DS2788(3)

1DS2760(3)                    One-Wire File System                    DS2760(3)
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3
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NAME

6       DS2780 - Stand-alone Fuel Gauge IC
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8       DS2788 - Stand-alone Fuel Gauge with LED Drivers
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SYNOPSIS

11   Temperature Voltage Current Memory and Switch.
12       32     [.]XXXXXXXXXXXX[XX][/[     lock.[0-1|ALL]     |     memory     |
13       pages/page.[0-1|ALL] | PIO | sensed | temperature | vbias | vis |  volt
14       | volthours |
15       aef | chgtf | ds | learnf | pmod | porf | rnaop | sef | uven | uvf |
16       address | crc8 | id | locator | r_address | r_id | r_locator | type ]]
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18   Thermocouple
19       32    [.]XXXXXXXXXXXX[XX][/[    temperature    |    typeX/range_low   |
20       typeX/range_high | typeX/temperature
21

FAMILY CODE

23       32
24

SPECIAL PROPERTIES

26   lock.[0-1|ALL]
27       read-write, yes-no
28       Lock either of the two eprom pages to prevent  further  writes.  Appar‐
29       ently setting lock is permanent.
30
31   memory
32       read-write, binary
33       Access  to  the  full  256 byte memory range. Much of this space is re‐
34       served or special use. User space is the page area.
35       See the DATASHEET for a full memory map.
36
37   pages/pages.[0-1|ALL]
38       read-write, binary Two 16 byte areas of memory  for  user  application.
39       The lock property can prevent further alteration.
40       NOTE that the page property is different from the common OWFS implemen‐
41       tation in that all of memory is not accessible.
42
43   PIO
44       write-only, yes-no
45       Controls the PIO pin allowing external switching.
46       Writing "1" turns the PIO pin on (conducting). Writing  "0"  makes  the
47       pin  non-conducting.  The logical state of the voltage can be read with
48       the sensed property. This will reflect the current voltage at the  pin,
49       not the value sent to PIO
50       Note  also  that  PIO  will  also be altered by the power-status of the
51       DS2680 See the datasheet for details.
52
53   sensed
54       read-only, yes-no
55       The logical voltage at the PIO pin. Useful only if the PIO property  is
56       set to "0" (non-conducting).
57       Value will be 0 or 1 depending on the voltage threshold.
58
59   temperature
60       read-only, floating point
61       Temperature  read  by the chip at high resolution (~13 bits). Units are
62       selected from the invoking command line. See owfs(1) or owhttpd(1)  for
63       choices. Default is Celsius.
64       Conversion is continuous.
65
66   vbias
67       read-write, floating point
68       Fixed  offset  applied  to each vis measurement. Used for the volthours
69       value. Units are in Volts.
70       Range -2.0mV to 2.0mV
71
72   vis
73       read-only, floating point
74       Current sensor reading (unknown external resistor). Measures the  volt‐
75       age gradient between the Vis pins. Units are in Volts
76       The  vis  readings  are  integrated  over time to provide the volthours
77       property.
78       The current reading is derived from vis assuming the internal  25  mOhm
79       resistor is employed. There is no way to know this through software.
80
81   volt
82       read-only, floating point
83       Voltage  read  at  the  voltage  sensor;. This is separate from the vis
84       voltage that is used for current measurement. Units are Volts
85       Range is between 0 and 4.75V
86
87   volthours
88       read-write, floating point
89       Integral of vis - vbias over time. Units are in volthours
90

THERMOCOUPLE

92   typeX/
93       directory
94       Thermocouple circuit using the DS2780 to read the Seebeck  voltage  and
95       the  reference temperature. Since the type interpretation of the values
96       read depends on the type of thermocouple, the correct directory must be
97       chosen.  Supported thermocouple types include types B, E, J, K, N, R, S
98       and T.
99
100   typeX/range_low typeX/ranges_high
101       read-only, flaoting point
102       The lower and upper temperature  supported  by  this  thermocouple  (at
103       least  by  the conversion routines). In the globally chosen temperature
104       units.
105
106   typeX/temperature
107       read-only, floating point
108       Thermocouple temperature. Requires a voltage  and  temperature  conver‐
109       sion. Returned in globally chosen temperature units.
110       Note:  there  are  two  types of temperature measurements possible. The
111       temperature value in the main device directory is the reference temper‐
112       ature  read  at the chip. The typeX/temperature value is at the thermo‐
113       couple junction, probably remote from the chip.
114

OBSCURE PROPERTIES

116   aef chgtf dc learnf pmod porf rnaop sef uven uvf
117       varies, yes-no
118       Bit flags corresponding to various battery management functions of  the
119       chip. See the DATASHEET for details of the identically named entries.
120       In general, writing "0" corresponds to a 0 bit value, and non-zero cor‐
121       responds to a 1 bit value.
122

