DS2751(3) One-Wire File System DS2751(3) NAME DS2751 - Multichemistry Battery Fuel Gauge 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 FAMILY CODE 51 SPECIAL PROPERTIES amphours read-write, floating point Accumulated amperage read by current sensor. Units are in Amp-hr (Assumes internal 25mOhm resistor). Derived from volthours / Rinternal. Formally amphours is the integral of current - currentbias over time. current read-only, floating point Current reading. Units are in Amp (Assumes internal 25 mOhm resistor). De- rived from vis / Rinternal. currentbias read-write, floating point Fixed offset applied to each current measurement. 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 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 implementa- tion 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 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. temperature read-only, floating point Temperature read by the chip at high resolution (~13 bits). Units are se- lected 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 prop- erty. The current reading is derived from vis assuming the internal 25 mOhm re- sistor 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 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 de- pends 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 temper- ature 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 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 corre- sponds to a 1 bit value. defaultpmod read-write, yes-no Default power-on state for the corresponding properties. 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 ap- plications 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 asso- ciated 1-wire physical connections with a unique 1-wire code. If the con- nection is behind a Link Locator the locator will show a unique 8-byte num- ber (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? type read-only, ascii Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging (iButton vs chip) will not be distiguished. ALARMS None. 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-connec- tor 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, temper- ature, 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 indi- vidually 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 con- sistent interface. The goal is to provide an easy set of tools for a soft- ware 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 correct- ness 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. ADDRESSING All 1-wire devices are factory assigned a unique 64-bit address. This ad- dress 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. DATASHEET http://pdfserv.maxim-ic.com/en/ds/DS2751.pdf 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) Infer- noEmbedded (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) AVAILABILITY http://www.owfs.org AUTHOR Paul Alfille (paul.alfille@gmail.com) OWFS Manpage 2003 DS2751(3)
NAME | SYNOPSIS | FAMILY CODE | SPECIAL PROPERTIES | THERMOCOUPLE | OBSCURE PROPERTIES | STANDARD PROPERTIES | ALARMS | DESCRIPTION | ADDRESSING | DATASHEET | SEE ALSO | AVAILABILITY | AUTHOR
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