Connectivity line devices: reset and clock control (RCC) RM0008
125/1128 DocID13902 Rev 15
8.1.3 Backup domain reset
The backup domain has two specific resets that affect only the backup domain (see
Figure 4).
A backup domain reset is generated when one of the following events occurs:
1. Software reset, triggered by setting the BDRST bit in the Backup domain control
register (RCC_BDCR).
2. V
DD
or V
BAT
power on, if both supplies have previously been powered off.
8.2 Clocks
Three different clock sources can be used to drive the system clock (SYSCLK):
• HSI oscillator clock
• HSE oscillator clock
• PLL clock
The devices have the following two secondary clock sources:
• 40 kHz low speed internal RC (LSI RC) which drives the independent watchdog and
optionally the RTC used for Auto-wakeup from Stop/Standby mode.
• 32.768 kHz low speed external crystal (LSE crystal) which optionally drives the real-
time clock (RTCCLK)
Each clock source can be switched on or off independently when it is not used, to optimize
power consumption.
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