1DS28EC20(3) One-Wire File System DS28EC20(3)
2
6 DS28EC20 - EEPROM (20 kBit)
7
9 Erasable programmable read-only memory (EEPROM)
10 43 [.]XXXXXXXXXXXX[XX][/[ memory | pages/page.[0-79|ALL] | address |
12 crc8 | id | locator | r_address | r_id | r_locator | type ]]
13
15 23 DS28EC20
16
18 memory
19 read-write, binary
20 512 bytes of memory. Initially all bits are set to 1. Writing zero per‐
21 manently alters the memory.
22 pages/page.0 ... pages/page.79 pages/page.ALL
24 read-write, yes-no
25 Memory is split into 80 pages of 32 bytes each. ALL is an aggregate of
26 the pages. Each page is accessed sequentially.
27
29 address
30 r_address
31 read-only, ascii
32 The entire 64-bit unique ID. Given as upper case hexadecimal digits
33 (0-9A-F).
34 address starts with the family code
35 r address is the address in reverse order, which is often used in other
36 applications and labeling.
37 crc8
39 read-only, ascii
40 The 8-bit error correction portion. Uses cyclic redundancy check. Com‐
41 puted from the preceding 56 bits of the unique ID number. Given as up‐
42 per case hexadecimal digits (0-9A-F).
43 family
45 read-only, ascii
46 The 8-bit family code. Unique to each type of device. Given as upper
47 case hexadecimal digits (0-9A-F).
48 id
50 r_id
51 read-only, ascii
52 The 48-bit middle portion of the unique ID number. Does not include the
53 family code or CRC. Given as upper case hexadecimal digits (0-9A-F).
54 r id is the id in reverse order, which is often used in other applica‐
55 tions and labeling.
56 locator
58 r_locator
59 read-only, ascii
60 Uses an extension of the 1-wire design from iButtonLink company that
61 associated 1-wire physical connections with a unique 1-wire code. If
62 the connection is behind a Link Locator the locator will show a unique
63 8-byte number (16 character hexadecimal) starting with family code FE.
64 If no Link Locator is between the device and the master, the locator
65 field will be all FF.
66 r locator is the locator in reverse order.
67 present (DEPRECATED)
69 read-only, yes-no
70 Is the device currently present on the 1-wire bus?
71 type
73 read-only, ascii
74 Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging
75 (iButton vs chip) will not be distiguished.
76
78 None.
79
81 1-Wire
82 1-wire is a wiring protocol and series of devices designed and manufac‐
83 tured by Dallas Semiconductor, Inc. The bus is a low-power low-speed
84 low-connector scheme where the data line can also provide power.
85 Each device is uniquely and unalterably numbered during manufacture.
87 There are a wide variety of devices, including memory, sensors (humid‐
88 ity, temperature, voltage, contact, current), switches, timers and data
89 loggers. More complex devices (like thermocouple sensors) can be built
90 with these basic devices. There are also 1-wire devices that have en‐
91 cryption included.
92 The 1-wire scheme uses a single bus master and multiple slaves on the
94 same wire. The bus master initiates all communication. The slaves can
95 be individually discovered and addressed using their unique ID.
96 Bus masters come in a variety of configurations including serial, par‐
98 allel, i2c, network or USB adapters.
99 OWFS design
101 OWFS is a suite of programs that designed to make the 1-wire bus and
102 its devices easily accessible. The underlying principle is to create a
103 virtual filesystem, with the unique ID being the directory, and the in‐
104 dividual properties of the device are represented as simple files that
105 can be read and written.
106 Details of the individual slave or master design are hidden behind a
108 consistent interface. The goal is to provide an easy set of tools for a
109 software designer to create monitoring or control applications. There
110 are some performance enhancements in the implementation, including data
111 caching, parallel access to bus masters, and aggregation of device com‐
112 munication. Still the fundamental goal has been ease of use, flexibil‐
113 ity and correctness rather than speed.
114 DS28EC20
116 The DS28EC20 (3) is used for storing memory which should be available
117 even after a reset or power off. It's main advantage is for audit
118 trails (i.e. a digital purse). OWFS system handles this automatically.
119
121 All 1-wire devices are factory assigned a unique 64-bit address. This
122 address is of the form:
123 Family Code
125 8 bits
126 Address
128 48 bits
129 CRC 8 bits
131 Addressing under OWFS is in hexadecimal, of form:
133 01.123456789ABC
135 where 01 is an example 8-bit family code, and 12345678ABC is an example
137 48 bit address.
138 The dot is optional, and the CRC code can included. If included, it
140 must be correct.
141
143 http://datasheets.maxim-ic.com/en/ds/DS28EC20.pdf
144
146 Programs
147 owfs (1) owhttpd (1) owftpd (1) owserver (1) owdir (1) owread (1)
148 owwrite (1) owpresent (1) owtap (1)
149 Configuration and testing
151 owfs (5) owtap (1) owmon (1)
152 Language bindings
154 owtcl (3) owperl (3) owcapi (3)
155 Clocks
157 DS1427 (3) DS1904 (3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3)
158 DS2417 (3)
159 ID
161 DS2401 (3) DS2411 (3) DS1990A (3)
162 Memory
164 DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3)
165 DS1995 (3) DS1996 (3) DS2430A (3) DS2431 (3) DS2433 (3) DS2502 (3)
166 DS2506 (3) DS28E04 (3) DS28EC20 (3)
167 Switches
169 DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3) In‐
170 fernoEmbedded (3)
171 Temperature
173 DS1822 (3) DS1825 (3) DS1820 (3) DS18B20 (3) DS18S20 (3) DS1920 (3)
174 DS1921 (3) DS1821 (3) DS28EA00 (3) DS28E04 (3) EDS0064 (3) EDS0065 (3)
175 EDS0066 (3) EDS0067 (3) EDS0068 (3) EDS0071 (3) EDS0072 (3) MAX31826
176 [1m(3)
177 Humidity
179 DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (3)
180 Voltage
182 DS2450 (3)
183 Resistance
185 DS2890 (3)
186 Multifunction (current, voltage, temperature)
188 DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3)
189 DS2760 (3) DS2770 (3) DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)
190 Counter
192 DS2423 (3)
193 LCD Screen
195 LCD (3) DS2408 (3)
196 Crypto
198 DS1977 (3)
199 Pressure
201 DS2406 (3) TAI8570 (3) EDS0066 (3) EDS0068 (3)
202 Moisture
204 EEEF (3) DS2438 (3)
205
207 http://www.owfs.org
208
210 Christian Magnusson (mag@mag.cx)
211OWFS Manpage 2003 DS28EC20(3)