DS2437(3)

1DS2437(3)                    One-Wire File System                    DS2437(3)
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NAME

6       DS2437 - Smart Battery Monitor
7

SYNOPSIS

9       Temperature Voltages and Memory.
10
11       1E  [.]XXXXXXXXXXXX[XX][/[  current  | date | disconnect/date | discon‐
12       nect/udate   |   endcharge/date   |   endcharge/udate   |   Ienable   |
13       pages/page.[0-7|ALL] | temperature | udate | VAD | VDD | address | crc8
14       | id | locator | r_address | r_id | r_locator | type ]]
15

FAMILY CODE

17       1E
18

SPECIAL PROPERTIES

20   date
21       read-write, ascii
22       26 character date representation of the counter value. Increments  once
23       per second.
24       Setting date to a null string will put the current system time.
25       Accepted date formats are:
26         Sat[urday] March 12 12:23:59 2001
27         Apr[il] 4 9:34:56 2002
28         3/23/04 23:34:57
29         current locale setting (your system's format)
30
31   current
32       read-only, integer
33       Current   reading.  Actual  current  depends  on  Rsens  resistor  (see
34       datasheet).
35       The formula for current is I = current /(4096*Rsens)
36       with units in Amps and Ohms.
37       Current measurement will be temporarily enabled (see Ienable )  if  not
38       currently enabled (pun intended) for this reading.
39
40   disconnect/date
41       read-write, ascii
42       26  character  date  representation of the disconnect/udate value. Time
43       when the battery pack waws removed from the charger. Format is the same
44       as the date property.
45
46   disconnect/udate
47       read-write, unsigned integer
48       Representation of disconnect/date as a number. See udate for details.
49
50   endcharge/date
51       read-write, ascii
52       26  character  date representation of the endcharge/udate value. Format
53       is the same as the date property.
54
55   endcharge/udate
56       read-write, unsigned integer
57       Representation of endcharge/date as a number. See udate for details.
58
59   Ienable
60       read-write, unsigned integer
61       Status of current monitoring. When enabled,  current  sensing  is  per‐
62       formed 36.41 times/second. Values of Ienable are:
63
64       0      no current conversion
65
66       1      current conversion enabled
67
68       2      current conversion and accumulation
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70       3      current conversion and accumulation with EEPROM backup
71
72   pages/page.0 ... pages/page.7 pages/page.ALL
73       read-write, binary
74       Memory  is  split  into 8 pages of 8 bytes each. Only the pages 3-7 are
75       really available, and some of that appears  to  be  reserved.  See  the
76       datasheet for details.
77       ALL is an aggregate of the pages. Each page is accessed sequentially.
78
79   temperature
80       read-only, floating point
81       Temperature  read  by the chip at high resolution (~13 bits). Units are
82       selected from the invoking command line. See owfs(1) or owhttpd(1)  for
83       choices. Default is Celsius.  Conversion takes ~20 msec.
84
85   udate
86       read-write, unsigned integer
87       Time represented as a number.  udate increments once per second.
88       Usually set to unix time standard: number of seconds since Jan 1, 1970.
89       The date field will be the unix representation (ascii  text)  of  udate
90       and setting either will change the other.
91
92   VAD VDD
93       read-only, floating point
94       Voltage  read  (~10 bits) at the one of the chip's two supply voltages.
95       Range VDD= 2.4V to 10V, VAD=1.5 to 10V.
96

