOCK) {
+    clk = LSI_VALUE;
+  }
+  else if(clkSrc == HSE_CLOCK) {
+    clk = HSE_VALUE/HSEDiv;
+  } else {
+    Error_Handler();
+  }
+
+  /* Find (a)synchronous prescalers to obtain the 1Hz calendar clock */
+  for(*asynch = PREDIVA_MAX; *asynch >= 0; (*asynch)--) {
+    predivS = (clk / (*asynch + 1)) - 1;
+
+    if(((predivS + 1) * (*asynch + 1)) == clk)
+      break;
+  }
+
+  /*
+   * Can't find a 1Hz, so give priority to RTC power consumption
+   * by choosing the higher possible value for predivA
+   */
+  if((predivS > PREDIVS_MAX) || (*asynch < 0 )) {
+    *asynch = PREDIVA_MAX;
+    predivS = (clk / (*asynch + 1)) - 1;
+  }
+
+  if(predivS > PREDIVS_MAX) {
+    Error_Handler();
+  }
+  *synch = (int16_t)predivS;
+}
+#endif /* !STM32F1xx */
+
+/**
+  * @brief RTC Initialization
+  *        This function configures the RTC time and calendar. By default, the
+  *        RTC is set to the 1st January 2017 0:0:0:00
+  * @param format: enable the RTC in 12 or 24 hours mode
+  * @retval None
+  */
+void RTC_init(hourFormat_t format, sourceClock_t source)
+{
+  initFormat = format;
+
+  /* Init RTC clock */
+  RTC_initClock(source);
+
+  RtcHandle.Instance = RTC;
+
+#if defined(STM32F1xx)
+  /* Let HAL calculate the prescaler */
+  RtcHandle.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
+  RtcHandle.Init.OutPut = RTC_OUTPUTSOURCE_NONE;
+  UNUSED(format);
+#else
+  if(format == HOUR_FORMAT_12) {
+    RtcHandle.Init.HourFormat = RTC_HOURFORMAT_12;
+  } else {
+    RtcHandle.Init.HourFormat = RTC_HOURFORMAT_24;
+  }
+  RtcHandle.Init.OutPut = RTC_OUTPUT_DISABLE;
+  RTC_getPrediv((int8_t*)&(RtcHandle.Init.AsynchPrediv), (int16_t*)&(RtcHandle.Init.SynchPrediv));
+#if defined(STM32L0xx) || defined(STM32L4xx)
+  RtcHandle.Init.OutPutRemap = RTC_OUTPUT_REMAP_NONE;
+#endif /* STM32L0xx || STM32L4xx */
+  RtcHandle.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
+  RtcHandle.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
+#endif /* STM32F1xx */
+
+  HAL_RTC_Init( &RtcHandle );
+
+  /*Sunday 1st January 2017*/
+  RTC_SetDate(17, 1, 1, 7);
+
+  /*at 0:0:0*/
+  RTC_SetTime(0,0,0,0,AM);
+
+#if !defined(STM32F1xx) && !defined(STM32F2xx)
+  /* Enable Direct Read of the calendar registers (not through Shadow) */
+  HAL_RTCEx_EnableBypassShadow(&RtcHandle);
+#endif /* !STM32F1xx && !STM32F2xx */
+
+  HAL_NVIC_SetPriority(RTC_Alarm_IRQn, 2, 0);
+  HAL_NVIC_EnableIRQ(RTC_Alarm_IRQn);
+}
+
+/**
+  * @brief RTC deinitialization. Stop the RTC.
+  * @retval None
+  */
+void RTC_DeInit(void)
+{
+  HAL_RTC_DeInit(&RtcHandle);
+  RTCUserCallback = NULL;
+  callbackUserData = NULL;
+}
+
+/**
+  * @brief Set RTC time
+  * @param hours: 0-12 or 0-23. Depends on the format used.
+  * @param minutes: 0-59
+  * @param seconds: 0-59
+  * @param subSeconds: 0-999
+  * @param period: select AM or PM period in case RTC is set in 12 hours mode. Else ingored.
+  * @retval None
+  */
+void RTC_SetTime(uint8_t hours, uint8_t minutes, uint8_t seconds, uint32_t subSeconds, hourAM_PM_t period)
+{
+  RTC_TimeTypeDef RTC_TimeStruct;
+
+  /* Ignore time AM PM configuration if in 24 hours format */
+  if(initFormat == HOUR_FORMAT_24) {
+    period = AM;
+  }
+
+  if((((initFormat == HOUR_FORMAT_24) && IS_RTC_HOUR24(hours)) || IS_RTC_HOUR12(hours))
+      && IS_RTC_MINUTES(minutes) && IS_RTC_SECONDS(seconds)) {
+    RTC_TimeStruct.Hours = hours;
+    RTC_TimeStruct.Minutes = minutes;
+    RTC_TimeStruct.Seconds = seconds;
+#if !defined(STM32F1xx)
+    if(period == PM) {
+      RTC_TimeStruct.TimeFormat = RTC_HOURFORMAT12_PM;
+    } else {
+      RTC_TimeStruct.TimeFormat = RTC_HOURFORMAT12_AM;
+    }
+#if !defined(STM32F2xx) && !defined(STM32L1xx) || defined(STM32L1_ULPH)
+    RTC_TimeStruct.SubSeconds = subSeconds;
+    RTC_TimeStruct.SecondFraction = 0;
+#else
+    UNUSED(subSeconds);
+#endif /* !STM32F2xx && !STM32L1xx || STM32L1_ULPH */
+    RTC_TimeStruct.DayLightSaving = RTC_STOREOPERATION_RESET;
+    RTC_TimeStruct.StoreOperation = RTC_DAYLIGHTSAVING_NONE;
+#else
+    UNUSED(subSeconds);
+    UNUSED(period);
+#endif /* !STM32F1xx */
+
+    HAL_RTC_SetTime(&RtcHandle , &RTC_TimeStruct, RTC_FORMAT_BIN);
+  }
+}
+
+/**
+  * @brief Get RTC time
+  * @param hours: 0-12 or 0-23. Depends on the format used.
