RCC RTC Clock Configuration

Macros
#define	__HAL_RCC_RTC_CONFIG(__RTC_CLKSOURCE__)   MODIFY_REG(RCC->BDCR, RCC_BDCR_RTCSEL, (__RTC_CLKSOURCE__))
	Macro to configure the RTC clock (RTCCLK).
#define	__HAL_RCC_GET_RTC_SOURCE()   (READ_BIT(RCC->BDCR, RCC_BDCR_RTCSEL))
	Macro to get the RTC clock source.
#define	__HAL_RCC_RTC_ENABLE()   (*(__IO uint32_t *) RCC_BDCR_RTCEN_BB = ENABLE)
	Macro to enable the the RTC clock.
#define	__HAL_RCC_RTC_DISABLE()   (*(__IO uint32_t *) RCC_BDCR_RTCEN_BB = DISABLE)
	Macro to disable the the RTC clock.
#define	__HAL_RCC_BACKUPRESET_FORCE()   (*(__IO uint32_t *) RCC_BDCR_BDRST_BB = ENABLE)
	Macro to force the Backup domain reset.
#define	__HAL_RCC_BACKUPRESET_RELEASE()   (*(__IO uint32_t *) RCC_BDCR_BDRST_BB = DISABLE)
	Macros to release the Backup domain reset.

Macro Definition Documentation

__HAL_RCC_BACKUPRESET_FORCE

#define __HAL_RCC_BACKUPRESET_FORCE

(

)

(*(__IO uint32_t *) RCC_BDCR_BDRST_BB = ENABLE)

Note

This function resets the RTC peripheral (including the backup registers) and the RTC clock source selection in RCC_BDCR register.

__HAL_RCC_GET_RTC_SOURCE

#define __HAL_RCC_GET_RTC_SOURCE

(

)

(READ_BIT(RCC->BDCR, RCC_BDCR_RTCSEL))

Return values

The	clock source can be one of the following values: RCC_RTCCLKSOURCE_NO_CLK No clock selected as RTC clock RCC_RTCCLKSOURCE_LSE LSE selected as RTC clock RCC_RTCCLKSOURCE_LSI LSI selected as RTC clock RCC_RTCCLKSOURCE_HSE_DIV128 HSE divided by 128 selected as RTC clock

__HAL_RCC_RTC_CONFIG

#define __HAL_RCC_RTC_CONFIG

(

__RTC_CLKSOURCE__

)

MODIFY_REG(RCC->BDCR, RCC_BDCR_RTCSEL, (__RTC_CLKSOURCE__))

Note

As the RTC clock configuration bits are in the Backup domain and write access is denied to this domain after reset, you have to enable write access using the Power Backup Access macro before to configure the RTC clock source (to be done once after reset).

Once the RTC clock is configured it can't be changed unless the Backup domain is reset using __HAL_RCC_BACKUPRESET_FORCE() macro, or by a Power On Reset (POR).

Parameters

__RTC_CLKSOURCE__

specifies the RTC clock source. This parameter can be one of the following values: RCC_RTCCLKSOURCE_NO_CLK No clock selected as RTC clock RCC_RTCCLKSOURCE_LSE LSE selected as RTC clock RCC_RTCCLKSOURCE_LSI LSI selected as RTC clock RCC_RTCCLKSOURCE_HSE_DIV128 HSE divided by 128 selected as RTC clock

Note

If the LSE or LSI is used as RTC clock source, the RTC continues to work in STOP and STANDBY modes, and can be used as wakeup source. However, when the HSE clock is used as RTC clock source, the RTC cannot be used in STOP and STANDBY modes.

The maximum input clock frequency for RTC is 1MHz (when using HSE as RTC clock source).

__HAL_RCC_RTC_DISABLE

#define __HAL_RCC_RTC_DISABLE

(

)

(*(__IO uint32_t *) RCC_BDCR_RTCEN_BB = DISABLE)

Note

These macros must be used only after the RTC clock source was selected.

__HAL_RCC_RTC_ENABLE

#define __HAL_RCC_RTC_ENABLE

(

)

(*(__IO uint32_t *) RCC_BDCR_RTCEN_BB = ENABLE)

Note

These macros must be used only after the RTC clock source was selected.