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011800
SPECIAL FEATURES
65536 bits Electrically Programmable Read
Only Memory (EPROM) communicates with
the economy of one signal plus ground
Overdrive mode boosts communication
speed to 142 kbits per second
EPROM partitioned into two hundred and 56
256-bit pages for randomly accessing
packetized data records
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 DS1986
communications requirements to reader
Reads over a wide voltage range of 2.8V to
6.0V from -40C to +85C; programs at
11.5V to 12.0V from -40C to +85C
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 16.3 kbits per
second
Standard 16 mm 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
Meets UL#913 (4th Edit.); Intrinsically Safe
Apparatus, Approved under Entity Concept
for use in Class I, Division 1, Group A, B, C
and D Locations (application pending)
F3 MICROCAN
F5 MICROCAN
DATA
GROUND
0.36
0.51
3.10
c 1993
YYWW REGISTERED RR
19
OF
000000FBC52B
16.25
17.35
5.89
DATA
GROUND
0.36
0.51
c 1993
YYWW REGISTERED RR
99
0F
000000FBD8B3
16.25
17.35
All dimensions shown in millimeters.
DS1986
64-kbits Add-Only iButton
TM
www.iButton.com
DS1986
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ORDERING INFORMATION
DS1986-F3 F3
MicroCan
DS1986-F5 F5
MicroCan
EXAMPLES OF ACCESSORIES
DS9096P
Self-Stick Adhesive Pad
DS9101 Multi-Purpose
Clip
DS9093RA Mounting
Lock
Ring
DS9093F Snap-In
Fob
DS9092 iButton
Probe
iButton DESCRIPTION
The DS1986 64-kbit 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 DS1986 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 (0Fh) plus 64 kbit of EPROM which is user-programmable. The power to program and
read the DS1986 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 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 DS1986 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 DS1986 to be used easily
by human operators or automatic equipment. Accessories permit the DS1986 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 DS1986. The DS1986 has three main data components: 1) 64-bit lasered ROM, 2) 65536 bits
EPROM Data Memory, and 3) 2816 bits EPROM Status Memory. 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 DS1986 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 six ROM Function Commands, 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM, 5)
Overdrive-Skip ROM, or 6) Overdrive-Match ROM. Upon completion of an Overdrive ROM command
byte executed at regular speed, the device will enter the Overdrive mode where all subsequent
communication occurs at a higher speed. 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
DS1986
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Function Commands is described in Figure 8. After a ROM Function Command is successfully executed,
the memory functions that operate on the EPROM portions of the DS1986 become accessible and the bus
master may issue any one of the five Memory Function Commands specific to the DS1986 to read or
program the various data fields. The protocol for these Memory Function Commands is described in
Figure 5. All data is read and written least significant bit first.
64-BIT LASERED ROM
Each DS1986 contains a unique ROM code that is 64 bits long. The first eight bits are a 1-Wire family
code. The next 48 bits are a unique serial number. The last eight bits are a CRC of the first 56 bits. (See
Figure 3.) The 64-bit ROM and ROM Function Control section allow the DS1986 to operate as a 1-Wire
device and follow the 1-Wire protocol detailed in the section "1-Wire Bus System". The memory
functions required to read and program the EPROM sections of the DS1986 are not accessible until the
ROM function protocol has been satisfied. This protocol is described in the ROM functions flow chart
(Figure 8). The 1-Wire bus master must first provide one of six ROM function commands: 1) Read ROM,
2) Match ROM, 3) Search ROM, or 4) Skip ROM, 5) Overdrive-Skip ROM, or 6) Overdrive-Match
ROM. After a ROM function sequence has been successfully executed, the bus master may then provide
any one of the memory function commands specific to the DS1986 (Figure 5).
The 1-Wire CRC of the lasered ROM is generated using the polynomial X
8
+ X
5
+ X
4
+ 1. Additional
information about the Dallas Semiconductor 1-Wire Cyclic Redundancy Check is available in the Book
of DS19xx iButton Standards. The shift register acting as the CRC accumulator is initialized to zero.
Then starting with the least significant bit of the family code, one bit at a time is shifted in. After the
eighth bit of the family code has been entered, then the serial number is entered. After the 48th bit of the
serial number has been entered, the shift register contains the CRC value. Shifting in the eight bits of
CRC should return the shift register to all zeroes.
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