STANDARD PROPERTIES

124   address
125   r_address
126       read-only, ascii
127       The entire 64-bit unique ID. Given as  upper  case  hexadecimal  digits
128       (0-9A-F).
129       address starts with the family code
130       r address is the address in reverse order, which is often used in other
131       applications and labeling.
132
133   crc8
134       read-only, ascii
135       The 8-bit error correction portion. Uses cyclic redundancy check.  Com‐
136       puted  from the preceding 56 bits of the unique ID number. Given as up‐
137       per case hexadecimal digits (0-9A-F).
138
139   family
140       read-only, ascii
141       The 8-bit family code. Unique to each type of device.  Given  as  upper
142       case hexadecimal digits (0-9A-F).
143
144   id
145   r_id
146       read-only, ascii
147       The 48-bit middle portion of the unique ID number. Does not include the
148       family code or CRC. Given as upper case hexadecimal digits (0-9A-F).
149       r id is the id in reverse order, which is often used in other  applica‐
150       tions and labeling.
151
152   locator
153   r_locator
154       read-only, ascii
155       Uses  an  extension  of the 1-wire design from iButtonLink company that
156       associated 1-wire physical connections with a unique  1-wire  code.  If
157       the  connection is behind a Link Locator the locator will show a unique
158       8-byte number (16 character hexadecimal) starting with family code FE.
159       If no Link Locator is between the device and the  master,  the  locator
160       field will be all FF.
161       r locator is the locator in reverse order.
162
163   present (DEPRECATED)
164       read-only, yes-no
165       Is the device currently present on the 1-wire bus?
166
167   type
168       read-only, ascii
169       Part  name  assigned by Dallas Semi. E.g.  DS2401 Alternative packaging
170       (iButton vs chip) will not be distiguished.
171

ALARMS

173       None.
174

DESCRIPTION

176   1-Wire
177       1-wire is a wiring protocol and series of devices designed and manufac‐
178       tured  by  Dallas  Semiconductor, Inc. The bus is a low-power low-speed
179       low-connector scheme where the data line can also provide power.
180
181       Each device is uniquely and unalterably  numbered  during  manufacture.
182       There  are a wide variety of devices, including memory, sensors (humid‐
183       ity, temperature, voltage, contact, current), switches, timers and data
184       loggers.  More complex devices (like thermocouple sensors) can be built
185       with these basic devices. There are also 1-wire devices that  have  en‐
186       cryption included.
187
188       The  1-wire  scheme uses a single bus master and multiple slaves on the
189       same wire. The bus master initiates all communication. The  slaves  can
190       be individually discovered and addressed using their unique ID.
191
192       Bus  masters come in a variety of configurations including serial, par‐
193       allel, i2c, network or USB adapters.
194
195   OWFS design
196       OWFS is a suite of programs that designed to make the  1-wire  bus  and
197       its  devices easily accessible. The underlying principle is to create a
198       virtual filesystem, with the unique ID being the directory, and the in‐
199       dividual  properties of the device are represented as simple files that
200       can be read and written.
201
202       Details of the individual slave or master design are  hidden  behind  a
203       consistent interface. The goal is to provide an easy set of tools for a
204       software designer to create monitoring or control  applications.  There
205       are some performance enhancements in the implementation, including data
206       caching, parallel access to bus masters, and aggregation of device com‐
207       munication.  Still the fundamental goal has been ease of use, flexibil‐
208       ity and correctness rather than speed.
209
210   DS2780
211       The DS2780 (3) is a battery charging controller. It has elaborate algo‐
212       rithms for estimating battery capacity.
213
214       A  number of interesting devices can be built with the DS2780 including
215       thermocouples. Support for thermocouples in built  into  the  software,
216       using the embedded thermister as the cold junction temperature.
217

ADDRESSING

219       All  1-wire  devices are factory assigned a unique 64-bit address. This
220       address is of the form:
221
222       Family Code
223              8 bits
224
225       Address
226              48 bits
227
228       CRC    8 bits
229
230       Addressing under OWFS is in hexadecimal, of form:
231
232              01.123456789ABC
233
234       where 01 is an example 8-bit family code, and 12345678ABC is an example
235       48 bit address.
236
237       The  dot  is  optional,  and the CRC code can included. If included, it
238       must be correct.
239

DATASHEET

241       http://pdfserv.maxim-ic.com/en/ds/DS2780.pdf
242       http://pdfserv.maxim-ic.com/en/ds/DS2788.pdf
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AVAILABILITY

306       http://www.owfs.org
307

AUTHOR

309       Paul Alfille (paul.alfille@gmail.com)
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313OWFS Manpage                         2003                            DS2760(3)