DS2404 - EconoRAM time chip

NAME SYNOPSIS FAMILY CODE SPECIAL PROPERTIES alarm auto date delay interval memory pages/page.0 ... pages/page.15 pages/page.ALL readonly/[memory|clock|interval|cycle] running set_alarm start trigger/[cycle,date,interval,udate,uinterval] udate uinterval STANDARD PROPERTIES ALARMS DESCRIPTION DS1427 DS1994 DS2404 DS2404S Chips iButtons ADDRESSING DATASHEET SEE ALSO AVAILABILITY AUTHOR

NAME

DS2404 − EconoRAM time chip
DS2404S

− Dual port memory plus time

	DS1994		− 4k plus time iButton
	DS1427		− Time iButton

SYNOPSIS

Real time clock, 4kbit memory. 3-wire interface, too.

FAMILY CODE

	04		DS2404 DS1994
	84		DS1427 DS2404S

SPECIAL PROPERTIES

alarm

read-write, unsigned integer (0-111)
Alarm state of the DS2404 (3) triggered by time or counter events. Reading the alarm state clears the alarm.
The alarm value is of the form CIR, where:

cycle counter alarm

0 no
1 yes

interval timer alarm

0 no
1 yes

real-time clock alarm

0 no
1 yes

auto

read-write, yes-no
Flag for mode of interval counter operation. 0=manual 1=auto
See the datasheet for details.

date

read-write, ascii
26 character date representation of the udate value. Increments once per second while running
Actual internal representation has higher precision.
Cannot be altered if readonly/clock is set.
Setting date to a null string will put the current system time.
Accepted date formats are:
Sat[urday] March 12 12:23:59 2001
Apr[il] 4 9:34:56 2002
3/23/04 23:34:57
current locale setting (your system’s format)

delay

read-write, yes-no
Flag for adding a delay to cycle counter. 0=short 1-long
See the datasheet under "IDEL" for details.

interval

read-write, date
Interval timer value, represented as a date string. More typically will be used as uinterval to read the actual elapsed seconds.

memory

read-write, binary
512 bytes of memory. The readonly/memory flag prevents further change.

pages/page.0 ... pages/page.15 pages/page.ALL

read-write, yes-no
Memory is split into 16 pages of 32 bytes each. The readonly/memory flag prevents further change. ALL is an aggregate of the pages. Each page is accessed sequentially.

readonly/[memory|clock|interval|cycle]

read-write, yes-no
Permanently protect part of the chip’s function from alteration.
readonly/memory

page.X and memory

readonly/clock

date and udate

readonly/interval

interval

readonly/cycle

cycle

running

read-write, yes-no
State of the clock. 0=off 1=running.

set_alarm

read-write, unsigned integer (0-111)
Which of the alarm triggers are enabled in the DS2404 (3)
The set_alarm value is of the form CIR, where:

cycle counter alarm

0 no
1 yes

interval timer alarm

0 no
1 yes

real-time clock alarm

0 no
1 yes

start

read-write, yes-no
Flag for starting the interval counter operation if not in auto mode. 0=stop 1=start
See the datasheet for details.

trigger/[cycle,date,interval,udate,uinterval]

read-write,varies
Target value that will trigger the alarm if the corresponding set_alarm field is set.
The format is the same as the similarly named field (i.e. date for trigger/date )

udate

read-write, unsigned integer
Time represented as a number. udate increments once per second, while running is on.
Usually set to unix time standard: number of seconds since Jan 1, 1970. The date field will be the unix representation of udate and setting either will change the other.

uinterval

read-write, unsigned interval
Similar to the udate field, except corresponds to the interval value.

STANDARD PROPERTIES

ALARMS

None implemented.

DESCRIPTION

DS1427 DS1994 DS2404 DS2404S

The DS1427 (3), DS1994 (3), DS2404 (3), and DS2404S (3) family of 1-wire devices includes clock functions, with timers, memory, counters and alarms. It is possible to write-protect regians of memory. Uses include software or hardware timing and control.

Chips

Both the DS2404 (3) and DS2404S (3) have 1-wire and 3-wire interfaces, which might be useful for transferring data between the 2 buses. They act as a passive slave to both buses. The DS2404 (3) and DS2404S (3) require an external source of power and an external crystal. They also offer a reset and 1HZ clock pin.

iButtons

Both the DS1427 and DS1994 offer the memory, alarms, and clock function in iButton format. Because the iButton is a complete sealed package, battery and crystal are internal. Everything is access via the 1-wire interface.