Ameba-D User Manual
User Manual All information provided in this document is subject to legal disclaimers. © REALTEK 2019. All rights reserved.
242
1
Disable the RTC registers write protection
Write ‘0xCA’ and then ‘0x53’ into the RTC_WPR
register
RTC registers can be modified
2
Check that the RTC_CALIBR register can
be updated
Poll the RECALPF bit until it is 0 in RTC_ISR
register
-
3
Configure the calibration parameter
Configure RTC_CALIBR register
-
4
Enable the RTC registers Write protection
Write ‘0xFF’ into the RTC_WPR register
RTC registers can no longer be
modified
Note:
Calibration can also be configured in the initialization mode.
The calibration parameter isn’t used immediately. Hardware automatically reloads the new calibration parameter at the end of
calibration period.
11.4.4
Daylight Saving Time
The daylight saving time management is performed through bits SUB1H, ADD1H, and BKP of the RTC_CR register.
Using SUB1H or ADD1H, the software can subtract or add one hour to the calendar in one single operation without going through the
initialization procedure.
In addition, the software can use the BKP bit to memorize this operation.
It is recommended not to change the hour during the calendar hour increment, because hardware can handle this condition. if this condition
occurs, hardware delays the SUB1H or ADD1H operation for one second.
In the U.S., 2:00 am is originally chosen as the changeover time because it is practical and minimized disruption. Most people are at home and
this is the time when the fewest trains are running. It is late enough to minimally affect bars and restaurants, and it prevents the day from
switching to yesterday, which is confusing. It is early enough that the entire continental U.S. switches by daybreak, and the changeover occurs
before most early shift workers and early churchgoers are affected. (http://www.webexhibits.org/daylightsaving/b.html)
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2019-05-15 10:08:03