+  * @param minutes: 0-59
+  * @param seconds: 0-59
+  * @param subSeconds: 0-999
+  * @param period: returns AM or PM period in case RTC is set in 12 hours mode.
+  * @retval None
+  */
+void RTC_GetTime(uint8_t *hours, uint8_t *minutes, uint8_t *seconds, uint32_t *subSeconds, hourAM_PM_t *period)
+{
+  RTC_TimeTypeDef RTC_TimeStruct;
+
+  if((hours != NULL) && (minutes != NULL) && (seconds != NULL) && (subSeconds != NULL) && (period != NULL)) {
+    HAL_RTC_GetTime(&RtcHandle , &RTC_TimeStruct, RTC_FORMAT_BIN);
+    *hours = RTC_TimeStruct.Hours;
+    *minutes = RTC_TimeStruct.Minutes;
+    *seconds = RTC_TimeStruct.Seconds;
+#if !defined(STM32F1xx)
+    if(RTC_TimeStruct.TimeFormat == RTC_HOURFORMAT12_PM) {
+      *period = PM;
+    } else {
+      *period = AM;
+    }
+#if (!defined(STM32F2xx) && !defined(STM32L1xx)) || defined(STM32L1_ULPH)
+    *subSeconds = RTC_TimeStruct.SubSeconds;
+#endif
+#endif /* !STM32F1xx */
+  }
+}
+
+/**
+  * @brief Set RTC calendar
+  * @param year: 0-99
+  * @param month: 1-12
+  * @param day: 1-31
+  * @param wday: 1-7
+  * @retval None
+  */
+void RTC_SetDate(uint8_t year, uint8_t month, uint8_t day, uint8_t wday)
+{
+  RTC_DateTypeDef RTC_DateStruct;
+
+  if(IS_RTC_YEAR(year) && IS_RTC_MONTH(month) && IS_RTC_DATE(day) && IS_RTC_WEEKDAY(wday)) {
+    RTC_DateStruct.Year = year;
+    RTC_DateStruct.Month = month;
+    RTC_DateStruct.Date = day;
+    RTC_DateStruct.WeekDay = wday;
+    HAL_RTC_SetDate(&RtcHandle , &RTC_DateStruct, RTC_FORMAT_BIN);
+  }
+}
+
+/**
+  * @brief Get RTC calendar
+  * @param year: 0-99
+  * @param month: 1-12
+  * @param day: 1-31
+  * @param wday: 1-7
+  * @retval None
+  */
+void RTC_GetDate(uint8_t *year, uint8_t *month, uint8_t *day, uint8_t *wday)
+{
+  RTC_DateTypeDef RTC_DateStruct;
+
+  if((year != NULL) && (month != NULL) && (day != NULL) && (wday != NULL)) {
+    HAL_RTC_GetDate(&RtcHandle, &RTC_DateStruct, RTC_FORMAT_BIN);
+    *year = RTC_DateStruct.Year;
+    *month = RTC_DateStruct.Month;
+    *day = RTC_DateStruct.Date;
+    *wday = RTC_DateStruct.WeekDay;
+  }
+}
+
+/**
+  * @brief Set RTC alarm and activate it with IT mode
+  * @param day: 1-31 (day of the month)
+  * @param hours: 0-12 or 0-23 depends on the hours mode.
+  * @param minutes: 0-59
+  * @param seconds: 0-59
+  * @param subSeconds: 0-999
+  * @param period: AM or PM if in 12 hours mode else ignored.
+  * @param mask: configure alarm behavior using alarmMask_t combination.
+  *              See AN4579 Table 5 for possible values.
