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DS1825(3)		     One-Wire File System		     DS1825(3)

NAME
       DS1825 -	Programmable Resolution	1-Wire Digital Thermometer with	ID

       MAX31826
	      -	Digital	Temperature Sensor with	1Kb Lockable EEPROM

       MAX31850	MAX31851
	      -	Cold-Junction Compensated Thermocouple

SYNOPSIS
   Thermometer with hardware address pins (DS1825)
       3B  [.]XXXXXXXXXXXX[XX][/[ fasttemp | temperature | temperature9	| tem-
       perature10 | temperature11 | temperature12 | power | prog_addr  |  tem-
       phigh  |	 templow  | address | crc8 | id	| locator | r_address |	r_id |
       r_locator | type	]]

   Digital Temperature Sensor with 1Kb Lockable	EEPROM (MAX31826)
       3B   [.]XXXXXXXXXXXX[XX][/[   temperature   |   power   |   memory    |
       pages/page.[0-15|ALL]  |	 prog_addr  |  address | crc8 |	id | locator |
       r_address | r_id	| r_locator | type ]]

   Cold-Junction Compensated Thermocouple (MAX31850 and	MAX31851)
       3B  [.]XXXXXXXXXXXX[XX][/[  temperature	|  thermocouple	 |   fault   |
       open_circuit | ground_short | vdd_short | power | prog_addr | address |
       crc8 | id | locator | r_address | r_id |	r_locator | type ]]

FAMILY CODE
       3B

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

   prog_addr
       read-only, 0-15
       A  distiguishing	 feature of the	DS1825 (3) is the ability to set hard-
       ware pins for an	address	(0-15).	This is	an alternative to  the	unique
       64-bit address that is set in the factory.

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

       For the MAX31850	MAX 31851 this is the cold-junction temperature	-- the
       temperature at the chip.	See thermocouple

   temperature9	temperature10 temperature11 temperature12
       read-only, floating point ( DS1825 only)

       Measured	temperature at 9 to 12 bit resolution. There is	a tradeoff  of
       time versus accuracy in the temperature measurement.

       The  MAX31826  MAX31850	MAX31851  measure  all	temperatures at	12 bit
       resoltion and will return that resolution to all	the possible  tempera-
       ture properties.

   fasttemp
       read-only, floating point
       Equivalent to temperature9

   thermocouple
       read-only, floating point ( MAX31850 MAX31851 only)

       Measured	 temperature  of  the  thermocouple at 16bit resolution. Cold-
       junction	temperature compensated.

       The actual thermocouple type used is set	by the selected	chip type, and
       is not discoverable in software.

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.

       The MAX31826 does  NOT  have  temperature  thresholds  and  temperature
       alarm.

MEMORY
       Only the	MAX31826 supports memory functions.

   pages/page.0	.. pages/page.15 pages/page.ALL
       read/write, binary
       EEPROM  memory  pages  of 8 bytes each. See the datasheet about locking
       contents.

   memory
       read/write, binary
       EEPROM memory of	128 bytes. See the datasheet about locking contents.

FAULT REPORTING
       Only the	MAX31850 MAX31851 supports fault reporting.

   fault
       read-only, yes-no
       Fault in	last thermocouple conversion

   open_circuit
       read-only, yes-no
       Thermocouple leads disconnected.

   ground_short
       read-only, yes-no
       Thermocouple lead shorted to ground.

   vdd_short
       read-only, yes-no
       Thermocouple lead shorted to supply voltage.

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	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  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 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 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 priciple	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 fundemental goal has been	ease of	use, flexibil-
       ity and correctness rather than speed.

   DS1825
       The DS1825 (3) is one of	several	available 1-wire temperature  sensors.
       Alternatives  are  the DS18S20 (3), DS18B20 (3),	and DS1822 (3) as well
       as temperature/voltage measurements in the DS2436 (3) and  DS2438  (3).
       For  truly  versatile  temperature measurements,	see the	protean	DS1921
       (3) Thermachron (3).

       The  DS1825  (3)	 can  select   between	 4   resolutionsspanning   the
       fastest/roughest	and slowest/best.

   MAX31826
       The  MAX31826  shares a family code with	the DS1825 but has differences
       in some of its functions.

       The MAX31826 has	128 btes of EEPROM memory (as 16  pages	 of  8	bytes)
       while the DS1825	has no memory available.

       The  MAX31826  measures temperature at 12 bit resolution	as fast	as the
       DS1825's	lowest resolution (and always uses 12-bit resolution). On  the
       other hand it has no temperature	thresholds or alarm function.

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.

       Both the	MAX31826 and the DS1825	allow hardware selection  of  part  of
       the  address,  which can	assist selecting between chips is some circuit
       designs.

DATASHEET
       DS1825 http://pdfserv.maxim-ic.com/en/ds/DS1825.pdf

       MAX31826
	      http://datasheets.maxim-ic.com/en/ds/MAX31826.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 EDS0066 (3) EDS0068 (3)

   Moisture
       EEEF (3)	DS2438 (3)

AVAILABILITY
       http://www.owfs.org

AUTHOR
       Paul Alfille (paul.alfille@gmail.com)

OWFS Manpage			     2006			     DS1825(3)

NAME | SYNOPSIS | FAMILY CODE | SPECIAL PROPERTIES | TEMPERATURE ALARM LIMITS | MEMORY | FAULT REPORTING | STANDARD PROPERTIES | DESCRIPTION | ADDRESSING | DATASHEET | SEE ALSO | AVAILABILITY | AUTHOR

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