Ubuntu Manpage: DS1991 - 1152bit MultiKey iButton

Provided by: owfs-doc_2.8p15-1ubuntu4_all

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 |  r_address  |  r_id  |
       r_locator | type ]]

FAMILY CODE

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 pages/page.2 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 pages/password.2 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 pages/ident.2 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 settings/page.2 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 settings/ident.2 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 settings/password.2 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 settings/reset_password.2
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 settings/change_password.2
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
preceding 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 (DEPRECATED)
read-only, yes-no
Is the device currently present on the 1-wire bus?

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
Semiconductor, Inc. The bus is a low-power low-speed low-connector scheme where the data
line can also provide power.

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

The 1-wire scheme uses a single bus master and multiple slaves on the same wire. The bus
master initiates all communication. The slaves can be individually discovered and
addressed using their unique ID.

Bus masters come in a variety of configurations including serial, parallel, i2c, network
or USB adapters.

OWFS design
OWFS is a suite of programs that designed to 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 are represented as simple
files that can be read and written.

Details of the individual slave or master design are hidden behind a consistent interface.
The goal is to provide an easy set of tools for a software designer to create monitoring
or control applications. There are some performance enhancements in the implementation,
including data caching, parallel access to bus masters, and aggregation of device
communication. Still the fundemental goal has been ease of use, flexibility and
correctness rather than speed.

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

AVAILABILITY

       http://www.owfs.org

AUTHOR

       Christian Magnusson (mag@mag.cx)