RTC Internal Helpers

Functions
static void	rtc_set_write_protection (EN_STATUS_te en_status)
	Enables or disables write protection of the RTC registers.

Detailed Description

Function Documentation

rtc_set_write_protection()

void rtc_set_write_protection ( EN_STATUS_te en_status )

static

Enables or disables write protection of the RTC registers.

The RTC write protection key sequence is defined by the STM32F401RE reference manual:

• Disable (unlock): write 0xCA then 0x53 to RTC_WPR.
• Enable (lock): write any invalid key (0xFF) to RTC_WPR.

Must be called before and after any write to RTC configuration registers (RTC_TR, RTC_DR, RTC_CR, RTC_PRER, RTC_ISR).

Parameters

[in]

en_status

ENABLE to re-lock registers, DISABLE to unlock them.

Definition at line 186 of file stm32f401re_rtc.c.

                                                             {
    if(en_status == ENABLE) {
        RTC->RTC_WPR = 0xFF; // Any invalid key re-enables write protection
    }
    else if(en_status == DISABLE) {
        RTC->RTC_WPR = 0xCA; // First key
        RTC->RTC_WPR = 0x53; // Second key — unlocks write access
    }
}

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