+  * @retval None
+  */
+void RTC_StartAlarm(uint8_t day, uint8_t hours, uint8_t minutes, uint8_t seconds, uint32_t subSeconds, hourAM_PM_t period, uint8_t mask)
+{
+  RTC_AlarmTypeDef RTC_AlarmStructure;
+
+  /* Ignore time AM PM configuration if in 24 hours format */
+  if(initFormat == HOUR_FORMAT_24) {
+    period = AM;
+  }
+
+  if((((initFormat == HOUR_FORMAT_24) && IS_RTC_HOUR24(hours)) || IS_RTC_HOUR12(hours))
+    && IS_RTC_DATE(day) && IS_RTC_MINUTES(minutes) && IS_RTC_SECONDS(seconds)) {
+    /* Set RTC_AlarmStructure with calculated values*/
+    /* Use alarm A by default because it is common to all STM32 HAL */
+    RTC_AlarmStructure.Alarm = RTC_ALARM_A;
+    RTC_AlarmStructure.AlarmTime.Seconds = seconds;
+    RTC_AlarmStructure.AlarmTime.Minutes = minutes;
+    RTC_AlarmStructure.AlarmTime.Hours = hours;
+#if !defined(STM32F1xx)
+#if !defined(STM32F2xx) && !defined(STM32L1xx) || defined(STM32L1_ULPH)
+    RTC_AlarmStructure.AlarmSubSecondMask = RTC_ALARMSUBSECONDMASK_SS14_10;
+    RTC_AlarmStructure.AlarmTime.SubSeconds = subSeconds;
+#else
+    UNUSED(subSeconds);
+#endif /* !STM32F2xx && !STM32L1xx || STM32L1_ULPH */
+    if(period == PM) {
+      RTC_AlarmStructure.AlarmTime.TimeFormat = RTC_HOURFORMAT12_PM;
+    } else {
+      RTC_AlarmStructure.AlarmTime.TimeFormat = RTC_HOURFORMAT12_AM;
+    }
+    RTC_AlarmStructure.AlarmTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
+    RTC_AlarmStructure.AlarmTime.StoreOperation = RTC_STOREOPERATION_RESET;
+    RTC_AlarmStructure.AlarmDateWeekDay = day;
+    RTC_AlarmStructure.AlarmDateWeekDaySel = RTC_ALARMDATEWEEKDAYSEL_DATE;
+    /* configure AlarmMask (M_MSK and Y_MSK ignored) */
+	if(mask == OFF_MSK) {
+      RTC_AlarmStructure.AlarmMask = RTC_ALARMMASK_ALL;
+	} else {
+      RTC_AlarmStructure.AlarmMask = RTC_ALARMMASK_NONE;
+      if( !(mask & SS_MSK)) {
+        RTC_AlarmStructure.AlarmMask |= RTC_ALARMMASK_SECONDS;
+      }
+      if( !(mask & MM_MSK)) {
+        RTC_AlarmStructure.AlarmMask |= RTC_ALARMMASK_MINUTES;
+      }
+      if( !(mask & HH_MSK)) {
+        RTC_AlarmStructure.AlarmMask |= RTC_ALARMMASK_HOURS;
+      }
+      if( !(mask & D_MSK)) {
+        RTC_AlarmStructure.AlarmMask |= RTC_ALARMMASK_DATEWEEKDAY;
+      }
+    }
+#else
+    UNUSED(subSeconds);
+    UNUSED(period);
+    UNUSED(day);
+    UNUSED(mask);
+#endif /* !STM32F1xx */
+
+    /* Set RTC_Alarm */
+    HAL_RTC_SetAlarm_IT(&RtcHandle, &RTC_AlarmStructure, RTC_FORMAT_BIN);
+  }
+}
+
+/**
+  * @brief Disable RTC alarm
+  * @param None
+  * @retval None
+  */
+void RTC_StopAlarm(void)
+{
+  /* Clear RTC Alarm Flag */
+  __HAL_RTC_ALARM_CLEAR_FLAG(&RtcHandle, RTC_FLAG_ALRAF);
+
+  /* Disable the Alarm A interrupt */
+  HAL_RTC_DeactivateAlarm(&RtcHandle, RTC_ALARM_A);
+}
+
+/**
+  * @brief Get RTC alarm
+  * @param day: 1-31 (day of the month)
+  * @param hours: 0-12 or 0-23 depends on the hours mode.
+  * @param minutes: 0-59
+  * @param seconds: 0-59
+  * @param subSeconds: 0-999
+  * @param period: AM or PM
+  * @retval None
+  */
+void RTC_GetAlarm(uint8_t *day, uint8_t *hours, uint8_t *minutes, uint8_t *seconds, uint32_t *subSeconds, hourAM_PM_t *period, uint8_t *mask)
+{
+  RTC_AlarmTypeDef RTC_AlarmStructure;
+
+  if((day != NULL) && (hours != NULL) && (minutes != NULL) && (seconds != NULL) && (subSeconds != NULL) && (period != NULL) && (mask != NULL)) {
+    HAL_RTC_GetAlarm(&RtcHandle, &RTC_AlarmStructure, RTC_ALARM_A, RTC_FORMAT_BIN);
+
+    *seconds = RTC_AlarmStructure.AlarmTime.Seconds;
+    *minutes = RTC_AlarmStructure.AlarmTime.Minutes;
+    *hours = RTC_AlarmStructure.AlarmTime.Hours;
+
+#if !defined(STM32F1xx)
+    *day = RTC_AlarmStructure.AlarmDateWeekDay;
+    if(RTC_AlarmStructure.AlarmTime.TimeFormat == RTC_HOURFORMAT12_PM) {
+      *period = PM;
+    } else {
+      *period = AM;
+    }
+#if !defined(STM32F2xx) && !defined(STM32L1xx) || defined(STM32L1_ULPH)
+    *subSeconds = RTC_AlarmStructure.AlarmTime.SubSeconds;
+#endif /* !STM32F2xx && !STM32L1xx || STM32L1_ULPH */
+    *mask = OFF_MSK;
+    if(!(RTC_AlarmStructure.AlarmMask & RTC_ALARMMASK_SECONDS)) {
+      *mask |= SS_MSK;
+    }
+    if(!(RTC_AlarmStructure.AlarmMask & RTC_ALARMMASK_MINUTES)) {
+      *mask |= MM_MSK;
+    }
+    if(!(RTC_AlarmStructure.AlarmMask & RTC_ALARMMASK_HOURS)) {
+      *mask |= HH_MSK;
+    }
+    if(!(RTC_AlarmStructure.AlarmMask & RTC_ALARMMASK_DATEWEEKDAY)) {
+      *mask |= D_MSK;
+    }
+#endif /* !STM32F1xx */
+  }
+}
+
+/**
+  * @brief Attach alarm callback.
