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DS28EA00(3)		     One-Wire File System		   DS28EA00(3)

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

SYNOPSIS
       Thermometer, PIO	and Chain.

       42  [.]XXXXXXXXXXXX[XX][/[ fasttemp | temperature | temperature9	| tem-
       perature10 | temperature11 | temperature12 | latesttemp | die | power |
       temphigh	 | templow | tempres | 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.

   latesttemp
       read-only, floating point
       Measured	temperature at 9 to 12 bit resolution, depending on the	 reso-
       lution  of  the	latest conversion on this chip.	Reading	this node will
       never trigger a temperature conversion. Intended	for use	in conjunction
       with /simultaneous/temperature.

   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 elet-
       rical 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  thresh-
       old  the	device is in the alarm state, and will appear in the alarm di-
       rectory.	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.

TEMPERATURE RESOLUTION DEFAULT VALUE
   tempres
       read-write, integer
       The  device employs a non-volatile memory to store the default tempera-
       ture resolution (9, 10, 11 or 12	bits) to be  applied  after  power-up.
       This is useful if you use simultaneous temperature conversions. Reading
       this node gives you the value stored in the non-volatile	memory.	 Writ-
       ing sets	a new power-on resolution value.

       As  a  side effect, reading this	node resets the	temperature resolution
       used by simultaneous temperature	conversions to its power-on value.  It
       also affects the	resolution value used by latesttemp, to	scale the lat-
       est conversion value, so	make sure to re-sample the temperature	before
       accessing latesttemp after writing or reading the tempres value.

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. Com-
       puted from the preceding	56 bits	of the unique ID number. Given as  up-
       per 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 applica-
       tions 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.

DESCRIPTION
   1-Wire
       1-wire is a wiring protocol and series of devices designed and manufac-
       tured 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  (humid-
       ity, 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 en-
       cryption	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,  par-
       allel, 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 in-
       dividual	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 com-
       munication. Still the fundamental goal has been ease of use,  flexibil-
       ity and correctness rather than speed.

   DS28EA00
       The  DS28EA00  (3)  is one of several available 1-wire temperature sen-
       sors. 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 pro-
       tean 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 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/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)  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)

OWFS Manpage			     2003			   DS28EA00(3)

NAME | SYNOPSIS | FAMILY CODE | SPECIAL PROPERTIES | TEMPERATURE PROPERTIES | PIO PROPERTIES | SPECIAL PROPERTIES | TEMPERATURE ALARM LIMITS | TEMPERATURE RESOLUTION DEFAULT VALUE | STANDARD PROPERTIES | DESCRIPTION | ADDRESSING | DATASHEET | SEE ALSO | AVAILABILITY | AUTHOR

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