DS1427 [DALLAS]
Time iButton; iButton的时间
| 型号： | DS1427 |
| 厂家： | 
DALLAS SEMICONDUCTOR |
| 描述： | Time iButton |
| 文件： | 总2页 (文件大小：23K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DS1427
DS1427
Time iButton
FEATURES
PACKAGE OUTLINE
• Provides a unique 64–bit serial number, 4K bits of
RAM
• No external power required
TM
• Uses inexpensive 1–Wire protocol
• Universally portable across platforms
• Programmable secure real time clock with alarm and
elapsed timer.
16mm
DESCRIPTION
Authorization iButtons are sophisticated microelectron-
ics,sealedintominiaturestainlesssteelcans,creatinga
low cost, portable medium for storing and controlling
access to sensitive information.
tem provides easy to use commands which are
embedded into the application in order to utilize the
iButton resources during run time.
Each Dallas iButton is uniquely serialized with a 64–bit
code that is laser–etched in the silicon. This unique ID
providesabasiclevelofsecurity,istraceableinthefield,
and makes it possible to identify the specific iButton in a
field of many.
iButtons are used with port adapters as a hardware
based protection system for software. iButtons help
protect the right to copy software by actually protecting
the right to execute it. Software can now be locked to a
user, a machine, or an application with a complete audit
trail and guaranteed uniqueness.
The serial number is divided into three parts (see Figure
1). The 8–bit family code tells the Access System (and
consequently the developer) what type of iButton is
being used. The next 48 bits are lasered sequentially
with no two numbers the same. The last 8 bits contain a
Cyclic Redundancy Check (CRC) value that has been
calculated across the family code and the 48–bit serial
number. The CRC ensures that iButtoncommunication
is error free.
The DS1427 provides a 64–bit unique ID number, 4K
bits of RAM, and a programmable real time clock. The
DS1427 is used in leasing and rental applications, soft-
waremetering, andtovaryvalidprotectionkeysbytime.
Ability to distribute demonstration software that expire
on a date controlled by the deliverer.
Hardware communication with the iButtons is con-
ducted via a 1–wire interface. The conversion from a
PC I/O port to the 1–wire interface is the responsibility of
the port adapter.
The DS1427 tracks elapsed time from either initial pro-
gramming or from first access by the application soft-
ware. All timers and alarms can be locked from repro-
gramming, so that the time base is not compromised in
any way.
Software applications communicate with the iButton
using Dallas’ Access System, which is contained in any
of the port adapter Developer’s kits. The Access Sys-
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DS1427
Memory is organized into 16 pages of 256 bits each. An
additional scratch page is provided to validate data
before it is written into storage areas.
The real time clock keeps time in 1/256 second incre-
ments. This can be translated into seconds, minutes,
days, months or years. A read of the clock will return the
number of seconds after the reference date. The
elapsed timer can be stopped or started based on the
contents of the configuration registers.
There are four function commands to address the
memory. Three commands are used to read, write, or
copy data to or from the scratch page and the storage
areasaccordingly. All data is written to the scratch page
first, verified, andthencopiedtotheappropriatestorage
locations. The fourth command is used to read the con-
tents of the storage locations, the clock, elapsed timer,
alarm registers, or the configuration/status registers.
The configuration and status registers control the oper-
ating mode of the DS1427. Setting alarms and control-
ling interrupts for the clock and elapsed timer are user
selectable. Additional registers are used to control the
clock oscillator, elapsed timer triggers, and to provide
write protection for various memory locations.
DS1427 TIME iButton ORGANIZATION Figure 1
FAMILY CODE
10000100
8-BIT CRC CODE
MSB
48-BIT SERIAL NUMBER
512 Bytes NV SRAM
16 Pages
32 Bytes per Page
0000h
01FFh
0200h
0201h
Configuration and Status Registers
0202h
0206h
0207h
020Bh
020Ch
020Fh
0210h
0214h
0215h
0219h
021Ah
021Dh
Real Time Clock
Elapsed Timer
Reserved
RTC Alarm
Elapsed Time Alarm
Reserved
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