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DS2760(3)		     One-Wire File System		     DS2760(3)

NAME
       DS2781 -	Stand-alone Fuel Gauge IC

SYNOPSIS
   Temperature Voltage Current Memory and Switch.
       3D     [.]XXXXXXXXXXXX[XX][/[	 lock.[0-1|ALL]	    |	  memory     |
       pages/page.[0-1|ALL] | PIO | sensed |  temperature  |  vbias  |	vis  |
       vis_avg | vis_offset | volt | volthours |
       aef | chgtf | learnf | pmod | porf | sef	| uven | uvf |
       address | crc8 |	id | locator | r_address | r_id	| r_locator | type ]]

   Thermocouple
       3D    [.]XXXXXXXXXXXX[XX][/[    temperature    |	   typeX/range_low   |
       typeX/range_high	| typeX/temperature

FAMILY CODE
       3D

SPECIAL	PROPERTIES
   lock.[0-1|ALL]
       read-write, yes-no
       Lock either of the two eprom pages to prevent  further  writes.	Appar-
       ently setting lock is permanent.

   memory
       read-write, binary
       Access  to  the	full  256 byte memory range. Much of this space	is re-
       served or special use. User space is the	page area.
       See the DATASHEET for a full memory map.

   pages/pages.[0-1|ALL]
       read-write, binary Two 16 byte areas of memory  for  user  application.
       The lock	property can prevent further alteration.
       NOTE that the page property is different	from the common	OWFS implemen-
       tation in that all of memory is not accessible.

   PIO
       write-only, yes-no
       Controls	the PIO	pin allowing external switching.
       Writing "1" turns the PIO pin on	(conducting). Writing  "0"  makes  the
       pin  non-conducting.  The logical state of the voltage can be read with
       the sensed property. This will reflect the current voltage at the  pin,
       not the value sent to PIO
       Note  also  that	 PIO  will  also be altered by the power-status	of the
       DS2680 See the datasheet	for details.

   sensed
       read-only, yes-no
       The logical voltage at the PIO pin. Useful only if the PIO property  is
       set to "0" (non-conducting).
       Value will be 0 or 1 depending on the voltage threshold.

   temperature
       read-only, floating point
       Temperature  read  by the chip at high resolution (~13 bits). Units are
       selected	from the invoking command line.	See owfs(1) or owhttpd(1)  for
       choices.	Default	is Celsius.
       Conversion is continuous.

   vbias
       read-write, floating point
       Fixed  offset  applied  to each vis measurement.	Used for the volthours
       value. Units are	in Volts.
       Range -2.0mV to 2.0mV

   vis
       read-only, floating point
       Current sensor reading (unknown external	resistor). Measures the	 volt-
       age gradient between the	Vis pins. Units	are in Volts
       The  vis	 readings  are	integrated  over time to provide the volthours
       property.
       The current reading is derived from vis assuming	the internal  25  mOhm
       resistor	is employed. There is no way to	know this through software.

   vis_avg
       read-only, floating point
       Average	current	 sensor	 reading (unknown external resistor). Measures
       the voltage gradient between the	Vis pins. Units	are in Volts

   vis_offset
       read-write, floating point
       Offset to vis for current sensor	reading	(unknown  external  resistor).
       Units are in Volts

   volt
       read-only, floating point
       Voltage	read  at  the  voltage	sensor;. This is separate from the vis
       voltage that is used for	current	measurement. Units are Volts
       Range is	between	0 and 4.75V

   volthours
       read-write, floating point
       Integral	of vis - vbias over time. Units	are in volthours

THERMOCOUPLE
   typeX/
       directory
       Thermocouple circuit using the DS2781 to	read the Seebeck  voltage  and
       the  reference temperature. Since the type interpretation of the	values
       read depends on the type	of thermocouple, the correct directory must be
       chosen.	Supported thermocouple types include types B, E, J, K, N, R, S
       and T.

   typeX/range_low typeX/ranges_high
       read-only, flaoting point
       The lower and upper temperature	supported  by  this  thermocouple  (at
       least  by  the conversion routines). In the globally chosen temperature
       units.

   typeX/temperature
       read-only, floating point
       Thermocouple temperature. Requires a voltage  and  temperature  conver-
       sion. Returned in globally chosen temperature units.
       Note:  there  are  two  types of	temperature measurements possible. The
       temperature value in the	main device directory is the reference temper-
       ature  read  at the chip. The typeX/temperature value is	at the thermo-
       couple junction,	probably remote	from the chip.

OBSCURE	PROPERTIES
   aef chgtf learnf pmod porf sef uven uvf
       varies, yes-no
       Bit flags corresponding to various battery management functions of  the
       chip. See the DATASHEET for details of the identically named entries.
       In general, writing "0" corresponds to a	0 bit value, and non-zero cor-
       responds	to a 1 bit 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	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.

ALARMS
       None.

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.

   DS2781
       The DS2781 (3) is a battery charging controller.	It has elaborate algo-
       rithms for estimating battery capacity.

       A  number of interesting	devices	can be built with the DS2781 including
       thermocouples. Support for thermocouples	in built  into	the  software,
       using the embedded thermister as	the cold junction temperature.

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/DS2781.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			     2003			     DS2760(3)

NAME | SYNOPSIS | FAMILY CODE | SPECIAL PROPERTIES | THERMOCOUPLE | OBSCURE PROPERTIES | STANDARD PROPERTIES | ALARMS | DESCRIPTION | ADDRESSING | DATASHEET | SEE ALSO | AVAILABILITY | AUTHOR

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