DS1994L-F5 데이터 시트보기 (PDF) - Dallas Semiconductor -> Maxim Integrated
부품명
상세내역
제조사
DS1994L-F5 Datasheet PDF : 22 Pages
| |||
EXAMPLES OF ACCESSORIES
DS9096P Self-Stick Adhesive Pad
DS9101 Multi-Purpose Clip
DS9093RA Mounting Lock Ring
DS9093F Snap-In Fob
DS9092 iButton Probe
DS1994
iButton DESCRIPTION
The DS1994 Memory iButton is a rugged read/write data carrier that acts as a localized database, easily
accessible with minimal hardware. The nonvolatile memory and optional timekeeping capability offer a
simple solution to storing and retrieving vital information pertaining to the object to which the iButton is
attached. Data is transferred serially through the 1-Wire protocol that 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
transfers the data to memory. This process ensures data integrity when modifying the memory. A 48-bit
serial number is factory lasered into each DS1994 to provide a guaranteed unique identity that 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 DS1994 to be easily used by human operators. Accessories permit the DS1994 to be
mounted on almost any surface including plastic key fobs, photo-ID badges, and PC boards.
The DS1994 also includes time-keeping functions, a real-time clock/calendar, interval timer, cycle
counter, and programmable interrupts, in addition to the nonvolatile memory. The internal clock can be
programmed to deny memory access based on absolute time/date, total elapsed time, or the number of
accesses. These features allow the DS1994 to be used to create a stopwatch, alarm clock, time and date
stamp, logbook, hour meter, calendar, system power cycle timer, interval timer, and event scheduler.
OPERATION
The DS1994 has four main data components: 1) 64-bit lasered ROM, 2) 256-bit scratchpad, 3) 4096-bit
SRAM, and 4) timekeeping registers. The timekeeping section utilizes an on-chip oscillator that is
connected to a 32.768kHz crystal. The SRAM and time-keeping registers reside in one contiguous
address space referred to hereafter as memory. All data is read and written least significant bit first.
The memory functions are not available until the ROM function protocol has been established. This
protocol is described in the ROM functions flowchart (Figure 9). The master must first provide one of
four ROM function commands: 1) read ROM, 2) match ROM, 3) search ROM, or 4) skip ROM. After a
ROM function sequence has been successfully executed, the memory functions are accessible and the
master can then provide any one of the four memory function commands (Figure 6).
2 of 22
Share Link: 