RTC – 4553AC
Page - 9
MQ - 342 - 01
8.2. Register Description
8.2.1. Time/Calendar Counter Registers
· In normal mode (CNTR = "0"), the counter is incremented by a write operation.
(1) Second digit counter
Counts values from 0 to 59. The counter can be read and incremented. When the second digit counter is
incremented, fractions below full seconds are reset. Therefore a carry occurs 1 second after the increment
operation is finished.
A3 A2 A1 A0
Name
D3 D2 D1 D0 Register
contents
0 0 0 0 S1
S
8
S
4
S
2
S
1
1-second digit counter
0 0 0 1
S10
0 S
40
S
20
S
10
10-second digit
counter
(2) Minute digit counter
A3 A2 A1 A0
Name
D3 D2 D1 D0 Register
contents
0 0 1 0
MI1
mi
8
mi
4
mi
2
mi
1
1-minute digit counter
0 0 1 1
MI10
0
mi
40
mi
20
mi
10
10-minute digit counter
Counts values from 0 to 59. The counter can be read and incremented.
(3) Hour digit counter
A3 A2 A1 A0
Name
D3 D2 D1 D0 Register
contents
0 1 0 0 H1
h
8
h
4
h
2
h
1
1-minute digit counter
0 1 0 1
H10
PM/AM
0 h
20
h
10
10-minute digit counter
Counts values from 0 to 23. The counter can be read, and the 1-hour digit counter can be incremented.
(The 10-hour digit counter cannot be incremented.)
D0 in the control register 1 sets the 12-hour/24-hour display format.
24/12 bit
Displayed time
0 (12-hour format)
AM 12:00 to AM 11:59, PM 12:00 to PM 11:59
1 (24-hour format)
AM 00:00 to AM 11:59, PM 12:00 to PM 23:59
* PM/AM bit: This bit is output also when 24-hour format is selected.
* Time keeping is not affected also when the 12-hour/24- hour format is switched during clock operation.
(4) Day of the week digit counter
A3 A2 A1 A0
Name
D3 D2 D1 D0 Register
contents
0 1 1 0 W 0 w
4
w
2
w
1
Day of the week digit
counter
Counts values from 0 to 6. The counter can be read and incremented. The correspondence between count
value and day of the week is set by the user.
Example
Data
0 1 2 3 4 5 6
Coded day of the week
Sun.
Mon.
Tue.
Wed.
Thu.
Fri.
Sat.
(5) Day digit counter
A3 A2 A1 A0
Name
D3 D2 D1 D0 Register
contents
0 1 1 1 D1
d
8
d
4
d
2
d
1
1-day digit counter
1 0 0 0
D10
0 0 d
20
d
10
10-day digit counter
The counter value is different depending on the month.
(a) For long months (1, 3, 5, 7, 8, 10, 12), the counter counts values from 1 to 31. The counter can be read
and incremented.
(b) For short months (4, 6, 9, 11), the counter counts values from 1 to 30. The counter can be read and
incremented.
(c) For February, the counter counts values from 1 to 29 if it is a leap year and from 1 to 28 in other years.
The counter can be read and incremented.
(6) Month digit counter
A3 A2 A1 A0
Name
D3 D2 D1 D0 Register
contents
1 0 0 1
MO1
mo
8
mo
4
mo
2
mo
1
1-month digit counter
1 0 1 0
MO10
0 0 0
mo
10
10-month digit counter
Counts values from 1 to 12. The counter can be read and incremented.
(7) Year digit counter
A3 A2 A1 A0
Name
D3 D2 D1 D0 Register
contents
1 0 1 1 Y1
y
8
y
4
y
2
y
1
1-year digit counter
1 1 0 0
Y10
y
80
y
40
y
20
y
10
10-year digit counter
Counts values from 0 to 99 for the last two digits of the year. The counter can be read and incremented. Until
2099, leap year compensation is automatically provided. ('92, '96, '00, '04, '08, '12, '16, '20 ... are leap years.)
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