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

# [NAME](#NAME)

**DS2740** - High-Precision Coulomb Counter

# [SYNOPSIS](#SYNOPSIS)

Voltage and Switch

**36** \[.]XXXXXXXXXXXX\[XX][/[ **memory** | **PIO** | **sensed** | **vis** | **vis\_B** | **volthours** |  
**smod** |

See the file man3/standard\_mini.3so.

]]

# [FAMILY CODE](#FAMILY_CODE)

*36*

# [SPECIAL PROPERTIES](#SPECIAL_PROPERTIES)

## [memory](#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](#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](#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](#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](#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)*](/man/os/owfs/DS2740.3) chip with faster sampling and lower resolution. There is no way to know this through software.

## [volthours](#volthours)

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

# [OBSCURE PROPERTIES](#OBSCURE_PROPERTIES)

## [smod](#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](#STANDARD_PROPERTIES)

See the file man3/standard.3so.

# [ALARMS](#ALARMS)

None.

# [DESCRIPTION](#DESCRIPTION)

See the file man3/description.3so.

## [DS2740](#DS2740)

The [**DS2740 (3)**](/man/os/owfs/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](#ADDRESSING)

See the file man3/addressing.3so.

# [DATASHEET](#DATASHEET)

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

# [SEE ALSO](#SEE_ALSO)

See the file man3/seealso.3so.

# [AVAILABILITY](#AVAILABILITY)

http://www.owfs.org

# [AUTHOR](#AUTHOR)

Paul Alfille (paul.alfille@gmail.com)

2003 OWFS Manpage

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Document: DS2740(3) from owfs 3.2.4-r9 (Chainguard OS)
Source: https://github.com/owfs/owfs