1 files changed, 45 insertions, 2 deletions

diff --git a/stmhal/rtc.c b/stmhal/rtc.c
index 7a89d93e71..f58aa92733 100644
--- a/stmhal/rtc.c
+++ b/stmhal/rtc.c
@@ -161,7 +161,7 @@ void rtc_init(void) {
 }
 #endif
 
-static void RTC_CalendarConfig(void);
+STATIC void RTC_CalendarConfig(void);
 
 void rtc_init(void) {
     RTCHandle.Instance = RTC;
@@ -211,7 +211,7 @@ void rtc_init(void) {
     }
 }
 
-static void RTC_CalendarConfig(void) {
+STATIC void RTC_CalendarConfig(void) {
     // set the date to 1st Jan 2014
     RTC_DateTypeDef date;
     date.Year = 14;
@@ -242,6 +242,49 @@ static void RTC_CalendarConfig(void) {
     HAL_RTCEx_BKUPWrite(&RTCHandle, RTC_BKP_DR0, 0x32f2);
 }
 
+/*
+  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_BDCR register are set to their reset values.
+*/
+void HAL_RTC_MspInit(RTC_HandleTypeDef *hrtc) {
+    RCC_OscInitTypeDef        RCC_OscInitStruct;
+    RCC_PeriphCLKInitTypeDef  PeriphClkInitStruct;
+
+    /* To change the source clock of the RTC feature (LSE, LSI), You have to:
+       - Enable the power clock using __PWR_CLK_ENABLE()
+       - Enable write access using HAL_PWR_EnableBkUpAccess() function before to
+         configure the RTC clock source (to be done once after reset).
+       - Reset the Back up Domain using __HAL_RCC_BACKUPRESET_FORCE() and
+         __HAL_RCC_BACKUPRESET_RELEASE().
+       - Configure the needed RTc clock source */
+
+    // set LSE as RTC clock source
+    RCC_OscInitStruct.OscillatorType =  RCC_OSCILLATORTYPE_LSI | RCC_OSCILLATORTYPE_LSE;
+    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
+    RCC_OscInitStruct.LSEState = RCC_LSE_ON;
+    RCC_OscInitStruct.LSIState = RCC_LSI_OFF;
+    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
+        //Error_Handler();
+        return;
+    }
+
+    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
+    PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
+    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
+        //Error_Handler();
+        return;
+    }
+
+    // enable RTC peripheral clock
+    __HAL_RCC_RTC_ENABLE();
+}
+
+void HAL_RTC_MspDeInit(RTC_HandleTypeDef *hrtc) {
+    __HAL_RCC_RTC_DISABLE();
+}
+
 /******************************************************************************/
 // Micro Python bindings