Copyright (c) 2003-2004 Paul H Alfille, MD
(paul.alfille@gmail.com)
Device manual page for the OWFS -- 1-wire filesystem package
Based on Dallas Semiconductor, Inc's datasheets, and trial and error.
Free for all use. No warranty. None. Use at your own risk.
DS2788 - Stand-alone Fuel Gauge with LED Drivers
32 [.]XXXXXXXXXXXX[XX][/[ lock.[0-1|ALL] | memory | pages/page.[0-1|ALL] | PIO | sensed | temperature | vbias | vis | volt | volthours |
aef | chgtf | ds | learnf | pmod | porf | rnaop | sef | uven | uvf |
.so man3/standard_mini.3so ]]
32 [.]XXXXXXXXXXXX[XX][/[ temperature | typeX/range_low | typeX/range_high | typeX/temperature
32
Lock either of the two eprom pages to prevent further writes. Apparently setting lock is permanent.
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 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 implementation in that all of memory is not accessible.
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 DS2680 See the datasheet for details.
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 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.
Fixed offset applied to each vis measurement. Used for the volthours value. Units are in Volts.
Range -2.0mV to 2.0mV
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.
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
Integral of vis - vbias over time. Units are in volthours
Thermocouple circuit using the DS2780 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 pointThe lower and upper temperature supported by this thermocouple (at least by the conversion routines). In the globally chosen temperature units.
read-only, floating pointThermocouple 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.
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.
A number of interesting devices can be built with the DS2780 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/DS2780.pdf
http://pdfserv.maxim-ic.com/en/ds/DS2788.pdf