217
Philips Semiconductors
Preliminary User Manual
LPC2119/2129/2292/2294
ARM-based Microcontroller
TIME COUNTER GROUP
The time value consists of the eight counters shown in Tables 185 and 186. These counters can be read or written at the locations
shown in Table 186.
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.
Table 185: Time Counter Relationships and Values
Counter
Size
Enabled by
Min value
Maximum value
Second
6
Clk1 (see Figure 43)
0
59
Minute
6
Second
0
59
Hour
5
Minute
0
23
Day of Month
5
Hour
1
28,29,30, or 31
Day of Week
3
Hour
0
6
Day of Year
9
Hour
1
365 or 366 (for leap year)
Month
4
Day of Month
1
12
Year
12
Month or Day of Year
0
4095
Table 186: Time Counter registers
Address
Name
Size
Description
Access
0xE0024020
SEC
6
Seconds value in the range of 0 to 59.
R/W
0xE0024024
MIN
6
Minutes value in the range of 0 to 59.
R/W
0xE0024028
HOUR
5
Hours value in the range of 0 to 23.
R/W
0xE002402C
DOM
5
Day of month value in the range of 1 to 28, 29, 30, or 31 (depending
on the month and whether it is a leap year).
R/W
0xE0024030
DOW
3
Day of week value in the range of 0 to 6.
R/W
0xE0024034
DOY
9
Day of year value in the range of 1 to 365 (366 for leap years).
R/W
0xE0024038
MONTH
4
Month value in the range of 1 to 12.
R/W
0xE002403C
YEAR
12
Year value in the range of 0 to 4095.
R/W