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NAME

       DS28EA00 - 1-Wire Digital Thermometer with Sequence Detect and PIO

SYNOPSIS

       Thermometer, PIO and Chain.

       42  [.]XXXXXXXXXXXX[XX][/[  fasttemp  |  temperature  |  temperature9  |  temperature10  |
       temperature11 | temperature12 die | power  |  temphigh  |  templow  |  PIO.A|B|ALL.BYTE  |
       latch.A|B|ALL.BYTE | sensed.A|B|ALL.BYTE

       address | crc8 | id | locator | r_address | r_id | r_locator | type ]]

FAMILY CODE

       42

SPECIAL PROPERTIES

   power
       read-only,yes-no
       Is the chip powered externally (=1) or from the parasitically from the data bus (=0)?

TEMPERATURE PROPERTIES

   temperature
       read-only, floating point
       Measured temperature with 12 bit resolution.

   temperature9 temperature10 temperature11 temperature12
       read-only,  floating  point  Measured  temperature  at  9 to 12 bit resolution. There is a
       tradeoff of time versus accuracy in the temperature measurement.

   fasttemp
       read-only, floating point
       Equivalent to temperature9

PIO PROPERTIES

   PIO.A|B|ALL|BYTE
       read-write, yes-no
       Two  channels  of  sensors/switches.  We  use   the   logical   raqther   than   eletrical
       interpretation: 0=off (non-conducting) 1=on (conducting -- to ground)

       The PIO channels are alternatively used for the sequence-detect (chain) mode.

       Reading sensed gives the inverse value of the cooresponding PIO.

       Reading PIO gives the actual pin values. Use the latch property to see how the pin is set.

   latch.A|B|ALL|BYTE
       read-only, yes-no
       Set (intended) va;ue of the PIO pins.

   sensed.A|B|ALL|BYTE
       read-only, yes-no
       Actual logical level at the PIO pins.

SPECIAL PROPERTIES

   power
       read-only,yes-no
       Is the chip powered externally (=1) or from the parasitically from the data bus (=0)?

TEMPERATURE ALARM LIMITS

       When  the device exceeds either temphigh or templow temperature threshold the device is in
       the alarm state, and will appear in the alarm directory. This provides an easy way to poll
       for  temperatures  that  are  unsafe, especially if simultaneous temperature conversion is
       done.

       Units for the temperature alarms are in the  same  temperature  scale  that  was  set  for
       temperature measurements.

       Temperature  thresholds  are stored in non-volatile memory and persist until changed, even
       if power is lost.

   temphigh
       read-write, integer
       Shows or sets the lower limit for the high temperature alarm state.

   templow
       read-write, integer
       Shows or sets the upper limit for the low temperature alarm state.

STANDARD PROPERTIES

   address
   r_address
       read-only, ascii
       The entire 64-bit unique ID. Given as upper case hexidecimal 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 hexidecimal  digits  (0-9A-
       F).

   family
       read-only, ascii
       The  8-bit  family  code.  Unique  to each type of device. Given as upper case hexidecimal
       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 hexidecimal 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 hexidecimal) 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.

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 priciple 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.

   DS28EA00
       The DS28EA00 (3) is one of  several  available  1-wire  temperature  sensors.  It  is  the
       replacement for the DS18S20 (3) Alternatives are DS1822 (3) as well as temperature/vlotage
       measurements  in  the  DS2436  (3)  and  DS2438  (3).   For  truly  versatile  temperature
       measurements, see the protean DS1921 (3) Thermachron (3).
       The DS28EA00 has special switch/sequence detect properties. In sequence mode, the PIO pins
       are daisy-chained to the next DS28EA00, allowing the system to step through  the  physical
       sequence of the DS28EA00s.

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 hexidecimal, 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/DS28EA00.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)

   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)

   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 EDS0066 (3) EDS0068 (3)

AVAILABILITY

       http://www.owfs.org

AUTHOR

       Paul Alfille (paul.alfille@gmail.com)