+  * @param func: pointer to the callback
+  * @retval None
+  */
+void attachAlarmCallback(voidCallbackPtr func, void *data)
+{
+  RTCUserCallback = func;
+  callbackUserData = data;
+}
+
+/**
+  * @brief Detach alarm callback.
+  * @param None
+  * @retval None
+  */
+void detachAlarmCallback(void)
+{
+  RTCUserCallback = NULL;
+  callbackUserData = NULL;
+}
+
+/**
+  * @brief  Alarm A callback.
+  * @param  hrtc RTC handle
+  * @retval None
+  */
+void HAL_RTC_AlarmAEventCallback(RTC_HandleTypeDef *hrtc)
+{
+  UNUSED(hrtc);
+
+  if(RTCUserCallback != NULL)
+    RTCUserCallback(callbackUserData);
+}
+
+/**
+  * @brief  RTC Alarm IRQHandler
+  * @param  None
+  * @retval None
+  */
+void RTC_Alarm_IRQHandler(void)
+{
+  HAL_RTC_AlarmIRQHandler(&RtcHandle);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* HAL_RTC_MODULE_ENABLED */
+
+/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
diff --git a/cores/arduino/stm32/rtc.h b/cores/arduino/stm32/rtc.h
new file mode 100644
index 0000000000..bfa2d98ad0
--- /dev/null
+++ b/cores/arduino/stm32/rtc.h
@@ -0,0 +1,166 @@
+/**
+  ******************************************************************************
+  * @file    rtc.h
+  * @author  WI6LABS
+  * @version V1.0.0
+  * @date    12-December-2017
+  * @brief   Header for RTC driver
+  ******************************************************************************
+  * @attention
+  *
+  * <h2><center>&copy; COPYRIGHT(c) 2017 STMicroelectronics</center></h2>
+  *
+  * Redistribution and use in source and binary forms, with or without modification,
+  * are permitted provided that the following conditions are met:
+  *   1. Redistributions of source code must retain the above copyright notice,
+  *      this list of conditions and the following disclaimer.
+  *   2. Redistributions in binary form must reproduce the above copyright notice,
+  *      this list of conditions and the following disclaimer in the documentation
+  *      and/or other materials provided with the distribution.
+  *   3. Neither the name of STMicroelectronics nor the names of its contributors
+  *      may be used to endorse or promote products derived from this software
+  *      without specific prior written permission.
+  *
+  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+  *
+  ******************************************************************************
+  */
+
+/* Define to prevent recursive inclusion -------------------------------------*/
+#ifndef __RTC_H
+#define __RTC_H
+
+/* Includes ------------------------------------------------------------------*/
+#include "stm32_def.h"
+
+#ifdef HAL_RTC_MODULE_ENABLED
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+/* Exported types ------------------------------------------------------------*/
+typedef enum {
+  HOUR_FORMAT_12,
+  HOUR_FORMAT_24
+} hourFormat_t;
+
+typedef enum {
+  AM,
+  PM
+} hourAM_PM_t;
+
+/* See AN4579 Table 5 for possible values */
+typedef enum {
+  OFF_MSK = 0,
+  SS_MSK  = 1, /* MSK0 */
+  MM_MSK  = 2, /* MSK1 */
+  HH_MSK  = 4, /* MSK2 */
+  D_MSK   = 8, /* MSK3 */
+  /* NOTE: STM32 RTC can't assign a month or a year to an alarm. Those enum
+  are kept for compatibility but are ignored inside enableAlarm(). */
