bq3285ED/LD
2. Write new values to all the time, alarm, and
Programming the RTC
calendar locations.
The time-of-day, alarm, and calendar bytes can be writ-
ten in either the BCD or binary format (see Table 2).
3. Clear the UTI bit to allow update transfers.
On the next update cycle, the RTC updates all 10 bytes
in the selected format.
These steps may be followed to program the time, alarm,
and calendar:
1. Modify the contents of register B:
a. Write a 1 to the UTI bit to prevent trans-
fers between RTC bytes and user buffer.
b. Write the appropriate value to the data
format (DF) bit to select BCD or binary
format for all time, alarm, and calendar
bytes.
c.
Write the appropriate value to the hour
format (HF) bit.
Table 2. Time, Alarm, and Calendar Formats
Range
Binary-Coded
Decimal
Decimal
0–59
Binary
Address
RTC Bytes
0
1
2
3
Seconds
00H–3BH
00H–3BH
00H–3BH
00H–3BH
00H–59H
00H–59H
00H–59H
00H–59H
Seconds alarm
Minutes
0–59
0–59
Minutes alarm
0–59
01H–OCH AM;
81H–8CH PM
01H–12H AM;
81H–92H PM
Hours, 12-hour format
1–12
4
5
Hours, 24-hour format
0–23
1–12
00H–17H
00H–23H
01H–OCH AM;
81H–8CH PM
01H–12H AM;
81H–92H PM
Hours alarm, 12-hour format
Hours alarm, 24-hour format
Day of week (1=Sunday)
Day of month
0–23
1–7
00H–17H
01H–07H
01H–1FH
01H–0CH
00H–63H
01H-1FH
00H–23H
01H–07H
01H–31H
01H–12H
00H–99H
01–31H
6
7
1–31
1–12
0–99
1–31
8
Month
9
Year
D
Day of month alarm
July 1997
5
TI [ TEXAS INSTRUMENTS ]
