[RTC] Avoid reset time after low power mode

cores/arduino/board.h

@@ -6,6 +6,7 @@
 */
 #include "interrupt.h"
 #include "analog.h"
+#include "backup.h"
 #include "clock.h"
 #include "core_callback.h"
 #include "digital_io.h"

cores/arduino/stm32/backup.h

@@ -0,0 +1,136 @@
+/**
+  ******************************************************************************
+  * @file    backup.h
+  * @author  fpistm
+  * @brief   Header for backup domain driver
+  ******************************************************************************
+  * @attention
+  *
+  * Copyright (c) 2017 STMicroelectronics.
+  * All rights reserved.
+  *
+  * This software component is licensed by ST under BSD 3-Clause license,
+  * the "License"; You may not use this file except in compliance with the
+  * License. You may obtain a copy of the License at:
+  *                        opensource.org/licenses/BSD-3-Clause
+  *
+  ******************************************************************************
+  */
+
+/* Define to prevent recursive inclusion -------------------------------------*/
+#ifndef __BACKUP_H
+#define __BACKUP_H
+
+/* Includes ------------------------------------------------------------------*/
+#include "stm32_def.h"
+#include "stm32yyxx_ll_rtc.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Exported macro ------------------------------------------------------------*/
+#if (!defined(STM32F0xx) && !defined(STM32F3xx) && !defined(STM32L0xx) &&\
+  !defined(STM32L1xx) && !defined(STM32L4xx)) || defined(RTC_BACKUP_SUPPORT)
+#if !defined(STM32L412xx) && !defined(STM32L422xx)
+#define ENABLE_BACKUP_SUPPORT
+#endif
+#endif
+
+#if !defined(RTC_BKP_INDEX) && defined(ENABLE_BACKUP_SUPPORT)
+#define RTC_BKP_INDEX LL_RTC_BKP_DR1
+#else
+#define RTC_BKP_INDEX 0
+#endif
+#ifndef RTC_BKP_VALUE
+#define RTC_BKP_VALUE 0x32F2
+#endif
+
+
+/* Exported functions ------------------------------------------------------- */
+static inline void resetBackupRegister(void)
+{
+#ifdef HAL_PWR_MODULE_ENABLED
+  /*  Enable access to the RTC registers */
+  HAL_PWR_EnableBkUpAccess();
+  /**
+    *  Write twice the value to flush the APB-AHB bridge
+    *  This bit shall be written in the register before writing the next one
+    */
+  HAL_PWR_EnableBkUpAccess();
+#endif
+  __HAL_RCC_BACKUPRESET_FORCE();
+  __HAL_RCC_BACKUPRESET_RELEASE();
+}
+
+static inline void enableBackupRegister(void)
+{
+  /* Enable Power Clock */
+#ifdef __HAL_RCC_PWR_IS_CLK_DISABLED
+  if (__HAL_RCC_PWR_IS_CLK_DISABLED()) {
+    __HAL_RCC_PWR_CLK_ENABLE();
+  }
+#endif
+#ifdef HAL_PWR_MODULE_ENABLED
+  /* Allow access to Backup domain */
+  HAL_PWR_EnableBkUpAccess();
+#endif
+#ifdef __HAL_RCC_BKP_CLK_ENABLE
+  /* Enable BKP CLK enable for backup registers */
+  __HAL_RCC_BKP_CLK_ENABLE();
+#endif
+}
+
+static inline void disableBackupRegister(void)
+{
+#ifdef HAL_PWR_MODULE_ENABLED
+  /* Forbid access to Backup domain */
+  HAL_PWR_DisableBkUpAccess();
+#endif
+#ifdef __HAL_RCC_BKP_CLK_DISABLE
+  /* Disable BKP CLK enable for backup registers */
+  __HAL_RCC_BKP_CLK_DISABLE();
+#endif
+  /* Disable Power Clock */
+#ifdef __HAL_RCC_PWR_IS_CLK_DISABLED
+  if (!__HAL_RCC_PWR_IS_CLK_DISABLED()) {
+    __HAL_RCC_PWR_CLK_DISABLE();
+  }
+#endif
+}
+
+static inline void setBackupRegister(uint32_t index, uint32_t value)
+{
+#if defined(STM32F1xx)
+  LL_RTC_BKP_SetRegister(BKP, index, value);
+#else
+#ifdef ENABLE_BACKUP_SUPPORT
+  LL_RTC_BAK_SetRegister(RTC, index, value);
+#else
+  UNUSED(index);
+  UNUSED(value);
+#endif
+#endif
+}
+
+static inline uint32_t getBackupRegister(uint32_t index)
+{
+#if defined(STM32F1xx)
+  return LL_RTC_BKP_GetRegister(BKP, index);
+#else
+#ifdef ENABLE_BACKUP_SUPPORT
+  return LL_RTC_BAK_GetRegister(RTC, index);
+#else
+  UNUSED(index);
+  return 0;
+#endif
+#endif
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __BACKUP_H */
+
+/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

cores/arduino/stm32/clock.c

@@ -35,6 +35,7 @@
   *
   ******************************************************************************
   */
+#include "backup.h"
 #include "clock.h"
 #include "stm32yyxx_ll_cortex.h"
 
