DS2755, DS2756 − Multichemistry Battery Fuel Gauge
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 |
]]
35 [.]XXXXXXXXXXXX[XX][/[ temperature | typeX/range_low | typeX/range_high | typeX/temperature
35
read-write,
integer
High and low alarm settings for temperature
read-write,
floating point
High and low alarm settings for volts
read-write,
yes-no
Lock any of the three eprom pages to prevent further writes.
Apparently setting lock is permanent.
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.
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.
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.
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.
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.
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
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.
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
read-write,
floating point
Integral of vis - vbias over time. Units are in
volthours
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.
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.
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.
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.
read-write,
yes-no
Default power-on state for the corresponding properties.
Temperature and voltage.
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.
http://pdfserv.maxim-ic.com/en/ds/DS2755.pdf
http://pdfserv.maxim-ic.com/en/ds/DS2756.pdf
http://www.owfs.org
Paul Alfille ([email protected])