+  M_MSK   = 16,
+  Y_MSK   = 32
+} alarmMask_t;
+
+/* Clock source selection */
+typedef enum {
+  LSI_CLOCK,
+  LSE_CLOCK,
+  HSE_CLOCK
+} sourceClock_t;
+
+typedef void(*voidCallbackPtr)(void *);
+
+/* Exported constants --------------------------------------------------------*/
+
+#define HSE_RTC_MAX 1000000U
+
+#if !defined(STM32F1xx)
+#if !defined(RTC_PRER_PREDIV_S) || !defined(RTC_PRER_PREDIV_S)
+#error "Unknown Family - unknown synchronous prescaler"
+#endif
+#define PREDIVA_MAX (RTC_PRER_PREDIV_A >> RTC_PRER_PREDIV_A_Pos)
+#define PREDIVS_MAX (RTC_PRER_PREDIV_S >> RTC_PRER_PREDIV_S_Pos)
+#endif /* !STM32F1xx */
+
+/* Ultra Low Power High (ULPH) density */
+#if defined(STM32L100xBA) || defined (STM32L151xBA) || defined (STM32L152xBA) ||\
+    defined(STM32L100xC) || defined (STM32L151xC) || defined (STM32L152xC) ||\
+    defined (STM32L162xC) || defined(STM32L151xCA) || defined (STM32L151xD) ||\
+    defined (STM32L152xCA) || defined (STM32L152xD) || defined (STM32L162xCA) ||\
+    defined (STM32L162xD) || defined(STM32L151xE) || defined(STM32L151xDX) ||\
+    defined (STM32L152xE) || defined (STM32L152xDX) || defined (STM32L162xE) ||\
+    defined (STM32L162xDX)
+#define STM32L1_ULPH
+#endif
+
+#if defined(STM32F0xx) || defined(STM32L0xx)
+#define RTC_Alarm_IRQn RTC_IRQn
+#define RTC_Alarm_IRQHandler RTC_IRQHandler
+#endif
+
+#if defined(STM32F1xx) && !defined(IS_RTC_WEEKDAY)
+/* Compensate missing HAL definition */
+#define IS_RTC_WEEKDAY(WEEKDAY) (((WEEKDAY) == RTC_WEEKDAY_MONDAY)    || \
+                                 ((WEEKDAY) == RTC_WEEKDAY_TUESDAY)   || \
+                                 ((WEEKDAY) == RTC_WEEKDAY_WEDNESDAY) || \
+                                 ((WEEKDAY) == RTC_WEEKDAY_THURSDAY)  || \
+                                 ((WEEKDAY) == RTC_WEEKDAY_FRIDAY)    || \
+                                 ((WEEKDAY) == RTC_WEEKDAY_SATURDAY)  || \
+                                 ((WEEKDAY) == RTC_WEEKDAY_SUNDAY))
+
+/* F1 doesn't manage 12h format */
+#define IS_RTC_HOUR12(HOUR)      IS_RTC_HOUR24(HOUR)
+#endif /* !STM32F1xx && !IS_RTC_WEEKDAY */
+
+/* __HAL_RCC_GET_RTC_SOURCE is not defined for F2 and F4 */
+#ifndef __HAL_RCC_GET_RTC_SOURCE
+static uint32_t RTC_getSource(void) {
+  RCC_PeriphCLKInitTypeDef  *PeriphClkInit;
+  HAL_RCCEx_GetPeriphCLKConfig(PeriphClkInit);
+  return PeriphClkInit->RTCClockSelection;
+}
+#define __HAL_RCC_GET_RTC_SOURCE()  RTC_getSource()
+#endif
+
+/* Exported macro ------------------------------------------------------------*/
+/* Exported functions ------------------------------------------------------- */
+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_init(hourFormat_t format, sourceClock_t source);
+void RTC_DeInit(void);
+
+void RTC_SetTime(uint8_t hours, uint8_t minutes, uint8_t seconds, uint32_t subSeconds, hourAM_PM_t period);
+void RTC_GetTime(uint8_t *hours, uint8_t *minutes, uint8_t *seconds, uint32_t *subSeconds, hourAM_PM_t *period);
+
+void RTC_SetDate(uint8_t year, uint8_t month, uint8_t day, uint8_t wday);
+void RTC_GetDate(uint8_t *year, uint8_t *month, uint8_t *day, uint8_t *wday);
+
+void RTC_StartAlarm(uint8_t day, uint8_t hours, uint8_t minutes, uint8_t seconds, uint32_t subSeconds, hourAM_PM_t period, uint8_t mask);
