Time Counter Group - Philips LPC2194 User Manual

Philips Semiconductors
ARM-based Microcontroller

TIME COUNTER GROUP

The time value consists of the eight counters shown in Tables 186 and 187. These counters can be read or written at the locations
shown in Table 187.
Table 186: Time Counter Relationships and Values
Counter
Second
Minute
Hour
Day of Month
Day of Week
Day of Year
Month
Year
Table 187: Time Counter registers
Address Name
0xE0024020 SEC
0xE0024024 MIN
0xE0024028 HOUR
0xE002402C DOM
0xE0024030 DOW
0xE0024034 DOY
0xE0024038 MONTH
0xE002403C YEAR
Notes:
1. These values are simply incremented at the appropriate intervals and reset at the defined overflow point. They are not
calculated and must be correctly initialized in order to be meaningful.
Leap Year Calculation
The RTC does a simple bit comparison to see if the two lowest order bits of the year counter are zero. If true, then the RTC
considers that year a leap year. The RTC considers all years evenly divisible by 4 as leap years. This algorithm is accurate from
the year 1901 through the year 2099, but fails for the year 2100, which is not a leap year. The only effect of leap year on the RTC
is to alter the length of the month of February for the month, day of month, and year counters.
Real Time Clock
Size Enabled by
6 Clk1 (see Figure 44)
6 Second
5 Minute
5 Hour
3 Hour
9 Hour
4 Day of Month
12 Month or Day of Year
Size
6 Seconds value in the range of 0 to 59.
6 Minutes value in the range of 0 to 59.
5 Hours value in the range of 0 to 23.
Day of month value in the range of 1 to 28, 29, 30, or 31 (depending
5
on the month and whether it is a leap year).
3 Day of week value in the range of 0 to 6.
9 Day of year value in the range of 1 to 365 (366 for leap years).
4 Month value in the range of 1 to 12.
12 Year value in the range of 0 to 4095.
LPC2119/2129/2194/2292/2294
Min value
0
0
0
1
0
1
1
0
Description
1
251
Preliminary User Manual
Maximum value
59
59
23
28,29,30, or 31
6
365 or 366 (for leap year)
12
4095
1
1
May 03, 2004
Access
R/W
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