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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 |

       See the file man3/standard_mini.3so.

       ]]


FAMILY CODE

       36


SPECIAL PROPERTIES

   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.

   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
       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_B
       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 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
       corresponds to a 1 bit value.
       Default power-on state for the corresponding properties.


STANDARD PROPERTIES

       See the file man3/standard.3so.


ALARMS

       None.


DESCRIPTION

       See the file man3/description.3so.

   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
       control.


ADDRESSING

       See the file man3/addressing.3so.


DATASHEET

       http://pdfserv.maxim-ic.com/en/ds/DS2740.pdf


SEE ALSO

       See the file man3/seealso.3so.


AVAILABILITY

       http://www.owfs.org


AUTHOR

       Paul Alfille (paul.alfille@gmail.com)

OWFS Manpage                         2003                            DS2740(3)

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