DS2751(3)

🌸 NAME 🌸

DS2751 — Multichemistry Battery Fuel Gauge. (Yes bestie, this is a DS2751(3) page from the One-Wire File System, aka OWFS. Buckle up. 💖)

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🎀 SYNOPSIS 🎀

Temperature Voltage, Current, Memory, and Switch.

51 [.]XXXXXXXXXXXX[XX][/[ amphours | current | currentbias |
lock.[0-1|ALL] | memory | pages/page.[0-1|ALL] | PIO | sensed |
temperature | typeX/range_low | typeX/range_high | typeX/temperature |
vbias | vis | volt | volthours |
defaultpmod | pmod | por | uven |
address | crc8 | id | locator | r_address | r_id | r_locator | type ]]

Thermocouple

51 [.]XXXXXXXXXXXX[XX][/[ temperature | typeX/range_low |
typeX/range_high | typeX/temperature

(fr fr that's exactly how it ends — no closing bracket, the original said so, and I am NOT about to editorialize 💀)

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✨ FAMILY CODE ✨

51

Like, the family code. The whole vibe of the device. 51. Periodt.

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🦋 SPECIAL PROPERTIES 🦋

amphours

read-write, floating point.

The accumulated amperage that got read by the current sensor. Units are in Amp-hr (and yes, this assumes the internal 25mOhm resistor, ok). Derived from volthours / Rinternal. Formally, amphours is the integral of current − currentbias over time. It's giving calculus, honestly. 😭

current

read-only, floating point.

The current reading. Units are in Amp (assumes internal 25 mOhm resistor). Derived from vis / Rinternal. Slay.

currentbias

read-write, floating point.

A fixed offset that gets applied to each current measurement. It's used in the amphours value. Assumes internal 25mOhm resistor. Units are Amp and range from -.08A to .08A. Derived from vbias / Rinternal.

lock.[0-1|ALL]

read-write, yes-no.

Locks either one of the two eprom pages so nobody can write to them anymore. And apparently setting lock is permanent. 👑 No take-backs. None. Zero. Be so careful, bestie.

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/page.[0-1|ALL]

read-write, binary.

Two 16 byte areas of memory for your 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, which lets you do 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. Only useful 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 — it never stops, it's an icon.

vbias

read-write, floating point.

A 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.

The current sensor reading (unknown external resistor). It measures the voltage gradient between the Vis pins. Units are in Volts.

The vis readings get 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. 🙈

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. Math girlie behavior, we love her. 💅

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🧚 THERMOCOUPLE 🧚

typeX/

directory.

Thermocouple circuit using the DS2760 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, floating 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. Two different temps, two different vibes. 🔥

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🔮 OBSCURE PROPERTIES 🔮

pmod por uven

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.

defaultpmod

read-write, yes-no.

Default power-on state for the corresponding properties.

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⭐ STANDARD PROPERTIES ⭐

address / r_address

read-only, ascii.

The entire 64-bit unique ID. Given as upper case hexadecimal 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. Computed from the preceding 56 bits of the unique ID number. Given as upper case hexadecimal digits (0-9A-F).

family

read-only, ascii.

The 8-bit family code. Unique to each type of device. Given as upper case hexadecimal 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 hexadecimal digits (0-9A-F).

r_id is the id in reverse order, which is often used in other applications 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 hexadecimal) 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?

DEPRECATED, bestie. It's giving legacy. Still listed, still documented, but don't build your whole personality on it.

type

read-only, ascii.

Part name assigned by Dallas Semi. E.g. DS2401. Alternative packaging (iButton vs chip) will not be distiguished.

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🚨 ALARMS 🚨

None.

(An empty alarms section is honestly such a calm, unbothered energy. ✨)

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📖 DESCRIPTION 📖

1-Wire

1-wire is a wiring protocol and series of devices designed and manufactured 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 (humidity, 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 encryption 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, parallel, 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 principle is to create a virtual filesystem, with the unique ID being the directory, and the individual 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 communication. Still the fundamental goal has been ease of use, flexibility and correctness rather than speed.

DS2751

The DS2751(3) is battery charging controllers similar to the DS2760(3).

A number of interesting devices can be built with the DS2751(3) including thermocouples. Support for thermocouples in built into the software, using the embedded thermister as the cold junction temperature.

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🧭 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 hexadecimal, 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. No pressure, but like, it must be correct. 😌

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📄 DATASHEET 📄

http://pdfserv.maxim-ic.com/en/ds/DS2751.pdf

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👀 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) InfernoEmbedded(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(3) EDS0066(3) EDS0068(3)

Moisture

EEEF(3) DS2438(3)

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🌈 AVAILABILITY 🌈

http://www.owfs.org

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🫶 AUTHOR 🫶

Paul Alfille (paul.alfille@gmail.com)

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And that's the whole page, bestie. This one is from the OWFS Manpage — the source/version line says OWFS Manpage, dated 2003, and the page itself is DS2751(3). Go forth and read your battery fuel gauge, you absolute main character. 💖✨🎀