bq3285
c.
Write the appropriate value to the hour
format (HF) bit.
Programming the RTC
The time-of-day, alarm, and calendar bytes can be writ-
ten in either the BCD or binary format (see Table 2).
2. Write new values to all the time, alarm, and
calendar locations.
3. Clear the UTI bit to allow update transfers.
These steps may be followed to program the time, alarm,
and calendar:
On the next update cycle, the RTC updates all 10 bytes
in the selected format.
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.
Table 2. Time, Alarm, and Calendar Formats
Range
Decimal
0–59
Binary
Binary-Coded Decimal
00H–59H
Address
RTC Bytes
0
1
2
3
Seconds
00H–3BH
00H–3BH
00H–3BH
00H–3BH
Seconds alarm
Minutes
0–59
00H–59H
0–59
00H–59H
Minutes alarm
0–59
00H–59H
01H–OCH AM;
81H–8CH PM
01H–12H AM;
81H–92H PM
Hours, 12-hour format
Hours, 24-hour format
Hours alarm, 12-hour format
1–12
0–23
4
5
00H–17H
00H–23H
01H–OCH AM;
81H–8CH PM
01H–12H AM;
81H–92H PM
1–12
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
00H–23H
01H–07H
01H–31H
01H–12H
00H–99H
6
7
8
9
1–31
1–12
0–99
Month
Year
Jan. 1999 E
5
TI [ TEXAS INSTRUMENTS ]
