DS1963L

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iButton DESCRIPTION

The DS1963L Monetary iButton is a rugged read/write data carrier that acts as a localized database that

can be easily accessed with minimal hardware. The nonvolatile memory offers a simple solution to

storing and retrieving information pertaining to the object to which the iButton is associated. Data is

transferred serially via the 1-Wire protocol which requires only a single data lead and a ground return.

The scratchpad is an additional page that acts as a buffer when writing to memory. Data is first written

to the scratchpad where it can be read back. After the data has been verified, a copy scratchpad

command will transfer the data to memory. This process ensures data integrity when modifying the

memory. A 48-bit serial number is factory lasered into each DS1963L to provide a guaranteed unique

identity which allows for absolute traceability. The durable MicroCan package is highly resistant to

environmental hazards such as dirt, moisture, and shock. Its compact coin-shaped profile is self-aligning

with mating receptacles, allowing the DS1963L to be easily used by human operators. Accessories

permit the DS1963L to be mounted on almost any surface including plastic key fobs, photo-ID badges

and printed circuit boards.

APPLICATION

The DS1963L Monetary iButton can store encrypted data which represents money. The unique

registration number, the page write cycle counters, CRC generator and tamper-detect bits prevent

unauthorized refilling of the purses. Four independent change purses can be randomly accessed from

the on-chip directory. Tamper-detect bits report if the purses have experienced physical tampering. Each

write cycle (“Monetary Transaction”) generates a unique number to audit the dispensing and refilling of

the purses. A change purse can be decremented with less than 100 ms touch dwell time for rapid

processing in crowded public facilities.

OVERVIEW

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

the DS1963L. The DS1963L has four main data components: 1) 64-bit lasered ROM, 2) 256-bit

scratchpad, 3) 4096-bit SRAM, and 4) four 32-bit read-only page write cycle counters. The hierarchical

structure of the 1-Wire protocol is shown in Figure 2. Each of these counters is associated with one of the

256-bit memory pages. The four counters of the DS1963L are associated with pages 12 to 15. The

contents of the counter are read together with the memory data using a special command. 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 standard speed, the device will enter Overdrive mode where

all subsequent communication occurs at a higher speed. The protocol required for these ROM function

commands is described in Figure 9. After a ROM function command is successfully executed, the

memory functions become accessible and the master may provide any one of the five memory function

commands. The protocol for these memory function commands is described in Figure 7. All data is read

and written least significant bit first.