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DS2740(3)		     One-Wire File System		     DS2740(3)

NAME
       DS2740 -	High-Precision Coulomb Counter

SYNOPSIS
       Voltage and Switch

       36  [.]XXXXXXXXXXXX[XX][/[  memory  |  PIO  |  sensed  |	 vis | vis_B |
       volthours |
       smod |
       address | crc8 |	id | locator | r_address | r_id	| r_locator | type ]]

FAMILY CODE
       36

SPECIAL	PROPERTIES
   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.

   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
       DS2670 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.

   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_B
       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 vis_B is from a different tuning of the DS2740 (3) chip with	faster
       sampling	and lower resolution.  There is	no way to  know	 this  through
       software.

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

OBSCURE	PROPERTIES
   smod
       read-write, 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.
       Default power-on	state for the corresponding properties.

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.

   DS2740
       The  DS2740  (3)	 is a class of battery charging	controllers. This chip
       measures	voltage	and volthours, and has a pin that can be used for con-
       trol.

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/DS2740.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			     DS2740(3)

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

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