+void RTC_StopAlarm(void);
+void RTC_GetAlarm(uint8_t *day, uint8_t *hours, uint8_t *minutes, uint8_t *seconds, uint32_t *subSeconds, hourAM_PM_t *period, uint8_t *mask);
+void attachAlarmCallback(voidCallbackPtr func, void *data);
+void detachAlarmCallback(void);
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif /* HAL_RTC_MODULE_ENABLED */
+
+#endif /* __RTC_H */
+
+/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
diff --git a/variants/DISCO_F100RB/stm32f1xx_hal_conf.h b/variants/DISCO_F100RB/stm32f1xx_hal_conf.h
index ae26e7b8a6..78f5c5cf4d 100644
--- a/variants/DISCO_F100RB/stm32f1xx_hal_conf.h
+++ b/variants/DISCO_F100RB/stm32f1xx_hal_conf.h
@@ -72,7 +72,7 @@
 /*#define HAL_PCD_MODULE_ENABLED*/
 /*#define HAL_PWR_MODULE_ENABLED*/
 #define HAL_RCC_MODULE_ENABLED
-/*#define HAL_RTC_MODULE_ENABLED*/
+#define HAL_RTC_MODULE_ENABLED
 /*#define HAL_SD_MODULE_ENABLED*/
 /*#define HAL_SMARTCARD_MODULE_ENABLED*/
 #define HAL_SPI_MODULE_ENABLED
diff --git a/variants/DISCO_L072CZ_LRWAN1/stm32l0xx_hal_conf.h b/variants/DISCO_L072CZ_LRWAN1/stm32l0xx_hal_conf.h
index 1ab533250f..df2b858ef0 100644
--- a/variants/DISCO_L072CZ_LRWAN1/stm32l0xx_hal_conf.h
+++ b/variants/DISCO_L072CZ_LRWAN1/stm32l0xx_hal_conf.h
@@ -59,7 +59,7 @@
 /*#define HAL_LCD_MODULE_ENABLED   */
 /*#define HAL_LPTIM_MODULE_ENABLED   */
 /*#define HAL_RNG_MODULE_ENABLED   */
-/*#define HAL_RTC_MODULE_ENABLED   */
+#define HAL_RTC_MODULE_ENABLED
 #define HAL_SPI_MODULE_ENABLED
 #define HAL_TIM_MODULE_ENABLED
 /*#define HAL_TSC_MODULE_ENABLED   */
diff --git a/variants/DISCO_L475VG_IOT/stm32l4xx_hal_conf.h b/variants/DISCO_L475VG_IOT/stm32l4xx_hal_conf.h
index 9d9c175ef7..e35f48aed9 100644
--- a/variants/DISCO_L475VG_IOT/stm32l4xx_hal_conf.h
+++ b/variants/DISCO_L475VG_IOT/stm32l4xx_hal_conf.h
@@ -86,7 +86,7 @@
 #define HAL_QSPI_MODULE_ENABLED
 #define HAL_RCC_MODULE_ENABLED
 /* #define HAL_RNG_MODULE_ENABLED */
-/* #define HAL_RTC_MODULE_ENABLED */
+#define HAL_RTC_MODULE_ENABLED
 #define HAL_SAI_MODULE_ENABLED
 /* #define HAL_SD_MODULE_ENABLED */
 /* #define HAL_SMARTCARD_MODULE_ENABLED */
diff --git a/variants/NUCLEO_F030R8/stm32f0xx_hal_conf.h b/variants/NUCLEO_F030R8/stm32f0xx_hal_conf.h
index 04e82c19c6..d455dc3986 100644
--- a/variants/NUCLEO_F030R8/stm32f0xx_hal_conf.h
+++ b/variants/NUCLEO_F030R8/stm32f0xx_hal_conf.h
@@ -68,7 +68,7 @@
 //#define HAL_PCD_MODULE_ENABLED
 //#define HAL_PWR_MODULE_ENABLED
 #define HAL_RCC_MODULE_ENABLED
-//#define HAL_RTC_MODULE_ENABLED
+#define HAL_RTC_MODULE_ENABLED
 //#define HAL_SMARTCARD_MODULE_ENABLED
 //#define HAL_SMBUS_MODULE_ENABLED
 #define HAL_SPI_MODULE_ENABLED
diff --git a/variants/NUCLEO_F091RC/stm32f0xx_hal_conf.h b/variants/NUCLEO_F091RC/stm32f0xx_hal_conf.h
index 801ba28da6..c7c47dcb91 100644
--- a/variants/NUCLEO_F091RC/stm32f0xx_hal_conf.h
+++ b/variants/NUCLEO_F091RC/stm32f0xx_hal_conf.h
@@ -68,7 +68,7 @@
 //#define HAL_PCD_MODULE_ENABLED
 //#define HAL_PWR_MODULE_ENABLED
 #define HAL_RCC_MODULE_ENABLED
-//#define HAL_RTC_MODULE_ENABLED
+#define HAL_RTC_MODULE_ENABLED
 //#define HAL_SMARTCARD_MODULE_ENABLED
 //#define HAL_SMBUS_MODULE_ENABLED
 #define HAL_SPI_MODULE_ENABLED
diff --git a/variants/NUCLEO_F103RB/stm32f1xx_hal_conf.h b/variants/NUCLEO_F103RB/stm32f1xx_hal_conf.h
