Ubuntu Manpage: DS2404 - EconoRAM time chip

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.

       04.XXXXXXXXXXXX  /  alarm  |  auto  |  cycle | date | delay | interval | memory | pages/page.[0-15|ALL] |
       readonly/[memory|clock|cycle|interval]       |       memory       |        pages/page.[0-15|ALL]        |
       readonly/[memory|clock|cycle|interval]      |      running      |      set_alarm      |      start      |
       trigger/[cycle,date,interval,udate,uinterval] | udate | uinterval | address |  crc8  |  id  |  locator  |
       r_address | r_id | r_locator | type

       84.XXXXXXXXXXXX  /  alarm  |  auto  |  cycle | date | delay | interval | memory | pages/page.[0-15|ALL] |
       readonly/[memory|clock|cycle|interval]      |      running      |      set_alarm      |      start      |
       trigger/[cycle,date,interval,udate,uinterval] | udate | uinterval | address | crc8 | id | present | type

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:

C cycle counter alarm
0 no
1 yes

I interval timer alarm
0 no
1 yes

R 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:

C cycle counter alarm
0 no
1 yes

I interval timer alarm
0 no
1 yes

R 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

address
r_address
read-only, ascii
The entire 64-bit unique ID. Given as upper case hexadecimal digits (0-9A-F).
address starts with the family code
r address is the address in reverse order, which is often used in other applications and labeling.

crc8
read-only, ascii
The 8-bit error correction portion. Uses cyclic redundancy check. Computed from the preceding 56 bits of
the unique ID number. Given as upper case hexadecimal digits (0-9A-F).

family
read-only, ascii
The 8-bit family code. Unique to each type of device. Given as upper case hexadecimal digits (0-9A-F).

id
r_id
read-only, ascii
The 48-bit middle portion of the unique ID number. Does not include the family code or CRC. Given as
upper case hexadecimal digits (0-9A-F).
r id is the id in reverse order, which is often used in other applications and labeling.

locator
r_locator
read-only, ascii
Uses an extension of the 1-wire design from iButtonLink company that associated 1-wire physical
connections with a unique 1-wire code. If the connection is behind a Link Locator the locator will show a
unique 8-byte number (16 character hexadecimal) starting with family code FE.
If no Link Locator is between the device and the master, the locator field will be all FF.
r locator is the locator in reverse order.

present (DEPRECATED)
read-only, yes-no
Is the device currently present on the 1-wire bus?

type
read-only, ascii
Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging (iButton vs chip) will not be
distiguished.

ALARMS

       None implemented.

DESCRIPTION

1-Wire
1-wire is a wiring protocol and series of devices designed and manufactured by Dallas Semiconductor, Inc.
The bus is a low-power low-speed low-connector scheme where the data line can also provide power.

Each device is uniquely and unalterably numbered during manufacture. There are a wide variety of devices,
including memory, sensors (humidity, temperature, voltage, contact, current), switches, timers and data
loggers. More complex devices (like thermocouple sensors) can be built with these basic devices. There
are also 1-wire devices that have encryption included.

The 1-wire scheme uses a single bus master and multiple slaves on the same wire. The bus master initiates
all communication. The slaves can be individually discovered and addressed using their unique ID.

Bus masters come in a variety of configurations including serial, parallel, i2c, network or USB adapters.

OWFS design
OWFS is a suite of programs that designed to make the 1-wire bus and its devices easily accessible. The
underlying principle is to create a virtual filesystem, with the unique ID being the directory, and the
individual properties of the device are represented as simple files that can be read and written.

Details of the individual slave or master design are hidden behind a consistent interface. The goal is to
provide an easy set of tools for a software designer to create monitoring or control applications. There
are some performance enhancements in the implementation, including data caching, parallel access to bus
masters, and aggregation of device communication. Still the fundemental goal has been ease of use,
flexibility and correctness rather than speed.

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 busses. 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.

ADDRESSING

       All 1-wire devices are factory assigned a unique 64-bit address. This address is of the form:

       Family Code
              8 bits

       Address
              48 bits

       CRC    8 bits

       Addressing under OWFS is in hexadecimal, of form:

              01.123456789ABC

       where 01 is an example 8-bit family code, and 12345678ABC is an example 48 bit address.

       The dot is optional, and the CRC code can included. If included, it must be correct.

DATASHEET

       http://pdfserv.maxim-ic.com/en/ds/DS2404.pdf
       http://pdfserv.maxim-ic.com/en/ds/DS2404S-C01.pdf
       http://pdfserv.maxim-ic.com/en/ds/DS1994.pdf
       http://pdfserv.maxim-ic.com/en/ds/DS1427.pdf

AVAILABILITY

       http://www.owfs.org

AUTHOR

       Paul Alfille (paul.alfille@gmail.com)