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DS1904(3)

NAME

   DS2415,  DS1904,  DS2417  -  1-Wire  Time  Chip,  RTC (real time clock)
   iButton, 1-Wire Time Chip with Interrupt

SYNOPSIS

   Real time clock.
   24 [.]XXXXXXXXXXXX[XX][/[ date | flags | running | udate  |  address  |
   crc8 | id | locator | r_address | r_id | r_locator | type ]]

   Clock with interrupts
   27  [.]XXXXXXXXXXXX[XX][/[ date | enable | interval | itime | running |
   udate | address | crc8 | id | locator | r_address | r_id | r_locator  |
   type ]]

FAMILY CODE

   24     DS2415 DS1904

   27     DS2417

SPECIAL PROPERTIES

   date
   read-write, ascii
   26  character date representation of the counter value. Increments once
   per second while running
   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)

   enable
   read-write, yes-no
   State of the timer interrupt. 0=off 1=running.

   interval
   read-write, unsigned integer
   Interval  between  timer  interrupts.  Values:  0-7.  See  table  under
   DESCRIPTION  for  interpretation.   itime  will  reflect  the  interval
   chosen.

   itime
   read-write, unsigned integer
   Interval between timer interrupts. Value in seconds.  See  table  under
   DESCRIPTION  for  interpretation  and acceptable values.  interval will
   reflect the itime chosen.

   flags
   read-write, unsigned integer
   General use data. 4 bits (0-15 accepted values).

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

   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.

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.

   DS2415 DS1904
   The DS2415 (3) and DS1904 (3) are simple clocks that can be read on the
   1-wire bus. They can also  be  used  the  time  an  event,  for  remote
   confirmation.

   DS2417
   The   DS2417   has  the  same  clock  function,  but  also  includes  a
   programmable interval interrupt. Values Allowed are:
   0 1sec
   1 4sec
   2 32s = .5m
   3 6 = 1m
   4 2048s = .5h
   5 4096s = 1h
   6 65536s = 18h
   7 131072s = 36h

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/DS2415.pdf
   http://pdfserv.maxim-ic.com/en/ds/DS1904.pdf
   http://pdfserv.maxim-ic.com/en/ds/DS2417.pdf

AVAILABILITY

   http://www.owfs.org

AUTHOR

   Paul Alfille (paul.alfille@gmail.com)

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