DS1427

021798 2/2

Memory is organized into 16 pages of 256 bits each. An

additional scratch page is provided to validate data

before it is written into storage areas.

There are four function commands to address the

memory. Three commands are used to read, write, or

copy data to or from the scratch page and the storage

areas accordingly. All data is written to the scratch page

first, verified, and then copied to the appropriate storage

locations. The fourth command is used to read the con-

tents of the storage locations, the clock, elapsed timer,

alarm registers, or the configuration/status registers.

The real time clock keeps time in 1/256 second incre-

ments. This can be translated into seconds, minutes,

days, months or years. A read of the clock will return the

number of seconds after the reference date.

The

elapsed timer can be stopped or started based on the

contents of the configuration registers.

The configuration and status registers control the oper-

ating mode of the DS1427. Setting alarms and control-

ling interrupts for the clock and elapsed timer are user

selectable. Additional registers are used to control the

clock oscillator, elapsed timer triggers, and to provide

write protection for various memory locations.

DS1427 TIME iButton ORGANIZATION Figure 1

8-BIT CRC CODE

48-BIT SERIAL NUMBER

10000100

MSB

FAMILY CODE

0000h

01FFh

0200h

0201h

0202h

0206h

0207h

020Bh

020Ch

020Fh

0210h

0214h

0215h

0219h

021Ah

021Dh

512 Bytes NV SRAM

16 Pages

32 Bytes per Page

Configuration and Status Registers

Real Time Clock

Elapsed Timer

RTC Alarm

Elapsed Time Alarm

Reserved

Reserved