@@ -98,6 +99,8 @@ void enableClock(sourceClock_t source)
   RCC_OscInitTypeDef RCC_OscInitStruct = {0};
   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
 
+  enableBackupRegister();
+
   switch (source) {
     case LSI_CLOCK:
 #ifdef STM32WBxx
@@ -118,16 +121,6 @@ void enableClock(sourceClock_t source)
       }
       break;
     case LSE_CLOCK:
-      /* Enable Power Clock */
-#if !defined(STM32H7xx) && !defined(STM32WBxx)
-      if (__HAL_RCC_PWR_IS_CLK_DISABLED()) {
-        __HAL_RCC_PWR_CLK_ENABLE();
-      }
-#endif
-#ifdef HAL_PWR_MODULE_ENABLED
-      /* Allow access to Backup domain */
-      HAL_PWR_EnableBkUpAccess();
-#endif
       if (__HAL_RCC_GET_FLAG(RCC_FLAG_LSERDY) == RESET) {
 #ifdef __HAL_RCC_LSEDRIVE_CONFIG
         __HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);

cores/arduino/stm32/rtc.c

@@ -292,10 +292,14 @@ static void RTC_computePrediv(int8_t *asynch, int16_t *synch)
   * @param format: enable the RTC in 12 or 24 hours mode
   * @retval None
   */
-void RTC_init(hourFormat_t format, sourceClock_t source)
+void RTC_init(hourFormat_t format, sourceClock_t source, bool reset)
 {
   initFormat = format;
 
+  if (reset) {
+    resetBackupRegister();
+  }
+
   /* Init RTC clock */
   RTC_initClock(source);
 
@@ -323,19 +327,15 @@ void RTC_init(hourFormat_t format, sourceClock_t source)
 
   HAL_RTC_Init(&RtcHandle);
 
-  /*Sunday 1st January 2017*/
-  RTC_SetDate(17, 1, 1, 7);
-
-  /*at 0:0:0*/
-  RTC_SetTime(0, 0, 0, 0, HOUR_AM);
-
 #if !defined(STM32F1xx) && !defined(STM32F2xx) && !defined(STM32L1xx) || defined(STM32L1_ULPH)
   /* 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);
+  /* Ensure backup domain is enabled */
+  enableBackupRegister();
 }
 
 /**
@@ -349,6 +349,15 @@ void RTC_DeInit(void)
   callbackUserData = NULL;
 }
 
+/**
+  * @brief Check wether time is already set
+  * @retval True if set else false
+  */
+bool RTC_IsTimeSet(void)
+{
+  return (getBackupRegister(RTC_BKP_INDEX) == RTC_BKP_VALUE) ? true : false;
+}
+
 /**
   * @brief Set RTC time
   * @param hours: 0-12 or 0-23. Depends on the format used.
@@ -392,6 +401,7 @@ void RTC_SetTime(uint8_t hours, uint8_t minutes, uint8_t seconds, uint32_t subSe
 #endif /* !STM32F1xx */
 
     HAL_RTC_SetTime(&RtcHandle, &RTC_TimeStruct, RTC_FORMAT_BIN);
+    setBackupRegister(RTC_BKP_INDEX, RTC_BKP_VALUE);
   }
 }
 
@@ -453,6 +463,7 @@ void RTC_SetDate(uint8_t year, uint8_t month, uint8_t day, uint8_t wday)
     RTC_DateStruct.Date = day;
     RTC_DateStruct.WeekDay = wday;
     HAL_RTC_SetDate(&RtcHandle, &RTC_DateStruct, RTC_FORMAT_BIN);
+    setBackupRegister(RTC_BKP_INDEX, RTC_BKP_VALUE);
   }
 }
 

cores/arduino/stm32/rtc.h

@@ -40,6 +40,8 @@
 #define __RTC_H
 
 /* Includes ------------------------------------------------------------------*/
+#include <stdbool.h>
+#include "backup.h"
 #include "clock.h"
 
 #ifdef HAL_RTC_MODULE_ENABLED
@@ -135,8 +137,9 @@ 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_init(hourFormat_t format, sourceClock_t source);
+void RTC_init(hourFormat_t format, sourceClock_t source, bool reset);
 void RTC_DeInit(void);
+bool RTC_IsTimeSet(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);