
Reset and clock control (RCC)
RM0453
334/1454
RM0453 Rev 2
7.4.30 RCC
Backup
domain control register (RCC_BDCR)
Address offset: 0x090
Reset value: 0x0000 0000
Reset by Backup domain reset, except LSCOSEL, LSCOEN and BDRST that are reset only
by Backup domain power-on reset but not reset by wakeup from Standby and NRST pad.
Access: 0
≤
wait state
≤
3, word, half-word and byte access
Wait states are inserted in case of successive accesses to this register.
Note:
The bits of this register are outside of the V
CORE
domain. As a result, after Reset, these bits
are write-protected and the DBP bit in the
PWR control register 1 (PWR_CR1)
must be set
before these bits can be modified. Refer to
Section 6.1.2: Battery Backup domain
for further
information. These bits (except LSCOSEL, LSCOEN and BDRST) are only reset after a
Backup domain reset (see
Section 7.1.3: Backup domain reset
). Any internal or external
reset has no effect on these bits.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Res.
Res.
Res.
Res.
Res.
Res.
LSCO
SEL
LSCO
EN
Res.
Res.
Res.
Res.
Res.
Res.
Res.
BDRST
rw
rw
rw
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RTCEN
Res.
Res.
Res.
LSESY
SRDY
Res.
RTCSEL[1:0]
LSE
SYSEN
LSE
CSSD
LSE
CSSON
LSEDRV[1:0]
LSE
BYP
LSE
RDY
LSEON
rw
r
rw
rw
rw
r
rw
rw
rw
rw
r
rw
Bits 31:26 Reserved, must be kept at reset value.
Bit 25
LSCOSEL:
Low-speed clock output selection
This bit is set and cleared by software.
0: LSI clock selected
1: LSE clock selected
Bit 24
LSCOEN:
Low-speed clock output enable
This bit is set and cleared by software.
0: LSCO disabled
1: LSCO enabled
Bits 23:17 Reserved, must be kept at reset value.
Bit 16
BDRST:
Backup domain software reset
This bit is set and cleared by software.
0: Reset not activated
1: Entire Backup domain reset
Bit 15
RTCEN:
RTC kernel clock enable
This bit is set and cleared by software. The RTC APB bus clock is controlled by the
RTCAPBEN bit in the RCC_APB1ENR1 and RCC_C2APB1ENR1 registers and the
RTCAPBSMEN bit in the RCC_CnAPB1SMENR1and RCC_C2APB1SMENR1 registers.
0: RTC kernel clock disabled
1: RTC kernel clock enabled
Bits 14:12 Reserved, must be kept at reset value.