DS2432X 查看數據表（PDF） - Dallas Semiconductor -> Maxim Integrated

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DS2432X

1k-Bit Protected 1-Wire™ EEPROM with SHA-1 Engine

Dallas Semiconductor -> Maxim Integrated 

PRELIMINARY

DS2432

64-BIT LASERED ROM

Each DS2432 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 1-Wire CRC is generated using a polynomial generator consisting of a shift register and

XOR gates as shown in Figure 4. The polynomial is X8 + X5 + X4 + 1. Additional information about the

Dallas 1-Wire Cyclic Redundancy Check is available in the Book of DS19xx iButton Standards from

Dallas Semiconductor. The shift register bits are initialized to zero. Then starting with the least significant

bit of the family code, one bit at a time is shifted in. After the 8th 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 zeros.

HIERARCHCAL STRUCTURE FOR 1-WIRE PROTOCOL Figure 2

BUS

Master

1-Wire net

Other

Devices

Command

Level:

1-Wire ROM Function

Commands (see Figure 9)

DS2432-specific

Memory Function

Commands (see Figure 7)

DS2432

Available

Commands:

Read ROM

Match ROM

Search ROM

Skip ROM

Resume

Overdrive Skip

Overdrive Match

Data Field

Affected:

64-bit Reg. #, RC-Flag

64-bit Reg. #, RC-Flag

64-bit Reg. #, RC-Flag

RC-Flag

RC-Flag

64-bit Reg. #, RC-Flag, OD-Flag

64-bit Reg. #, RC-Flag, OD-Flag

Write Scratchpad

Read Scratchpad

Load First Secret

Compute Next Secret

Copy Scratchpad

Read Authenti-

cated Page

Read Memory

64-bit Scratchpad, Flags

64-bit Scratchpad

Secret, Flags

Secret, Data Memory, Scratchpad

Data Memory or Register Page,

Secret, Flags, 64-Bit Reg. #,

Data Memory, Secret, 64-bit Reg. #,

3-Byte Challenge in Scratchpad

Data Memory, Register Page, Reg. #

64-BIT LASERED ROM Figure 3

MSB

8-Bit CRC Code

48-Bit Serial Number

MSB

LSB MSB

LSB

8-Bit Family Code (33h)

LSB MSB

LSB

3 of 30

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