DS2423(3)

1DS2423(3)                    One-Wire File System                    DS2423(3)
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NAME

6       DS2423 - 4kbit 1-Wire RAM with Counter
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SYNOPSIS

9       RAM and counters.
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11       1D     [.]XXXXXXXXXXXX[XX][/[     counter.[A|B|ALL]    |    memory    |
12       pages/page.[0-15|ALL] | pages/count.[0-15|ALL] | address | crc8 | id  |
13       locator | r_address | r_id | r_locator | type ]]
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FAMILY CODE

16       1D
17

SPECIAL PROPERTIES

19   counter.A counter.B counter.ALL
20       read-only, unsigned integer
21       Debounced  external  counter.  Associated  with RAM page.14 and page.15
22       Note: counter increments only. It is reset when the chip loses power.
23       ALL returns the two values, separated by a comma. They are read sequen‐
24       tially.
25
26       The  property  was  called counters prior to OWFS version 2.9p1 and the
27       old name is invisibly recognized for backwards compatibility.
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29   memory
30       read-write, binary
31       512 bytes of memory.
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33   pages/page.0 ... pages/page.15 pages/page.ALL
34       read-write, binary
35       Memory is split into 16 pages of 32 bytes each. Memory is RAM, contents
36       are  lost  when  power is lost.  ALL is an aggregate of the pages. Each
37       page is accessed sequentially.
38
39   pages/count.0 ... pages/count.15 pages/count.ALL
40       read-only, unsigned integer
41
42       Write access to each page of memory. Actually only page.12 and  page.13
43       have write counters.
44       page14  and  page.15 ´s counters are associated with the external coun‐
45       ters.A and counters.B triggers.
46       The  value   0xFFFFFFFF   is   returned   for   pages/count.0   through
47       pages/count.11
48       ALL  is  an  aggregate  of  the counters, comma separated. Each page is
49       accessed sequentially.
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STANDARD PROPERTIES

52   address
53   r_address
54       read-only, ascii
55       The entire 64-bit unique ID. Given as  upper  case  hexidecimal  digits
56       (0-9A-F).
57       address starts with the family code
58       r address is the address in reverse order, which is often used in other
59       applications and labeling.
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61   crc8
62       read-only, ascii
63       The 8-bit error correction portion. Uses cyclic redundancy check.  Com‐
64       puted  from  the  preceding  56  bits of the unique ID number. Given as
65       upper case hexadecimal digits (0-9A-F).
66
67   family
68       read-only, ascii
69       The 8-bit family code. Unique to each type of device.  Given  as  upper
70       case hexadecimal digits (0-9A-F).
71
72   id
73   r_id
74       read-only, ascii
75       The 48-bit middle portion of the unique ID number. Does not include the
76       family code or CRC. Given as upper case hexadecimal digits (0-9A-F).
77       r id is the id in reverse order, which is often used in other  applica‐
78       tions and labeling.
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80   locator
81   r_locator
82       read-only, ascii
83       Uses  an  extension  of the 1-wire design from iButtonLink company that
84       associated 1-wire physical connections with a unique  1-wire  code.  If
85       the  connection is behind a Link Locator the locator will show a unique
86       8-byte number (16 character hexadecimal) starting with family code FE.
87       If no Link Locator is between the device and the  master,  the  locator
88       field will be all FF.
89       r locator is the locator in reverse order.
90
91   present (DEPRECATED)
92       read-only, yes-no
93       Is the device currently present on the 1-wire bus?
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95   type
96       read-only, ascii
97       Part  name  assigned by Dallas Semi. E.g.  DS2401 Alternative packaging
98       (iButton vs chip) will not be distiguished.
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ALARMS

101       None.
102

DESCRIPTION

104   1-Wire
105       1-wire is a wiring protocol and series of devices designed and manufac‐
106       tured  by  Dallas  Semiconductor, Inc. The bus is a low-power low-speed
107       low-connector scheme where the data line can also provide power.
108
109       Each device is uniquely and unalterably  numbered  during  manufacture.
110       There  are a wide variety of devices, including memory, sensors (humid‐
111       ity, temperature, voltage, contact, current), switches, timers and data
112       loggers.  More complex devices (like thermocouple sensors) can be built
113       with these basic devices. There  are  also  1-wire  devices  that  have
114       encryption included.
115
116       The  1-wire  scheme uses a single bus master and multiple slaves on the
117       same wire. The bus master initiates all communication. The  slaves  can
118       be individually discovered and addressed using their unique ID.
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120       Bus  masters come in a variety of configurations including serial, par‐
121       allel, i2c, network or USB adapters.
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123   OWFS design
124       OWFS is a suite of programs that designed to make the  1-wire  bus  and
125       its  devices easily accessible. The underlying principle is to create a
126       virtual filesystem, with the unique ID being  the  directory,  and  the
127       individual  properties  of  the  device are represented as simple files
128       that can be read and written.
129
130       Details of the individual slave or master design are  hidden  behind  a
131       consistent interface. The goal is to provide an easy set of tools for a
132       software designer to create monitoring or control  applications.  There
133       are some performance enhancements in the implementation, including data
134       caching, parallel access to bus masters, and aggregation of device com‐
135       munication.  Still the fundamental goal has been ease of use, flexibil‐
136       ity and correctness rather than speed.
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138   DS2423
139       The DS2423 (3) is used for its counters. The internal counters (associ‐
140       ated with pages 12 and 13) can detect memory tampering.
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142       The external counters A and B page been used in circuit design, such as
143       a wind anometer.  OWFS system handles this automatically.
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ADDRESSING

146       All 1-wire devices are factory assigned a unique 64-bit  address.  This
147       address is of the form:
148
149       Family Code
150              8 bits
151
152       Address
153              48 bits
154
155       CRC    8 bits
156
157       Addressing under OWFS is in hexadecimal, of form:
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159              01.123456789ABC
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161       where 01 is an example 8-bit family code, and 12345678ABC is an example
162       48 bit address.
163
164       The dot is optional, and the CRC code can  included.  If  included,  it
165       must be correct.
166

DATASHEET

168       http://pdfserv.maxim-ic.com/en/ds/DS2423.pdf
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AVAILABILITY

231       http://www.owfs.org
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AUTHOR

234       Paul Alfille (paul.alfille@gmail.com)
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238OWFS Manpage                         2003                            DS2423(3)