
RM0453 Rev 2
RM0453
Real-time clock (RTC)
1049
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
register, indicating that the RTC_CALR register is blocked. When the new calibration settings
are taken into account, this bit returns to 0. Refer to
Bits 15:13 Reserved, must be kept at reset value.
Bits 12:10
BCDU[2:0]
: BCD update (BIN = 10 or 11)
In mixed mode when both BCD calendar and binary extended counter are used (BIN = 10 or
11), the calendar second is incremented using the SSR Least Significant Bits.
0x0: 1s calendar increment is generated each time SS[7:0] = 0
0x1: 1s calendar increment is generated each time SS[8:0] = 0
0x2: 1s calendar increment is generated each time SS[9:0] = 0
0x3: 1s calendar increment is generated each time SS[10:0] = 0
0x4: 1s calendar increment is generated each time SS[11:0] = 0
0x5: 1s calendar increment is generated each time SS[12:0] = 0
0x6: 1s calendar increment is generated each time SS[13:0] = 0
0x7: 1s calendar increment is generated each time SS[14:0] = 0
Bits 9:8
BIN[1:0]
: Binary mode
00: Free running BCD calendar mode (Binary mode disabled).
01: Free running Binary mode (BCD mode disabled)
10: Free running BCD calendar and Binary modes
11: Free running BCD calendar and Binary modes
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), plus BIN and BCDU fields. 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_SSR, RTC_TR and RTC_DR). This bit is cleared by hardware in initialization
mode, while a shift operation is pending (SHPF = 1), or when in bypass shadow register
mode (BYPSHAD = 1). This bit can also be cleared by software.
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