Epson RA8804 CE, Applications Manual

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RA8804 CE
Page - 9 ETM60E-02
8.2.2. Calendar counter (WEEK - YEAR)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
03 WEEK

6 5 4 3 2 1 0

“o” indicates write-protected bits. A zero is always read from these bits.
1) Day of the WEEK counter

The day (of the week) is indicated by 7 bits, bit 0 to bit 6.

The day data values are counted as follows: Day 01h

Day 02h

Day 04h

Day 08h

Day
10h

Day 20h

Day 40h

Day 01h

Day 02h, etc.

The correspondence between days and count values is shown below.
WEEK bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 Day Data [h]
Write/Read
0 0 0 0 0 0 0 1 Sunday 01 h
0 0 0 0 0 0 1 0 Monday 02 h
0 0 0 0 0 1 0 0 Tuesday 04 h
0 0 0 0 1 0 0 0 Wednesday 08 h
0 0 0 1 0 0 0 0 Thursday 10 h
0 0 1 0 0 0 0 0 Friday 20 h
0 1 0 0 0 0 0 0 Saturday 40 h
Write prohibit

Do not set
“1” to more than one day at the same time.
Also, note with caution that any setting other than the
seven shown above should not be made as it may
interfere with normal operation.
 
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
04 DAY
 
20 10 8 4 2 1
05 MONTH
  
10 8 4 2 1
06 YEAR 80 40 20 10 8 4 2 1

“o” indicates write-protected bits. A zero is always read from these bits.

The auto calendar function updates all dates, months, and years from January 1, 00 to December 31, 99.

The data format is BCD format. For example, a date register value of
“0011 0001” indicates the 31st.

Note with caution that writing non-existent date data may interfere with normal operation of the calendar
counter.
2) Date counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
04 DAY
 
20 10 8 4 2 1

The updating of dates by the date counter varies according to the month setting.

A leap year is set whenever the year value is a multiple of four (such as 04, 08, 12, 88, 92, or 96). In
February of a leap year, the counter counts dates from
“01”, “02”, “0”3, to “28”, “29”, “01”, etc.
DAY Month Date update pattern
Write/Read
1, 3, 5, 7, 8, 10, or 12 01, 02, 03

30, 31, 01

4, 6, 9, or 11
01, 02, 03

30, 01, 02

February in normal year 01, 02, 03

28, 01, 02

February in leap year 01, 02, 03

28, 29, 01

3) Month counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
05 MONTH
  
10 8 4 2 1

The month counter counts from 01 (January), 02 (February), and up to 12 (December), then starts again
at 01 (January).
4) Year counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
06 YEAR Y80 Y40 Y20 Y10 Y8 Y4 Y2 Y1

The year counter counts from 00, 01, 02 and up to 99, then starts again at 00.

Any year that is a multiple of four (04, 08, 12, 88, 92, 96, etc.) is handled as a leap year.