index c7207581eb..9369936ed5 100644
--- a/variants/NUCLEO_F103RB/stm32f1xx_hal_conf.h
+++ b/variants/NUCLEO_F103RB/stm32f1xx_hal_conf.h
@@ -72,7 +72,7 @@
 /*#define HAL_PCD_MODULE_ENABLED*/
 /*#define HAL_PWR_MODULE_ENABLED*/
 #define HAL_RCC_MODULE_ENABLED
-/*#define HAL_RTC_MODULE_ENABLED*/
+#define HAL_RTC_MODULE_ENABLED
 /*#define HAL_SD_MODULE_ENABLED*/
 /*#define HAL_SMARTCARD_MODULE_ENABLED*/
 #define HAL_SPI_MODULE_ENABLED
diff --git a/variants/NUCLEO_F207ZG/stm32f2xx_hal_conf.h b/variants/NUCLEO_F207ZG/stm32f2xx_hal_conf.h
index 1f0e92e3f9..156dd264c6 100644
--- a/variants/NUCLEO_F207ZG/stm32f2xx_hal_conf.h
+++ b/variants/NUCLEO_F207ZG/stm32f2xx_hal_conf.h
@@ -69,7 +69,7 @@
 #define HAL_PWR_MODULE_ENABLED
 #define HAL_RCC_MODULE_ENABLED
 /*#define HAL_RNG_MODULE_ENABLED   */
-/*#define HAL_RTC_MODULE_ENABLED   */
+#define HAL_RTC_MODULE_ENABLED
 /*#define HAL_SD_MODULE_ENABLED   */
 #define HAL_SPI_MODULE_ENABLED
 #define HAL_TIM_MODULE_ENABLED
diff --git a/variants/NUCLEO_F302R8/stm32f3xx_hal_conf.h b/variants/NUCLEO_F302R8/stm32f3xx_hal_conf.h
index 9f389c875d..9585e0e819 100644
--- a/variants/NUCLEO_F302R8/stm32f3xx_hal_conf.h
+++ b/variants/NUCLEO_F302R8/stm32f3xx_hal_conf.h
@@ -74,7 +74,7 @@
 // #define HAL_PCD_MODULE_ENABLED
 // #define HAL_PWR_MODULE_ENABLED
 #define HAL_RCC_MODULE_ENABLED
-// #define HAL_RTC_MODULE_ENABLED
+#define HAL_RTC_MODULE_ENABLED
 // #define HAL_SDADC_MODULE_ENABLED
 // #define HAL_SMARTCARD_MODULE_ENABLED
 // #define HAL_SMBUS_MODULE_ENABLED
diff --git a/variants/NUCLEO_F303RE/stm32f3xx_hal_conf.h b/variants/NUCLEO_F303RE/stm32f3xx_hal_conf.h
index 5fbb6b1393..3a09bb6299 100644
--- a/variants/NUCLEO_F303RE/stm32f3xx_hal_conf.h
+++ b/variants/NUCLEO_F303RE/stm32f3xx_hal_conf.h
@@ -74,7 +74,7 @@
 // #define HAL_PCD_MODULE_ENABLED
 // #define HAL_PWR_MODULE_ENABLED
 #define HAL_RCC_MODULE_ENABLED
-// #define HAL_RTC_MODULE_ENABLED
+#define HAL_RTC_MODULE_ENABLED
 // #define HAL_SDADC_MODULE_ENABLED
 // #define HAL_SMARTCARD_MODULE_ENABLED
 // #define HAL_SMBUS_MODULE_ENABLED
diff --git a/variants/NUCLEO_F401RE/stm32f4xx_hal_conf.h b/variants/NUCLEO_F401RE/stm32f4xx_hal_conf.h
index 3dff96e9f6..c7eedbd2a9 100644
--- a/variants/NUCLEO_F401RE/stm32f4xx_hal_conf.h
+++ b/variants/NUCLEO_F401RE/stm32f4xx_hal_conf.h
@@ -76,7 +76,7 @@
 /* #define HAL_QSPI_MODULE_ENABLED   */
 #define HAL_RCC_MODULE_ENABLED
 /* #define HAL_RNG_MODULE_ENABLED   */
-/* #define HAL_RTC_MODULE_ENABLED   */
+#define HAL_RTC_MODULE_ENABLED
 /* #define HAL_SAI_MODULE_ENABLED   */
 /* #define HAL_SD_MODULE_ENABLED   */
 #define HAL_SPI_MODULE_ENABLED
diff --git a/variants/NUCLEO_F411RE/stm32f4xx_hal_conf.h b/variants/NUCLEO_F411RE/stm32f4xx_hal_conf.h
index 3dff96e9f6..c7eedbd2a9 100644
--- a/variants/NUCLEO_F411RE/stm32f4xx_hal_conf.h
+++ b/variants/NUCLEO_F411RE/stm32f4xx_hal_conf.h
@@ -76,7 +76,7 @@
 /* #define HAL_QSPI_MODULE_ENABLED   */
 #define HAL_RCC_MODULE_ENABLED
 /* #define HAL_RNG_MODULE_ENABLED   */
-/* #define HAL_RTC_MODULE_ENABLED   */
+#define HAL_RTC_MODULE_ENABLED
 /* #define HAL_SAI_MODULE_ENABLED   */
 /* #define HAL_SD_MODULE_ENABLED   */
 #define HAL_SPI_MODULE_ENABLED