STANDARD PROPERTIES

98   address
99   r_address
100       read-only, ascii
101       The entire 64-bit unique ID. Given as  upper  case  hexidecimal  digits
102       (0-9A-F).
103       address starts with the family code
104       r address is the address in reverse order, which is often used in other
105       applications and labeling.
106
107   crc8
108       read-only, ascii
109       The 8-bit error correction portion. Uses cyclic redundancy check.  Com‐
110       puted  from  the  preceding  56  bits of the unique ID number. Given as
111       upper case hexadecimal digits (0-9A-F).
112
113   family
114       read-only, ascii
115       The 8-bit family code. Unique to each type of device.  Given  as  upper
116       case hexadecimal digits (0-9A-F).
117
118   id
119   r_id
120       read-only, ascii
121       The 48-bit middle portion of the unique ID number. Does not include the
122       family code or CRC. Given as upper case hexadecimal digits (0-9A-F).
123       r id is the id in reverse order, which is often used in other  applica‐
124       tions and labeling.
125
126   locator
127   r_locator
128       read-only, ascii
129       Uses  an  extension  of the 1-wire design from iButtonLink company that
130       associated 1-wire physical connections with a unique  1-wire  code.  If
131       the  connection is behind a Link Locator the locator will show a unique
132       8-byte number (16 character hexadecimal) starting with family code FE.
133       If no Link Locator is between the device and the  master,  the  locator
134       field will be all FF.
135       r locator is the locator in reverse order.
136
137   present (DEPRECATED)
138       read-only, yes-no
139       Is the device currently present on the 1-wire bus?
140
141   type
142       read-only, ascii
143       Part  name  assigned by Dallas Semi. E.g.  DS2401 Alternative packaging
144       (iButton vs chip) will not be distiguished.
145

ALARMS

147       None.
148

DESCRIPTION

150   1-Wire
151       1-wire is a wiring protocol and series of devices designed and manufac‐
152       tured  by  Dallas  Semiconductor, Inc. The bus is a low-power low-speed
153       low-connector scheme where the data line can also provide power.
154
155       Each device is uniquely and unalterably  numbered  during  manufacture.
156       There  are a wide variety of devices, including memory, sensors (humid‐
157       ity, temperature, voltage, contact, current), switches, timers and data
158       loggers.  More complex devices (like thermocouple sensors) can be built
159       with these basic devices. There  are  also  1-wire  devices  that  have
160       encryption included.
161
162       The  1-wire  scheme uses a single bus master and multiple slaves on the
163       same wire. The bus master initiates all communication. The  slaves  can
164       be individually discovered and addressed using their unique ID.
165
166       Bus  masters come in a variety of configurations including serial, par‐
167       allel, i2c, network or USB adapters.
168
169   OWFS design
170       OWFS is a suite of programs that designed to make the  1-wire  bus  and
171       its  devices easily accessible. The underlying principle is to create a
172       virtual filesystem, with the unique ID being  the  directory,  and  the
173       individual  properties  of  the  device are represented as simple files
174       that can be read and written.
175
176       Details of the individual slave or master design are  hidden  behind  a
177       consistent interface. The goal is to provide an easy set of tools for a
178       software designer to create monitoring or control  applications.  There
179       are some performance enhancements in the implementation, including data
180       caching, parallel access to bus masters, and aggregation of device com‐
181       munication.  Still the fundamental goal has been ease of use, flexibil‐
182       ity and correctness rather than speed.
183
184   DS2437
185       The DS2437 (3) is an obsolete version of the DS2438 (3)  battery  chip.
186       Current  sensing is available, but not implemented. The major advantage
187       compared to the DS2436 is that two voltages can be read, allowing  cor‐
188       recting circuit nmeasurements to supply voltage and temperature. A bet‐
189       ter comparison is the DS276x family of chips.
190

ADDRESSING

192       All 1-wire devices are factory assigned a unique 64-bit  address.  This
193       address is of the form:
194
195       Family Code
196              8 bits
197
198       Address
199              48 bits
200
201       CRC    8 bits
202
203       Addressing under OWFS is in hexadecimal, of form:
204
205              01.123456789ABC
206
207       where 01 is an example 8-bit family code, and 12345678ABC is an example
208       48 bit address.
209
210       The dot is optional, and the CRC code can  included.  If  included,  it
211       must be correct.
212

DATASHEET

214       http://pdfserv.maxim-ic.com/en/ds/DS2437.pdf
215       http://pdfserv.maxim-ic.com/en/an/humsensor.pdf
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AVAILABILITY

278       http://www.owfs.org
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AUTHOR

281       Paul Alfille (paul.alfille@gmail.com)
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285OWFS Manpage                         2003                            DS2437(3)