DS1971

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iButton DESCRIPTION

The DS1971 256-bit EEPROM 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 DS1971 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 (14H) plus 256 bits of EEPROM. The power to program and read the DS1971 is

derived entirely from the 1-Wire communication line. Data is transferred serially via the 1-Wire protocol

which requires only a single data lead and a ground return. The 48-bit serial number that is factory-

lasered into each DS1971 provides a guaranteed unique identity which allows for absolute traceability.

The durable MicroCan package is highly resistant to harsh environments such as dirt, moisture, and

shock. Its compact button-shaped profile is self-aligning with cup-shaped receptacles, allowing the

DS1971 to be used easily by human operators or automatic equipment. Accessories permit the DS1971 to

be mounted on printed circuit boards, plastic key fobs, photo-ID badges, ID bracelets, and many other

objects. Applications include work-in-progress tracking, electronic travelers, access control and storage of

calibration constants.

OVERVIEW

The block diagram in Figure 1 shows the relationships between the major control and memory sections of

the DS1971. The DS1971 has four main data components: 1) 64-bit lasered ROM, 2) 256-bit EEPROM

data memory with scratchpad, 3) 64-bit one-time programmable application register with scratchpad, and

4) 8-bit status memory. The bus master must first provide one of the ROM Function Commands before

the memory functions become accessible. All data is read and written least significant bit first.

The DS1971 contains the same memory chip as the DS2430A. For a full description of the logical

behavior, please refer to the DS2430A data sheet.