DS3234 datasheet(13/21 Pages) MAXIM

13 / 21 page

Alarms

The DS3234 contains two time-of-day/date alarms. Alarm

1 can be set by writing to registers 07h to 0Ah. Alarm 2

can be set by writing to registers 0Bh to 0Dh. The alarms

can be programmed (by the alarm enable and INTCN

bits of the control register) to activate the INT/SQW output

on an alarm match condition. Bit 7 of each of the time-of-

day/date alarm registers are mask bits (Table 2). When all

the mask bits for each alarm are logic 0, an alarm only

occurs when the values in the timekeeping registers

match the corresponding values stored in the time-of-

day/date alarm registers. The alarms can also be pro-

grammed to repeat every second, minute, hour, day, or

date. Table 2 shows the possible settings. Configurations

not listed in the table will result in illogical operations.

The DY/DT bits (bit 6 of the alarm day/date registers)

control whether the alarm value stored in bits 0 to 5 of

that register reflects the day of the week or the date of

the month. If DY/DT is written to logic 0, the alarm will

be the result of a match with date of the month. If

DY/DT is written to logic 1, the alarm will be the result of

a match with day of the week.

When the RTC register values match alarm register set-

tings, the corresponding Alarm Flag ‘A1F’ or ‘A2F’ bit is

set to logic 1. If the corresponding Alarm Interrupt

Enable ‘A1IE’ or ‘A2IE’ is also set to logic 1 and the

INTCN bit is set to logic 1, the alarm condition activates

the INT/SQW signal. The match is tested on the once-

per-second update of the time and date registers.

Table 2. Alarm Mask Bits

ALARM 1 REGISTER MASK BITS (BIT 7)

DY/DT

A1M4

A1M3

A1M2

A1M1

ALARM RATE

Alarm once per second

Alarm when seconds match

Alarm when minutes and seconds match

Alarm when hours, minutes, and seconds match

Alarm when date, hours, minutes, and seconds match

Alarm when day, hours, minutes, and seconds match

ALARM 2 REGISTER MASK BITS (BIT 7)

DY/DT

A2M4

A2M3

A2M2

ALARM RATE

Alarm once per minute (00 seconds of every minute)

Alarm when minutes match

Alarm when hours and minutes match

Alarm when date, hours, and minutes match

Alarm when day, hours, and minutes match

Extremely Accurate SPI Bus RTC with

Integrated Crystal and SRAM

____________________________________________________________________

DS3234 Datasheet(PDF) 13 Page - Maxim Integrated Products

DS3234 Datasheet(HTML) 13 Page - Maxim Integrated Products

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Datasheet Download

Link URL