DS2438(3) One-Wire File System DS2438(3) # [NAME](#NAME) **DS2438** - Smart Battery Monitor # [SYNOPSIS](#SYNOPSIS) ## [Temperature Voltages and Current.](#Temperature_Voltages_and_Current.) **26** \[.]XXXXXXXXXXXX\[XX]\[/\[ **CA** | **EE** | **date** | **disconnect/date** | **disconnect/udate** | **endcharge/date** | **endcharge/udate** | **IAD** | **offset** | **pages/page.\[0-7|ALL]** | **temperature** | **latesttemp** | **udate** | **VAD** | **VDD** | **vis** | See the file man3/standard\_mini.3so. ]] ## [Humidity sensor](#Humidity_sensor) **26** \[.]XXXXXXXXXXXX\[XX]\[/\[ **HIH4000/humidity** | **HIH5030/humidity** | **HTM1735/humidity** | **DATANAB/reset** | **DATANAB/humidity** | **humidity** | **temperature** ]] ## [Barometer](#Barometer) **26** \[.]XXXXXXXXXXXX\[XX]\[/\[ **B1-R1-A/pressure** | **B1-R1-A/gain** | **B1-R1-A/offset** | ]] ## [Light](#Light) **26** \[.]XXXXXXXXXXXX\[XX]\[/\[ **S3-R1-A/current** | **S3-R1-A/illuminance** | **S3-R1-A/gain** ]] # [FAMILY CODE](#FAMILY_CODE) *26* # [SPECIAL PROPERTIES](#SPECIAL_PROPERTIES) ## [pages/page.0 ... pages/page.7 pages/page.ALL](#pages/page.0_..._pages/page.7_pages/page.ALL) *read-write, binary* Memory is split into 8 pages of 8 bytes each. Only the pages 3-7 are really available, and some of that appears to be reserved. See the datasheet for details. *ALL* is an aggregate of the pages. Each page is accessed sequentially. ## [temperature](#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)**](/man/os/owfs/owfs.1) or [**owhttpd(1)**](/man/os/owfs/owhttpd.1) for choices. Default is Celsius. Conversion takes ~20 msec. ## [latesttemp](#latesttemp) *read-only, floating point* Latest measured temperature. Reading this node will never trigger a temperature conversion. Intended for use in conjunction with **/simultaneous/temperature.** ## [VAD VDD](#VAD_VDD) *read-only, floating point* Voltage read (~10 bits) at the one of the chip's two supply voltages. Range VDD= 2.4V to 10V, VAD=1.5 to 10V. ## [vis](#vis) *read-only, floating point* Current sensor reading, as a voltage difference. Value is in volts. Actual current depends on Rsens resistor (see datasheet). The formula for current is I = vis / Rsens with units in Amps and Ohms. Current measurement will be temporarily enabled (see *Ienable* ) if not currently enabled (pun intended) for this reading. # [CONFIGURATION PROPERTIES](#CONFIGURATION_PROPERTIES) ## [CA](#CA) *read-write, yes-no* *Current Accumulator Configuration* flag bit. If "on" (1) current is stored in page 7 bytes 4-7. If "off" (0) that page can be used for general storage. See the datasheet for more information. ## [EE](#EE) *read-write, yes-no* *Current Accumulator Shadow* flag bit. If "on" (1) current reading is stored to EEPROM. If "off" (0) that data will be lost when chip loses power. See the datasheet for more information ## [IAD](#IAD) *read-write, yes-no* *Current A/D Control* flag bit. If "on" (1) current measured at 36.41 Hz. If "off" (0) current measurements won't be made. See the datasheet for more information. # [DATE PROPERTIES](#DATE_PROPERTIES) ## [date](#date) *read-write, ascii* 26 character date representation of the *counter* value. Increments once per second. Setting *date* to a null string will put the current system time. Accepted date formats are: Sat\[urday] March 12 12:23:59 2001 Apr\[il] 4 9:34:56 2002 3/23/04 23:34:57 current locale setting (your system's format) ## [disconnect/date](#disconnect/date) *read-write, ascii* 26 character date representation of the *disconnect/udate* value. Time when the battery pack waws removed from the charger. Format is the same as the *date* property. ## [disconnect/udate](#disconnect/udate) *read-write, unsigned integer* Representation of *disconnect/date* as a number. See *udate* for details. ## [endcharge/date](#endcharge/date) *read-write, ascii* 26 character date representation of the *endcharge/udate* value. Format is the same as the *date* property. ## [endcharge/udate](#endcharge/udate) *read-write, unsigned integer* Representation of *endcharge/date* as a number. See *udate* for details. ## [udate](#udate) *read-write, unsigned integer* Time represented as a number. *udate* increments once per second. Usually set to unix time standard: number of seconds since Jan 1, 1970. The *date* field will be the unix representation (ascii text) of *udate* and setting either will change the other. # [HUMIDITY PROPERTIES](#HUMIDITY_PROPERTIES) ## [HIH4000/humidity](#HIH4000/humidity) *read-only, floating point* Relative humidity, as percent (1-100 scale). This value is for a design based on Honeywell's HIH-4000 humidity sensor. ## [HIH5030/humidity](#HIH5030/humidity) *read-only, floating point* Relative humidity, as percent (1-100 scale). This value is for a design based on Honeywell's HIH-5030/5031 humidity sensor. ## [HTM1735/humidity](#HTM1735/humidity) *read-only, floating