NAME¶
DS2755, DS2756 - Multichemistry Battery Fuel Gauge
SYNOPSIS¶
Temperature Voltage, Current, Memory, and Switch.¶
35 [.]XXXXXXXXXXXX[XX][/[
alarm_set/[volthigh|voltlow|temphigh|templow] |
lock.[0-2|ALL] |
memory |
pages/page.[0-2|ALL] |
PIO |
sensed |
temperature |
vbias |
vis |
volt |
volthours |
defaultpmod |
pie0 |
pie1 |
rnaop |
ios |
uben |
ovd |
pmod |
por |
uven |
address |
crc8 |
id |
locator |
r_address |
r_id |
r_locator |
type ]]
Thermocouple¶
35 [.]XXXXXXXXXXXX[XX][/[
temperature |
typeX/range_low |
typeX/range_high |
typeX/temperature
FAMILY CODE¶
35
SPECIAL PROPERTIES¶
alarm_set/templow alarm_set/temphigh¶
read-write, integer
High and low alarm settings for
temperature
alarm_set/voltlow alarm_set/volthigh¶
read-write, floating point
High and low alarm settings for
volts
lock.[0-2|ALL]¶
read-write, yes-no
Lock any of the three 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.[0-2|ALL]¶
read-write, binary Three 32 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
implementation 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
selected 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
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
THERMOCOUPLE¶
typeX/¶
directory
Thermocouple circuit using the
DS2755 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, 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
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.
OBSCURE PROPERTIES¶
pmod por uven pie0 pie1 ios uben ovd rnaop¶
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.
STANDARD PROPERTIES¶
address¶
r_address¶
read-only, ascii
The entire 64-bit unique ID. Given as upper case hexidecimal 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 hexidecimal
digits (0-9A-F).
family¶
read-only, ascii
The 8-bit family code. Unique to each
type of device. Given as upper case
hexidecimal digits (0-9A-F).
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 hexidecimal 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 hexidecimal) 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¶
Temperature and voltage.
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 priciple 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 fundemental
goal has been ease of use, flexibility and correctness rather than speed.
DS2755 DS2756¶
The
DS2755 (3) and
DS2756 (3) are battery charging controllers
similar to the
DS2751 (3) except no internal resistor option and a
larger EEPROM memory.
The
DS2756 (3) adds suspend modes (
pie0 pie1 ) to the
DS2755
(3)
A number of interesting devices can be built with the
DS2755 (3) and
DS2756 (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 address is
of the form:
- Family Code
- 8 bits
- Address
- 48 bits
- CRC
- 8 bits
Addressing under OWFS is in hexidecimal, 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/DS2755.pdf
http://pdfserv.maxim-ic.com/en/ds/DS2756.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)
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)
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)
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 EDS0066 (3) EDS0068 (3)
AVAILABILITY¶
http://www.owfs.org
AUTHOR¶
Paul Alfille (paul.alfille@gmail.com)