Ubuntu Manpage: DS1977 - Password Protected 32kbit Memory iButton

NAME

       DS1977 - Password Protected 32kbit Memory iButton

SYNOPSIS

       Non-volatile memory.

       37   [.]XXXXXXXXXXXX[XX][/[   memory   |   pages/page.[0-510|ALL]   |   set_number/full  |
       set_number/read  |  set_password/enabled  |  set_password/full   |   set_password/read   |
       use_number/full | use_number/read | use_password/full | use_password/read | address | crc8
       | id | locator | r_address | r_id | r_locator | type ]]

FAMILY CODE

       37 DS1977

SPECIAL PROPERTIES

memory
read-write, binary
32704 bytes of memory. Possibly protected by a password.

pages/page.0 ... pages/page.510 pages/page.ALL
read-write, binary
Memory is split into 511 pages of 64 bytes each. ALL is an aggregate of the pages. Each
page is accessed sequentially.

set_number/full set_number/read
write-only, ascii
Passwords entered as numbers, either decimal, or hex of form 0x0123456789ABCDEF. Handled
the same as set_password/xxx

set_password/enable
read-write, yes-no
Turn on/off password protection for the DS1977, or return the current state.

set_password/full set_password/read
write-only, binary
Passwords (8 byte values) that allow read or full access to the DS1977 memory. The
password set by set_password/xxx are stored in the DS1977 and locally in the program as
well (as if use_password/xxx was also called).

use_password/full use_password/read
write-only, binary
Passwords (8 byte values) that allow read or full access to the DS1977 memory. The
password set by

use_number/full use_number/read
write-only, ascii
Passwords entered as numbers, either decimal, or hex of form 0x0123456789ABCDEF. Handled
the same as use_password/xxx

use_password/full use_password/read
write-only, binary
Passwords (8 byte values) that allow read or full access to the DS1977 memory. The
password set by use_password/xxx are stored in the program and must match the passwords
stored in the DS1977. Changing the DS1977 passwords using set_password/xxx will change
these values as well. use_password/xxx are stored in the program and must match the
passwords stored in the DS1977. Changing the DS1977 passwords using set_password/xxx will
change these values as well.

STANDARD PROPERTIES

address
r_address
read-only, ascii
The entire 64-bit unique ID. Given as upper case hexadecimal 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 hexadecimal digits (0-9A-
F).

family
read-only, ascii
The 8-bit family code. Unique to each type of device. Given as upper case hexadecimal
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 hexadecimal 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 hexadecimal) 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 principle 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.

DS1977
The DS1977 (3) is an iButton with static memory that is optionally protected by a
password.

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 hexadecimal, 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/DS1977.pdf

AVAILABILITY

       http://www.owfs.org

AUTHOR

       Paul Alfille (paul.alfille@gmail.com)