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RM0440 Rev 4 1559/2126

RM0440 Real-time clock (RTC)

1592

Bits 31:17 Reserved, must be kept at reset value.

Bit 16 RECALPF: Recalibration pending Flag

The RECALPF status flag is automatically set to 1 when software writes to the RTC_CALR

are taken into account, this bit returns to 0. Refer to Re-calibration on-the-fly.

Bits 15:8 Reserved, must be kept at reset value.

Bit 7 INIT: Initialization mode

0: Free running mode

1: Initialization mode used to program time and date register (RTC_TR and RTC_DR), and

prescaler register (RTC_PRER). Counters are stopped and start counting from the new

value when INIT is reset.

Bit 6 INITF: Initialization flag

When this bit is set to 1, the RTC is in initialization state, and the time, date and prescaler

registers can be updated.

0: Calendar registers update is not allowed

1: Calendar registers update is allowed

Bit 5 RSF: Registers synchronization flag

This bit is set by hardware each time the calendar registers are copied into the shadow

registers (RTC_SSRx, RTC_TRx and RTC_DRx). This bit is cleared by hardware in

initialization mode, while a shift operation is pending (SHPF = 1), or when in bypass shadow

It is cleared either by software or by hardware in initialization mode.

0: Calendar shadow registers not yet synchronized

1: Calendar shadow registers synchronized

Bit 4 INITS: Initialization status flag

This bit is set by hardware when the calendar year field is different from 0 (Backup domain

reset state).

0: Calendar has not been initialized

1: Calendar has been initialized

Bit 3 SHPF: Shift operation pending

This flag is set by hardware as soon as a shift operation is initiated by a write to the

RTC_SHIFTR register. It is cleared by hardware when the corresponding shift operation has

been executed. Writing to the SHPF bit has no effect.

0: No shift operation is pending

1: A shift operation is pending

ST STM32G474 User Manual

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