point* Relative humidity, as percent (1-100 scale). This value is for a design based on Humirel's HTM-1735 humidity sensor. ## [DATANAB/humidity](#DATANAB/humidity) *read-only, floating point* Based on DataNAB's humidity sensor. It uses a HIH-4000 sensor and the current sensning rather than voltage readings from the DS2438. Calibration values are stored on chip, and a check field is stored in chip memory. ## [DATANAB/reset](#DATANAB/reset) *write-only, yes-no* Used to read calibration values and set the chip to current reading more. Should be automatically called when a humidity reading is requested. ## [humidity](#humidity) *read-only, floating point* Relative humidity, as percent (1-100 scale). The **DS2438** actually does not read humidity, but a widely available and publicised circuit based on the chip, does. This design is for the common Honeywell HIH-3610 humidity chip. The mostly compatible HIH-4000 chip uses different temperature compensation, so is better read from the *HIH4000/humidity* value. See the datasheets for details. If the chip is instead a DATANAB design, the *DATANAB/humidity* value will be automatically used. # [BAROMETER PROPERTIES](#BAROMETER_PROPERTIES) ## [B1-R1-A/pressure](#B1-R1-A/pressure) *read-only, floating point* Pressure reading, as milli-bars, or other unit depending on *settings/units/pressure\_scale*. This value is for the B1-R1-A barometer from Hobby-Boards, and assumes the standard calibration. ## [B1-R1-A/gain](#B1-R1-A/gain) *read/write, floating point* Calibration of pressure gain, as signed number, expressed as the same units as *B1-R1-A/pressure* per volt. This value will be multiplied with the measured voltage to get the *B1-R1-A/pressure* reading. It may have to be fine tuned for calibration purposes, although with the standard sensor, it will often be good enough to keep it as is. ## [B1-R1-A/offset](#B1-R1-A/offset) *read/write, floating point* Calibration of pressure offset, as signed number, same units as *B1-R1-A/pressure.* This value will be added to the *B1-R1-A/pressure* reading. The default value is 904.7 millibars, which may be altered to to compensate for elevation. # [SOLAR SENSOR PROPERTIES](#SOLAR_SENSOR_PROPERTIES) ## [S3-R1-A/current](#S3-R1-A/current) *read-only, floating point* Photo-diode current, in micro-amperes. This value is for the S3-R1-A solar radiation sensor from Hobby-Boards. Due to noise and offsets, this value may read as a negative number in low light conditions. The *offset* register can be modified to reduce the offset as much as possible. ## [S3-R1-A/illumination](#S3-R1-A/illumination) *read-only, floating point* Illumination, in lux. Always a positive number. This value is the lux reading from the solar sensor, taking *S3-R1-A/gain into consideration.* ## [S3-R1-A/gain](#S3-R1-A/gain) *read/write, floating point* Calibration of photo-diode gain expressed as lux per micro-amperes. The default value is for the SFH203P photo-diode from Osram, used bare. A different gain may be used for instance to compensate for an integrathing, white sphere placed over the diode. This value is for the S3-R1-A solar radiation sensor from Hobby-Boards, using the SFH203P photo-diode from Osram. # [MULTISENSOR PROPERTIES](#MULTISENSOR_PROPERTIES) ## [MultiSensor/type](#MultiSensor/type) *read-only, ascii* For *iButtonLink's MultiSensor* line of 1-wire devices, give the specific configuration based on a data byte set in memory. (Byte 0 of page 3). This can help interpretation of the sensor values, distinguishing, current from water from light. ## [offset](#offset) *read-write, integer* Correction for *current* readings. A value between -256 and 255. See the datasheet for details. Should be set to the negative of a true zero *current* reading. # [STANDARD PROPERTIES](#STANDARD_PROPERTIES) See the file man3/standard.3so. # [ALARMS](#ALARMS) None. # [DESCRIPTION](#DESCRIPTION) See the file man3/description.3so. ## [DS2438](#DS2438) The [**DS2438 (3)**](/man/os/owfs/DS2438.3) is a more complete form of the **DS2436** battery chip. Current sensing is available, but not implemented. The major advantage compared to the **DS2436** is that two voltages can be read, allowing one to correct circuit measurements for supply voltage and temperature. A better comparison is the **DS276x** family of chips. # [ADDRESSING](#ADDRESSING) See the file man3/addressing.3so. # [DATASHEET](#DATASHEET) http://pdfserv.maxim-ic.com/en/ds/DS2438.pdf http://pdfserv.maxim-ic.com/en/an/humsensor.pdf http://goo.gl/o9DH0 (Redirects to 009012\_2.pdf PDF file on honeywell.com website) http://www.phanderson.com/hih-4000.pdf http://www.humirel.com/product/fichier/HTM1735%20RevG%20.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) Egil Kvaleberg 2003 OWFS Manpage --- Document: DS2438(3) from owfs 3.2.4-r8 (Chainguard OS) Source: https://github.com/owfs/owfs