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Table of Contents

Name

DS1991 - 1152bit MultiKey iButton

Synopsis

Non-volatile memory with password protection.

02 [.]XXXXXXXXXXXX[XX][/[ memory | pages/ident.[0-2|ALL] | pages/page.[0-2|ALL] | pages/password.[0-2|ALL] | settings/ident.[0-2|ALL] | settings/page.[0-2|ALL] | settings/password.[0-2|ALL] | settings/change_password.[0-2|ALL] | settings/reset_password.[0-2|ALL] | address | crc8 | id | locator | present | r_address | r_id | r_locator | type ]]

Family Code

02

Special Properties

memory

read-write, binary
144 bytes of non-volatile memory. Reading and writing (with offset) to the files will only work if currently used password is correct for all 3 pages.

pages/page.0 pages/page.1.html pages/page.2.html pages/page.ALL

read-write, binary
Memory is split into 3 pages of 48 bytes each. ALL is an aggregate of the pages. Each page is accessed sequentially. If currently used password is incorrect, random data will be returned when reading a page.

pages/password.0 pages/password.1.html pages/password.2.html pages/password.ALL

write, binary
Memory is split into 3 pages and each page has a unique password (8 bytes). ALL is an aggregate of the password. Each page is accessed sequentially. Writing to this file will set the currently used password when accessing memory in corresponding page. If the password is wrong, random data will be returned when reading memory.

pages/ident.0 pages/ident.1.html pages/ident.2.html pages/ident.ALL

read-write, binary
Memory is split into 3 pages and each page has a unique identification (8 bytes). ALL is an aggregate of the ident. Each page is accessed sequentially. Identification will return correct result even if currently used password is incorrect.

settings/page.0 settings/page.1.html settings/page.2.html settings/page.ALL

read-write, binary
Memory is split into 3 pages of 48 bytes each. ALL is an aggregate of the pages. Each page is accessed sequentially. If currently used password is incorrect, random data will be returned when reading a page. (same as pages/page.*)

settings/ident.0 settings/ident.1.html settings/ident.2.html settings/ident.ALL

read-write, binary
Memory is split into 3 pages and each page has a unique identification (8 bytes). ALL is an aggregate of the ident. Each page is accessed sequentially. Identification will return correct result even if currently used password is incorrect. (same as pages/ident.*)

settings/password.0 settings/password.1.html settings/password.2.html settings/password.ALL

write, binary
Memory is split into 3 pages and each page has a unique password (8 bytes). ALL is an aggregate of the password. Each page is accessed sequentially. Writing to this file will set the currently used password when accessing memory in corresponding page. If the password is wrong, random data will be returned when reading memory. (same as pages/password.*)

settings/reset_password.0 settings/reset_password.1.html settings/reset_password.2.html settings/reset_password.ALL

write, binary
Memory is split into 3 pages and each page has a unique password (8 bytes). ALL is an aggregate of the ident. Each page is accessed sequentially. Writing to this file will reset the password on the page. NOTE: All data in corresponding page will be deleted!

settings/change_password.0 settings/change_password.1.html settings/change_password.2.html settings/change_password.ALL

write, binary
Memory is split into 3 pages and each page has a unique password (8 bytes). ALL is an aggregate of the ident. Each page is accessed sequentially. Writing to this file will change the password on the page. NOTE: Currently used password have to be set to correct password before changing password. Data in the corresponding page is NOT effected.

Standard Properties

address

r_address

read-only, ascii
The entire 64-bit unique ID. Given as upper case hexidecimal digits (0-9A-F).
address starts with the family code
r address is the address in reverse order, which is often used in other applications and labeling.

crc8

read-only, ascii
The 8-bit error correction portion. Uses cyclic redundancy check. Computed from the preceeding 56 bits of the unique ID number. Given as upper case hexidecimal digits (0-9A-F).

family

read-only, ascii
The 8-bit family code. Unique to each type of device. Given as upper case hexidecimal digits (0-9A-F).

id

r_id

read-only, ascii
The 48-bit middle portion of the unique ID number. Does not include the family code or CRC. Given as upper case hexidecimal digits (0-9A-F).
r id is the id in reverse order, which is often used in other applications and labeling.

locator

r_locator

read-only, ascii
Uses an extension of the 1-wire design from iButtonLink company that associated 1-wire physical connections with a unique 1-wire code. If the connection is behind a Link Locator the locator will show a unique 8-byte number (16 character hexidecimal) starting with family code FE.
If no Link Locator is between the device and the master, the locator field will be all FF.
r locator is the locator in reverse order.

present

read-only, yes-no
Is the device currently present on the 1-wire bus?
Note, this means that each hex byte (2 characters) is reversed, not the text string.

type

read-only, ascii
Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging (iButton vs chip) will not be distiguished.

Alarms

None.

Description

1-Wire

1-wire is a wiring protocol and series of devices designed and manufactured by Dallas Semicondictor, Inc. The bus is a low-power low-speed low-connector scheme where the data line can also provide power.

Each device is uniquely unalterably numbered during manufacture. There is a wide variety of devices, including memory, sensors (humidity, temperature, voltage, contact, current), switches, timers, loggers, and more complex devices (like thermocouple sensors) can be built wit hte basic devices. There are also 1-wire devices that have encryption included.

The 1-wire bus is accessed via one of a number of serial, parallel or USB adapters.

OWFS design

OWFS is a suite of programs that fundementally make the 1-wire bus and its devices easily accessible. The underlying priciple is to create a virtual filesystem, with the unique ID being the directory, and the individual properties of the device files.

There is optional data caching to improved performance, but possible confusion over stale data.

Ds1991

The DS1991 (3) is an iButton with password protected non-volatile memory. Data is read/written with error checking (transparent to the user). The memory is divided into 3 different pages with 3 separate passwords.

Addressing

All 1-wire devices are factory assigned a unique 64-bit address. This address is of the form:
Family Code
8 bits
Address
48 bits
CRC
8 bits

Addressing under OWFS is in hexidecimal, of form:
01.123456789ABC

where 01 is an example 8-bit family code, and 12345678ABC is an example 48 bit address.

The dot is optional, and the CRC code can included. If included, it must be correct.

Datasheet

http://pdfserv.maxim-ic.com/en/ds/DS1991.pdf

See Also

Programs

owfs (1) owhttpd (1) owftpd (1) owserver (1)

Language bindings

owtcl (3) owperl (3)

Clocks

DS1427 (3) DS1904(3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417 (3)

ID

DS2401 (3) DS1990A (3)

Memory

DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3) DS1995 (3) DS1996 (3) DS2431 (3) DS2433 (3) DS2502 (3) DS2506 (3) DS2804 (3)

Switches

DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3)

Temperature

DS1822 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921 (3) DS1821 (3)

Humidity

DS1922 (3)

Voltage

DS2450 (3)

Resistance

DS2890 (3)

Multifunction

DS2436 (3) DS2438 (3) DS2760 (3)

Counter

DS2423 (3)

LCD Screen

LCD (3) DS2408 (3)

Crypto

DS1977 (3)

Availability

http://owfs.sourceforge.net

Author

Christian Magnusson (mag@mag.cx)


Table of Contents

© 2003-4 Paul H. Alfille and The owfs Team
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