diff --git a/variants/NUCLEO_F446RE/stm32f4xx_hal_conf.h b/variants/NUCLEO_F446RE/stm32f4xx_hal_conf.h
index e98ba0870d..4a4f6f2bbf 100644
--- a/variants/NUCLEO_F446RE/stm32f4xx_hal_conf.h
+++ b/variants/NUCLEO_F446RE/stm32f4xx_hal_conf.h
@@ -76,7 +76,7 @@
 /* #define HAL_QSPI_MODULE_ENABLED   */
 #define HAL_RCC_MODULE_ENABLED
 /* #define HAL_RNG_MODULE_ENABLED   */
-/* #define HAL_RTC_MODULE_ENABLED   */
+#define HAL_RTC_MODULE_ENABLED
 /* #define HAL_SAI_MODULE_ENABLED   */
 /* #define HAL_SD_MODULE_ENABLED   */
 #define HAL_SPI_MODULE_ENABLED
diff --git a/variants/NUCLEO_L031K6/stm32l0xx_hal_conf.h b/variants/NUCLEO_L031K6/stm32l0xx_hal_conf.h
index ac01cbf299..f5c9bee9fc 100644
--- a/variants/NUCLEO_L031K6/stm32l0xx_hal_conf.h
+++ b/variants/NUCLEO_L031K6/stm32l0xx_hal_conf.h
@@ -61,7 +61,7 @@
 /*#define HAL_LCD_MODULE_ENABLED   */
 /*#define HAL_LPTIM_MODULE_ENABLED   */
 /*#define HAL_RNG_MODULE_ENABLED   */
-/*#define HAL_RTC_MODULE_ENABLED   */
+#define HAL_RTC_MODULE_ENABLED
 #define HAL_SPI_MODULE_ENABLED
 #define HAL_TIM_MODULE_ENABLED
 /*#define HAL_TSC_MODULE_ENABLED   */
diff --git a/variants/NUCLEO_L053R8/stm32l0xx_hal_conf.h b/variants/NUCLEO_L053R8/stm32l0xx_hal_conf.h
index 69b47b742b..26b1b171f6 100644
--- a/variants/NUCLEO_L053R8/stm32l0xx_hal_conf.h
+++ b/variants/NUCLEO_L053R8/stm32l0xx_hal_conf.h
@@ -70,7 +70,7 @@
 #define HAL_PWR_MODULE_ENABLED
 #define HAL_RCC_MODULE_ENABLED
 // #define HAL_RNG_MODULE_ENABLED
-// #define HAL_RTC_MODULE_ENABLED
+#define HAL_RTC_MODULE_ENABLED
 #define HAL_SPI_MODULE_ENABLED
 #define HAL_TIM_MODULE_ENABLED
 // #define HAL_TSC_MODULE_ENABLED
diff --git a/variants/NUCLEO_L152RE/stm32l1xx_hal_conf.h b/variants/NUCLEO_L152RE/stm32l1xx_hal_conf.h
index 25299b213a..1932a2bfab 100644
--- a/variants/NUCLEO_L152RE/stm32l1xx_hal_conf.h
+++ b/variants/NUCLEO_L152RE/stm32l1xx_hal_conf.h
@@ -72,7 +72,7 @@
 /*#define HAL_PCD_MODULE_ENABLED*/
 #define HAL_PWR_MODULE_ENABLED
 #define HAL_RCC_MODULE_ENABLED
-/*#define HAL_RTC_MODULE_ENABLED*/
+#define HAL_RTC_MODULE_ENABLED
 /*#define HAL_SD_MODULE_ENABLED*/
 /*#define HAL_SMARTCARD_MODULE_ENABLED*/
 #define HAL_SPI_MODULE_ENABLED
diff --git a/variants/NUCLEO_L432KC/stm32l4xx_hal_conf.h b/variants/NUCLEO_L432KC/stm32l4xx_hal_conf.h
index 1adfa64bb6..e76e19cdbb 100644
--- a/variants/NUCLEO_L432KC/stm32l4xx_hal_conf.h
+++ b/variants/NUCLEO_L432KC/stm32l4xx_hal_conf.h
@@ -86,7 +86,7 @@
 /* #define HAL_QSPI_MODULE_ENABLED */
 #define HAL_RCC_MODULE_ENABLED
 /* #define HAL_RNG_MODULE_ENABLED */
-/* #define HAL_RTC_MODULE_ENABLED */
+#define HAL_RTC_MODULE_ENABLED
 /* #define HAL_SAI_MODULE_ENABLED */
 /* #define HAL_SD_MODULE_ENABLED */
 /* #define HAL_SMARTCARD_MODULE_ENABLED */
diff --git a/variants/NUCLEO_L476RG/stm32l4xx_hal_conf.h b/variants/NUCLEO_L476RG/stm32l4xx_hal_conf.h
index 1adfa64bb6..e76e19cdbb 100644
--- a/variants/NUCLEO_L476RG/stm32l4xx_hal_conf.h
+++ b/variants/NUCLEO_L476RG/stm32l4xx_hal_conf.h
@@ -86,7 +86,7 @@
 /* #define HAL_QSPI_MODULE_ENABLED */
 #define HAL_RCC_MODULE_ENABLED
 /* #define HAL_RNG_MODULE_ENABLED */
-/* #define HAL_RTC_MODULE_ENABLED */
+#define HAL_RTC_MODULE_ENABLED
 /* #define HAL_SAI_MODULE_ENABLED */
 /* #define HAL_SD_MODULE_ENABLED */
 /* #define HAL_SMARTCARD_MODULE_ENABLED */