DS1977(3)

1DS1977(3)                    One-Wire File System                    DS1977(3)
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NAME

6       DS1977 - Password Protected 32kbit Memory iButton
7

SYNOPSIS

9       Non-volatile memory.
10
11       37  [.]XXXXXXXXXXXX[XX][/[  memory  | pages/page.[0-510|ALL] | set_num‐
12       ber/full | set_number/read | set_password/enabled | set_password/full |
13       set_password/read  |  use_number/full  |  use_number/read  |  use_pass‐
14       word/full | use_password/read |  address  |  crc8  |  id  |  locator  |
15       r_address | r_id | r_locator | type ]]
16

FAMILY CODE

18       37 DS1977
19

SPECIAL PROPERTIES

21   memory
22       read-write, binary
23       32704 bytes of memory. Possibly protected by a password.
24
25   pages/page.0 ... pages/page.510 pages/page.ALL
26       read-write, binary
27       Memory  is  split into 511 pages of 64 bytes each.  ALL is an aggregate
28       of the pages. Each page is accessed sequentially.
29
30   set_number/full set_number/read
31       write-only, ascii
32       Passwords  entered  as  numbers,  either  decimal,  or  hex   of   form
33       0x0123456789ABCDEF. Handled the same as set_password/xxx
34
35   set_password/enable
36       read-write, yes-no
37       Turn  on/off  password protection for the DS1977, or return the current
38       state.
39
40   set_password/full set_password/read
41       write-only, binary
42       Passwords (8 byte values) that allow read or full access to the  DS1977
43       memory.  The  password set by set_password/xxx are stored in the DS1977
44       and locally in the program as well (as  if  use_password/xxx  was  also
45       called).
46
47   use_password/full use_password/read
48       write-only, binary
49       Passwords  (8 byte values) that allow read or full access to the DS1977
50       memory. The password set by
51
52   use_number/full use_number/read
53       write-only, ascii
54       Passwords  entered  as  numbers,  either  decimal,  or  hex   of   form
55       0x0123456789ABCDEF. Handled the same as use_password/xxx
56
57   use_password/full use_password/read
58       write-only, binary
59       Passwords  (8 byte values) that allow read or full access to the DS1977
60       memory. The password set by use_password/xxx are stored in the  program
61       and  must match the passwords stored in the DS1977. Changing the DS1977
62       passwords using set_password/xxx will  change  these  values  as  well.
63       use_password/xxx are stored in the program and must match the passwords
64       stored in the DS1977. Changing the  DS1977  passwords  using  set_pass‐
65       word/xxx will change these values as well.
66

STANDARD PROPERTIES

68   address
69   r_address
70       read-only, ascii
71       The  entire  64-bit  unique  ID. Given as upper case hexidecimal digits
72       (0-9A-F).
73       address starts with the family code
74       r address is the address in reverse order, which is often used in other
75       applications and labeling.
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77   crc8
78       read-only, ascii
79       The  8-bit error correction portion. Uses cyclic redundancy check. Com‐
80       puted from the preceding 56 bits of the  unique  ID  number.  Given  as
81       upper case hexidecimal digits (0-9A-F).
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83   family
84       read-only, ascii
85       The  8-bit  family  code. Unique to each type of device. Given as upper
86       case hexidecimal digits (0-9A-F).
87
88   id
89   r_id
90       read-only, ascii
91       The 48-bit middle portion of the unique ID number. Does not include the
92       family code or CRC. Given as upper case hexidecimal digits (0-9A-F).
93       r  id is the id in reverse order, which is often used in other applica‐
94       tions and labeling.
95
96   locator
97   r_locator
98       read-only, ascii
99       Uses an extension of the 1-wire design from  iButtonLink  company  that
100       associated  1-wire  physical  connections with a unique 1-wire code. If
101       the connection is behind a Link Locator the locator will show a  unique
102       8-byte number (16 character hexidecimal) starting with family code FE.
103       If  no  Link  Locator is between the device and the master, the locator
104       field will be all FF.
105       r locator is the locator in reverse order.
106
107   present (DEPRECATED)
108       read-only, yes-no
109       Is the device currently present on the 1-wire bus?
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111   type
112       read-only, ascii
113       Part name assigned by Dallas Semi. E.g.  DS2401  Alternative  packaging
114       (iButton vs chip) will not be distiguished.
115

ALARMS

117       None.
118

DESCRIPTION

120   1-Wire
121       1-wire is a wiring protocol and series of devices designed and manufac‐
122       tured by Dallas Semiconductor, Inc. The bus is  a  low-power  low-speed
123       low-connector scheme where the data line can also provide power.
124
125       Each  device  is  uniquely and unalterably numbered during manufacture.
126       There are a wide variety of devices, including memory, sensors  (humid‐
127       ity, temperature, voltage, contact, current), switches, timers and data
128       loggers. More complex devices (like thermocouple sensors) can be  built
129       with  these  basic  devices.  There  are  also 1-wire devices that have
130       encryption included.
131
132       The 1-wire scheme uses a single bus master and multiple slaves  on  the
133       same  wire.  The bus master initiates all communication. The slaves can
134       be individually discovered and addressed using their unique ID.
135
136       Bus masters come in a variety of configurations including serial,  par‐
137       allel, i2c, network or USB adapters.
138
139   OWFS design
140       OWFS  is  a  suite of programs that designed to make the 1-wire bus and
141       its devices easily accessible. The underlying principle is to create  a
142       virtual  filesystem,  with  the  unique ID being the directory, and the
143       individual properties of the device are  represented  as  simple  files
144       that can be read and written.
145
146       Details  of  the  individual slave or master design are hidden behind a
147       consistent interface. The goal is to provide an easy set of tools for a
148       software  designer  to create monitoring or control applications. There
149       are some performance enhancements in the implementation, including data
150       caching, parallel access to bus masters, and aggregation of device com‐
151       munication. Still the fundemental goal has been ease of use,  flexibil‐
152       ity and correctness rather than speed.
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154   DS1977
155       The DS1977 (3) is an iButton with static memory that is optionally pro‐
156       tected by a password.
157

ADDRESSING

159       All 1-wire devices are factory assigned a unique 64-bit  address.  This
160       address is of the form:
161
162       Family Code
163              8 bits
164
165       Address
166              48 bits
167
168       CRC    8 bits
169
170       Addressing under OWFS is in hexidecimal, of form:
171
172              01.123456789ABC
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174       where 01 is an example 8-bit family code, and 12345678ABC is an example
175       48 bit address.
176
177       The dot is optional, and the CRC code can  included.  If  included,  it
178       must be correct.
179

DATASHEET

181       http://pdfserv.maxim-ic.com/en/ds/DS1977.pdf
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AVAILABILITY

244       http://www.owfs.org
245

AUTHOR

247       Paul Alfille (paul.alfille@gmail.com)
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251OWFS Manpage                         2003                            DS1977(3)