1024-Bit, 1-Wire EEPROM

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7

Memory Access

Data memory and registers are located in a linear

address space, as shown in Figure 5. The data memory

and the registers have unrestricted read access. The

DS2431 EEPROM array consists of 18 rows of 8 bytes

each. The first 16 rows are divided equally into four

memory pages (32 bytes each). These four pages are

the primary data memory. Each page can be individu-

ally set to open (unprotected), write protected, or

EPROM mode by setting the associated protection byte

in the register row. The last two rows contain protection

registers and reserved bytes. The register row consists

of 4 protection control bytes, a copy-protection byte,

the factory byte, and 2 user byte/manufacture ID bytes.

The manufacturer ID can be a customer-supplied iden-

tification code that assists the application software in

identifying the product the DS2431 is associated with.

1ST

STAGE

2ND

STAGE

3RD

STAGE

4TH

STAGE

7TH

STAGE

8TH

STAGE

6TH

STAGE

5TH

STAGE

INPUT DATA

Figure 4. 1-Wire CRC Generator

ADDRESS RANGE

TYPE

DESCRIPTION

PROTECTION CODES

0000h to 001Fh

R/(W)

Data Memory Page 0

—

0020h to 003Fh

R/(W)

Data Memory Page 1

—

0040h to 005Fh

R/(W)

Data Memory Page 2

—

0060h to 007Fh

R/(W)

Data Memory Page 3

—

0080h*

R/(W)

Protection Control Byte Page 0

55h: Write Protect P0; AAh: EPROM Mode P0;

55h or AAh: Write Protect 80h

0081h*

R/(W)

Protection Control Byte Page 1

55h: Write Protect P1; AAh: EPROM Mode P1;

55h or AAh: Write Protect 81h

0082h*

R/(W)

Protection Control Byte Page 2

55h: Write Protect P2; AAh: EPROM Mode P2;

55h or AAh: Write Protect 82h

0083h*

R/(W)

Protection Control Byte Page 3

55h: Write Protect P3; AAh: EPROM Mode P3;

55h or AAh: Write Protect 83h

0084h*

R/(W)

Copy Protection Byte

55h or AAh: Copy Protect 0080h:008Fh, and Any

Write-Protected Pages

0085h

R

Factory Byte. Set at Factory.

AAh: Write Protect 85h, 86h, 87h;

55h: Write Protect 85h; Unprotect 86h, 87h

0086h

R/(W)

User Byte/Manufacturer ID

—

0087h

R/(W)

User Byte/Manufacturer ID

—

0088h to 008Fh

—

Reserved

—

Figure 5. Memory Map

*

Once programmed to AAh or 55h this address becomes read only. All other codes can be stored, but neither write protect the

address nor activate any function.