19-4891 Rev 8/09 DS1982 1Kb Add-Only iButton SPECIAL FEATURES COMMON iButton FEATURES 1024 bits Electrically Programmable Read- Unique, factory-lasered and tested 64-bit Only Memory (EPROM) communicates with registration number (8-bit family code + 48-bit the economy of one signal plus ground serial number + 8-bit CRC tester) assures EPROM partitioned into four 256-bit pages for absolute traceability because no two parts are randomly accessing packetized data alike Each memory page can be permanently write- Multidrop controller for MicroLAN protected to prevent tampering Digital identification and information by Device is an add only memory where momentary contact additional data can be programmed into Chip-based data carrier compactly stores EPROM without disturbing existing data information Architecture allows software to patch data by Data can be accessed while affixed to object superseding an old page in favor of a newly Economically communicates to bus master programmed page with a single digital signal at 16.3kbps Reduces control, address, data, power, and Standard 16mm diameter and 1-Wire protocol programming signals to a single data pin ensure compatibility with iButton family 8-bit family code specifies DS1982 Button shape is self-aligning with cup-shaped communications requirements to reader probes Reads over a wide voltage range of 2.8V to Durable stainless steel case engraved with 6.0V from -40C to +85C programs at 11.5V registration number withstands harsh to 12.0V from -40C to +50C environments Easily affixed with self-stick adhesive backing, ORDERING INFORMATION latched by its flange, or locked with a ring DS1982-F3+ F3 MicroCan pressed onto its rim DS1982-F5+ F5 MicroCan Presence detector acknowledges when reader +Denotes a lead(Pb)-free/RoHS-compliant product. first applies voltage EXAMPLES OF ACCESSORIES iButton and 1-Wire are registered trademarks of Maxim Integrated Products, Inc. DS9096P Self-Stick Adhesive Pad DS9101 Multi-Purpose Clip DS9093RA Mounting Lock Ring DS9093F Snap-In Fob DS9092 iButton Probe F3 MicroCan F5 MicroCan Page 1 of 24 DS1982 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. Note: Individual bits can be changed only from a logical 1 to a logical 0, never from a logical 0 to a logical 1. A provision is also included for indicating that a certain page or pages of data are no longer valid and have been replaced with new or updated data that is now residing at an alternate page address. This page address redirection allows software to patch data and enhance the flexibility of the device as a standalone database. The 48-bit serial number that is factory-lasered into each DS1982 provides a guaranteed unique identity that 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 DS1982 to be used easily by human operators or automatic equipment. Accessories permit the DS1982 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, storage of calibration constants, and debit tokens. OVERVIEW The block diagram in Figure 1 shows the relationships between the major control and memory sections of the DS1982. The DS1982 has three main data components: 1) 64-bit lasered ROM, 2) 1024-bit EPROM, and 3) EPROM Status Bytes. The device derives its power for read operations entirely from the 1-Wire communication line by storing energy on an internal capacitor during periods of time when the signal line is high and continues to operate off of this parasite power source during the low times of the 1-Wire line until it returns high to replenish the parasite (capacitor) supply. During programming, 1-Wire communication occurs at normal voltage levels and then is pulsed momentarily to the programming voltage to cause the selected EPROM bits to be programmed. The 1-Wire line must be able to provide 12 volts and 10 milliamperes to adequately program the EPROM portions of the part. Whenever programming voltages are present on the 1-Wire line a special high voltage detect circuit within the DS1982 generates an internal logic signal to indicate this condition. The hierarchical structure of the 1- Wire protocol is shown in Figure 2. The bus master must first provide one of the four ROM function commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM. These commands operate on the 64-bit lasered ROM portion of each device and can singulate a specific device if many are present on the 1-Wire line as well as indicate to the bus master how many and what types of devices are present. The protocol required for these ROM function commands is described in Figure 9. After a ROM function command is successfully executed, the memory functions that operate on the EPROM portions of the DS1982 become accessible and the bus master may issue any one of the five memory function commands specific to the DS1982 to read or program the various data fields. The protocol for these memory function commands is described in Figure 6. All data is read and written least significant bit first. Page 2 of 24