ST STM32F101 series Reference Manual

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RM0008 Low-, medium-, high- and XL-density reset and clock control (RCC)
122
7.3.9 Backup domain control register (RCC_BDCR)
Address offset: 0x20
Reset value: 0x0000 0000, reset by Backup domain Reset.
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 LSEON, LSEBYP, RTCSEL and RTCEN bits of the Backup domain control register
(RCC_BDCR) are in the Backup domain. As a result, after Reset, these bits are write-
protected and the DBP bit in the Power control register (PWR_CR) has to be set before
these can be modified. Refer to Section 5 on page 44 for further information. These bits are
only reset after a Backup domain Reset (see Section 7.1.3: Backup domain reset). Any
internal or external Reset will not have any effect on these bits.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Reserved
BDRST
rw
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RTC
EN
Reserved
RTCSEL[1:0]
Reserved
LSE
BYP
LSE
RDY
LSEON
rw rw rw rw r rw
Bits 31:17 Reserved, must be kept at reset value.
Bit 16 BDRST: Backup domain software reset
Set and cleared by software.
0: Reset not activated
1: Resets the entire Backup domain
Bit 15 RTCEN: RTC clock enable
Set and cleared by software.
0: RTC clock disabled
1: RTC clock enabled
Bits 14:10 Reserved, must be kept at reset value.
Bits 9:8 RTCSEL[1:0]: RTC clock source selection
Set by software to select the clock source for the RTC. Once the RTC clock source has been
selected, it cannot be changed anymore unless the Backup domain is reset. The BDRST bit
can be used to reset them.
00: No clock
01: LSE oscillator clock used as RTC clock
10: LSI oscillator clock used as RTC clock
11: HSE oscillator clock divided by 128 used as RTC clock
Bits 7:3 Reserved, must be kept at reset value.

ST STM32F101 series Specifications

General

Brand	ST
Model	STM32F101 series
Category	Computer Hardware
Language	English