DS1991(3)

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] | ]]

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 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

ALARMS
None.

DESCRIPTION

  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

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

SEE ALSO

AVAILABILITY
http://www.owfs.org

AUTHOR
Christian Magnusson (mag@mag.cx)