DS2502(3)

1DS2502(3)                    One-Wire File System                    DS2502(3)
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NAME

6       DS2502 - Add-Only Memory (1 kBit)
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8       DS2502-E48, DS2502-UNW
9              - 48-bit Node Address Chip, UniqueWare Add-Only Memory (1 kBit)
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11       DS1982, DS1982U
12              - Add-Only iButton (1 kBit), UniqueWare iButton (1 kBit)
13

SYNOPSIS

15       EPROM add-only memory.
16
17       09  [.]XXXXXXXXXXXX[XX][/[  memory  |  pages/page.[0-3|ALL] | address |
18       crc8 | id | locator | r_address | r_id | r_locator | type ]]
19
20       89   [.]XXXXXXXXXXXX[XX][/[    mac_e    |    mac_fw    |    memory    |
21       pages/page.[0-3|ALL]  |  project  |  address  |  crc8  | id | locator |
22       r_address | r_id | r_locator | type ]]
23

FAMILY CODE

25       09     DS2502 DS1982
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27       89     DS2502-UNW DS2502-E48 DS1982U
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SPECIAL PROPERTIES

30   mac_e mac_fw
31       read-only, binary
32       64 bit or 80 bit media access control number. Unique, and unrelated  to
33       the  1-wire  address.  It  is  apparently used for ethernet or FireWire
34       addressing, respectively.
35
36   memory
37       read-write, binary
38       128 bytes of memory. Initially all bits are set to 1. Writing zero per‐
39       manently alters the memory.
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41   pages/page.0 ... pages/page.3 pages/page.ALL
42       read-write, yes-no
43       Memory  is split into 4 pages of 32 bytes each.  ALL is an aggregate of
44       the pages. Each page is accessed sequentially.
45
46   project
47       read-only, binary
48       32 bit project id. Constant 0x0000 for  ethernet  and   0x00001128  for
49       firewire. See Datasheets.
50

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.
60
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 hexidecimal 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 hexidecimal 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 hexidecimal 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 hexidecimal) 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?
94
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.
99

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.
119
120       Bus masters come in a variety of configurations including serial,  par‐
121       allel, i2c, network or USB adapters.
122
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 fundemental goal has been ease of use,  flexibil‐
136       ity and correctness rather than speed.
137
138   DS2502 DS1982
139       The  DS2502  (3)  is used for write-once incremental storage. It's main
140       advantage is for audit trails (i.e. a digital purse).
141
142       The DS2502-E48 and DS2502-UNW are  some  of  the  UniqueWare  class  of
143       devices.  Some  of  the memory was preprogramed at the factory. See the
144       datasheet for specifics.  The DS2502 , DS2505 , and  DS2506  differ  in
145       their  function  by  the  amount  of on-board memory they possess. (The
146       internal protocols are slightly different, but the OWFS system  handles
147       this automatically.
148

ADDRESSING

150       All  1-wire  devices are factory assigned a unique 64-bit address. This
151       address is of the form:
152
153       Family Code
154              8 bits
155
156       Address
157              48 bits
158
159       CRC    8 bits
160
161       Addressing under OWFS is in hexidecimal, of form:
162
163              01.123456789ABC
164
165       where 01 is an example 8-bit family code, and 12345678ABC is an example
166       48 bit address.
167
168       The  dot  is  optional,  and the CRC code can included. If included, it
169       must be correct.
170

DATASHEET

172       http://pdfserv.maxim-ic.com/en/ds/DS2502.pdf
173       http://pdfserv.maxim-ic.com/en/ds/DS2502-E48.pdf
174       http://pdfserv.maxim-ic.com/en/ds/DS2502-UNW-DS2506S-UNW.pdf
175       http://pdfserv.maxim-ic.com/en/ds/DS1982-F3-DS1982-F5.pdf
176       http://pdfserv.maxim-ic.com/en/ds/DS1982U-DS1986U.pdf
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AVAILABILITY

239       http://www.owfs.org
240

AUTHOR

242       Paul Alfille (paul.alfille@gmail.com)
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246OWFS Manpage                         2003                            DS2502(3)