DS2431: 1024-Bit, 1-Wire EEPROM

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Figure 5. Memory Map

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

1)

R/(W)

Protection Control Byte

Page 0

55h: Write Protect P0; AAh: EPROM mode

P0; 55h or AAh: Write Protect 80h

0081h

1)

R/(W)

Protection Control Byte

Page 1

55h: Write Protect P1; AAh: EPROM mode

P1; 55h or AAh: Write Protect 81h

0082h

1)

R/(W)

Protection Control Byte

Page 2

55h: Write Protect P2; AAh: EPROM mode

P2; 55h or AAh: Write Protect 82h

0083h

1)

R/(W)

Protection Control Byte

Page 3

55h: Write Protect P3; AAh: EPROM mode

P3; 55h or AAh: Write Protect 83h

0084h

1)

R/(W)

Copy Protection Byte

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

N/A

Reserved

write-protect the address nor activate any function.

MEMORY

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 4 memory pages (32 bytes each). These 4 pages are the primary data memory.

Each page can be individually 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 two user

byte/manufacture ID bytes. The manufacturer ID can be a customer-supplied identification code that assists the

application software in identifying the product the DS2431 is associated with. Contact the factory to set up and

register a custom manufacturer ID. The last row is reserved for future use. It is undefined in terms of R/W

functionality and should not be used.

In addition to the main EEPROM array, an 8-byte volatile scratchpad is included. Writes to the EEPROM array are

a two-step process. First, data is written to the scratchpad, and then copied into the main array. This allows the

user to first verify the data written to scratchpad prior to copying into the main array. The device only supports full

row (8-byte) copy operations. In order for data in the scratchpad to be valid for a copy operation, the address

supplied with a Write Scratchpad must start on a row boundary, and 8 full bytes must be written into the

scratchpad.