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NAME

       DS2502 - Add-Only Memory (1 kBit)

       DS2502-E48, DS2502-UNW
              - 48-bit Node Address Chip, UniqueWare Add-Only Memory (1 kBit)

       DS1982, DS1982U
              - Add-Only iButton (1 kBit), UniqueWare iButton (1 kBit)

SYNOPSIS

       EPROM add-only memory.

       09  [.]XXXXXXXXXXXX[XX][/[ memory | pages/page.[0-3|ALL] | address | crc8 | id | locator |
       r_address | r_id | r_locator | type ]]

       89 [.]XXXXXXXXXXXX[XX][/[ mac_e | mac_fw |  memory  |  pages/page.[0-3|ALL]  |  project  |
       address | crc8 | id | locator | r_address | r_id | r_locator | type ]]

FAMILY CODE

       09     DS2502 DS1982

       89     DS2502-UNW DS2502-E48 DS1982U

SPECIAL PROPERTIES

   mac_e mac_fw
       read-only, binary
       64 bit or 80 bit media access control number. Unique, and unrelated to the 1-wire address.
       It is apparently used for ethernet or FireWire addressing, respectively.

   memory
       read-write, binary
       128 bytes of memory. Initially all bits are set to 1. Writing zero permanently alters  the
       memory.

   pages/page.0 ... pages/page.3 pages/page.ALL
       read-write, yes-no
       Memory  is  split  into  4 pages of 32 bytes each.  ALL is an aggregate of the pages. Each
       page is accessed sequentially.

   project
       read-only, binary
       32 bit project id.  Constant  0x0000  for  ethernet  and   0x00001128  for  firewire.  See
       Datasheets.

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.

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  fundamental  goal  has  been  ease  of  use,  flexibility  and
       correctness rather than speed.

   DS2502 DS1982
       The  DS2502  (3)  is  used  for write-once incremental storage. It's main advantage is for
       audit trails (i.e. a digital purse).

       The DS2502-E48 and DS2502-UNW are some of the UniqueWare class of  devices.  Some  of  the
       memory  was  preprogramed  at  the factory. See the datasheet for specifics.  The DS2502 ,
       DS2505 , and DS2506 differ in their  function  by  the  amount  of  on-board  memory  they
       possess.  (The internal protocols are slightly different, but the OWFS system handles this
       automatically.

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/DS2502.pdf
       http://pdfserv.maxim-ic.com/en/ds/DS2502-E48.pdf
       http://pdfserv.maxim-ic.com/en/ds/DS2502-UNW-DS2506S-UNW.pdf
       http://pdfserv.maxim-ic.com/en/ds/DS1982-F3-DS1982-F5.pdf
       http://pdfserv.maxim-ic.com/en/ds/DS1982U-DS1986U.pdf

SEE ALSO

   Programs
       owfs  (1)  owhttpd  (1) owftpd (1) owserver (1) owdir (1) owread (1) owwrite (1) owpresent
       (1) owtap (1)

   Configuration and testing
       owfs (5) owtap (1) owmon (1)

   Language bindings
       owtcl (3) owperl (3) owcapi (3)

   Clocks
       DS1427 (3) DS1904 (3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417 (3)

   ID
       DS2401 (3) DS2411 (3) DS1990A (3)

   Memory
       DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3) DS1995  (3)  DS1996  (3)
       DS2430A (3) DS2431 (3) DS2433 (3) DS2502 (3) DS2506 (3) DS28E04 (3) DS28EC20 (3)

   Switches
       DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3) InfernoEmbedded (3)

   Temperature
       DS1822  (3) DS1825 (3) DS1820 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921 (3) DS1821 (3)
       DS28EA00 (3) DS28E04 (3) EDS0064 (3) EDS0065 (3)  EDS0066  (3)  EDS0067  (3)  EDS0068  (3)
       EDS0071 (3) EDS0072 (3) MAX31826 (3)

   Humidity
       DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (3)

   Voltage
       DS2450 (3)

   Resistance
       DS2890 (3)

   Multifunction (current, voltage, temperature)
       DS2436  (3)  DS2437  (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3) DS2770 (3)
       DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)

   Counter
       DS2423 (3)

   LCD Screen
       LCD (3) DS2408 (3)

   Crypto
       DS1977 (3)

   Pressure
       DS2406 (3) TAI8570 (3) EDS0066 (3) EDS0068 (3)

   Moisture
       EEEF (3) DS2438 (3)

AVAILABILITY

       http://www.owfs.org

AUTHOR

       Paul Alfille (paul.alfille@gmail.com)