RM0367 Rev 7 681/1043
RM0367 Real-time clock (RTC)
694
27.7.9 RTC write protection register (RTC_WPR)
Address offset: 0x24
Reset value: 0x0000 0000
27.7.10 RTC sub second register (RTC_SSR)
Address offset: 0x28
RTC domain reset value: 0x0000 0000
System reset: 0x0000 0000 when BYPSHAD = 0. Not affected when BYPSHAD = 1.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res.
1514131211109876543210
Res. Res. Res. Res. Res. Res. Res. Res. KEY[7:0]
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Bits 31:8 Reserved, must be kept at reset value.
Bits 7:0 KEY[7:0]: Write protection key
This byte is written by software.
Reading this byte always returns 0x00.
Refer to RTC register write protection for a description of how to unlock RTC register write
protection.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res.
1514131211109876543210
SS[15:0]
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Bits 31:16 Reserved, must be kept at reset value.
Bits 15:0 SS[15:0]: Sub second value
SS[15:0] is the value in the synchronous prescaler counter. The fraction of a second is given by
the formula below:
Second fraction = (PREDIV_S - SS) / (PREDIV_S + 1)
Note: SS can be larger than PREDIV_S only after a shift operation. In that case, the correct
time/date is one second less than as indicated by RTC_TR/RTC_DR.
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