Samsung S3C2451X User Manual page 334

Real Time Clock
14.3 Real Time Clock Operation Description
TICNT
XTIrtc
XTOrtc
14.3.1 Leap Year Generator
The leap year generator can determine the last date of each month out of 28, 29, 30, or 31, based on data from
BCDDAY, BCDMON, and BCDYEAR. This block considers leap year in deciding on the last date. An 8-bit
counter can only represent 2 BCD digits, therefore it cannot decide whether "00" year (the year with its last two
digits zeros) is a leap year or not. For example, it cannot discriminate between 1900 and 2000. To solve this
problem, the RTC block in S3C2451 has hard-wired logic to support the leap year in 2000. Note 1900 is not leap
year while 2000 is leap year in general Gregorian calendar. Therefore, two digits of 00 in S3C2451 denote 2000,
not 1900. So, RTC in S3C2451 supports from 1901 to 2099.
14-2
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
Time Tick Generator
32KHz~1Hz
2 Clock
15
Divider
1 Hz
Control
Register
RTCCON
Figure 14-1. Real Time Clock Block Diagram
RTCRST
Reset
Register
SEC MIN HOUR
Alarm Generator
ALMWKUP
S3C2451
RISC MICROPROCESSOR
Leap Year Generator
DATE DAY MON
ALMINT
TICWKUP
TICINT
YEAR
RTCALM