DragonFly On-Line Manual Pages

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 |

       See the file man3/standard_mini.3so.

       ]]

   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.
       Apparently setting lock is permanent.

   memory
       read-write, binary
       Access to the full 256 byte memory range. Much of this space is
       reserved 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
       implementation 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
       voltage 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
       conversion. 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
       temperature read at the chip. The typeX/temperature value is at the
       thermocouple 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
       corresponds to a 1 bit value.

STANDARD PROPERTIES
       See the file man3/standard.3so.

ALARMS
       None.

DESCRIPTION
       See the file man3/description.3so.

   DS2781
       The DS2781 (3) is a battery charging controller. It has elaborate
       algorithms 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
       See the file man3/addressing.3so.

DATASHEET
       http://pdfserv.maxim-ic.com/en/ds/DS2781.pdf

SEE ALSO
       See the file man3/seealso.3so.

AVAILABILITY
       http://www.owfs.org

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

OWFS Manpage                         2003                            DS2760(3)