Rainbow Electronics DS1305 - Manual (Page 6)

DS1305
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Figure 2. RTC REGISTERS AND ADDRESS MAP
HEX ADDRESS
READ WRITE
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 RANGE
00H 80H 0 10-SEC SEC 00–59
01H 81H 0 10-MIN MIN 00–59
P 01–12 + P/A
12
A 02H 82H 0
24 10
10-HR HOURS
00–23
03H 83H 0 0 0 0 DAY 1–7
04H 84H 0 0 10-DATE DATE 1–31
05H 85H 0 0 10-MONTH MONTH 01–12
06H 86H 10 YEAR YEAR 00–99
— — ALARM 0 —
07H 87H M 10-SEC ALARM SEC ALARM 00–59
08H 88H M 10-MIN ALARM MIN ALARM 00–59
P
12
A
01–12 + P/A
09H 89H M
24 10
10 HR HOUR ALARM
00–23
0AH 8AH M 0 0 0 DAY ALARM 01–07
— — ALARM 1 —
0BH 8BH M 10-SEC ALARM SEC ALARM 00–59
0CH 8CH M 10-MIN ALARM MIN ALARM 00–59
P
12
A
01–12 + P/A
0DH 8DH M
24 10
10 HR HOUR ALARM
00–23
0EH 8EH M 0 0 0 DAY ALARM 01–07
0FH 8FH CONTROL REGISTER —
10H 90H STATUS REGISTER —
11H 91H TRICKLE CHARGER REGISTER —
12–1FH 92–9FH RESERVED —
20–7FH A0–FFH 96 BYTES USER RAM 00–FF
Note: Range for alarm registers does not include mask’m’ bits.
The DS1305 can be run in either 12-hour or 24-hour mode. Bit 6 of the hours register is defined as the
12- or 24-hour mode select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5 is the
AM/PM bit with logic high being PM. In the 24-hour mode, bit 5 is the second 10-hour bit (20 to 23
hours).
The DS1305 contains two time-of-day alarms. Time-of-day Alarm 0 can be set by writing to registers 87h
to 8Ah. Time-of-day Alarm 1 can be set by writing to registers 8Bh to 8Eh. The alarms can be
programmed (by the INTCN bit of the control register) to operate in two different modes; each alarm can
drive its own separate interrupt output or both alarms can drive a common interrupt output. Bit 7 of each
of the time-of-day alarm registers are mask bits (Table 1). When all of the mask bits are logic 0, a time-
of-day alarm only occurs once per week when the values stored in timekeeping registers 00h to 03h
match the values stored in the time-of-day alarm registers. An alarm is generated every day when bit 7 of
the day alarm register is set to a logic 1. An alarm is generated every hour when bit 7 of the day and hour
alarm registers is set to a logic 1. Similarly, an alarm is generated every minute when bit 7 of the day,
hour, and minute alarm registers is set to a logic 1. When bit 7 of the day, hour, minute, and seconds
alarm registers is set to a logic 1, alarm occurs every second.