iButton DESCRIPTION
The DS1982 1Kb Add-Only iButton is a rugged read/write data carrier that identifies and stores relevant information about the product or person to which it is attached. This information can be accessed with minimal hardware, for example, a single port pin of a microcontroller. The DS1982 consists of a factory lasered registration number that includes a unique 48-bit serial number, an 8-bit CRC, and an 8-bit Family Code (09h) plus 1Kb of EPROM that is user-programmable. The power to program and read the DS1982 is derived entirely from the 1-Wire communication line. Data is transferred serially via the 1-Wire protocol that requires only a single data lead and a ground return. The entire device can be programmed and then write-protected if desired. Alternatively, the part may be programmed multiple times with new data being appended to, but not overwriting, existing data with each subsequent programming of the device.

SPECIAL FEATURES
■ 1024 bits Electrically Programmable Read Only Memory (EPROM) communicates with the economy of one signal plus ground
■ EPROM partitioned into four 256-bit pages for randomly accessing packetized data
■ Each memory page can be permanently write protected to prevent tampering
■ Device is an “add only” memory where additional data can be programmed into EPROM without disturbing existing data
■ Architecture allows software to patch data by superseding an old page in favor of a newly programmed page
■ Reduces control, address, data, power, and programming signals to a single data pin
■ 8-bit family code specifies DS1982 communications requirements to reader
■ Reads over a wide voltage range of 2.8V to 6.0V from -40°C to +85°C; programs at 11.5V to 12.0V from -40°C to +50°C

COMMON iButton FEATURES
■ Unique, factory-lasered and tested 64-bit registration number (8-bit family code + 48-bit serial number + 8-bit CRC tester) assures absolute traceability because no two parts are alike
■ Multidrop controller for MicroLAN
■ Digital identification and information by momentary contact
■ Chip-based data carrier compactly stores information
■ Data can be accessed while affixed to object
■ Economically communicates to bus master with a single digital signal at 16.3kbps
■ Standard 16mm diameter and 1-Wire® protocol ensure compatibility with iButton® family
■ Button shape is self-aligning with cup-shaped probes
■ Durable stainless steel case engraved with registration number withstands harsh environments
■ Easily affixed with self-stick adhesive backing, latched by its flange, or locked with a ring pressed onto its rim
■ Presence detector acknowledges when reader first applies voltage