DS1961S

5 of 36

Figure 4. 1-WIRE CRC GENERATOR

X

0

X

1

X

2

X

3

X

4

X

5

X

6

X

7

X

8

Polynomial = X

1st

STAGE

2nd

STAGE

3rd

STAGE

4th

STAGE

6th

STAGE

5th

STAGE

7th

STAGE

8th

STAGE

INPUT DATA

MEMORY MAP

The DS1961S has four memory areas: data memory, secrets memory, register page with special function

registers and user-bytes, and a scratchpad. The data memory is organized in pages of 32 bytes. Secret,

register page, and scratchpad are 8 bytes each. The scratchpad acts as a buffer when writing to the data

memory, loading the initial secret or when writing to the register page.

Data memory, secrets memory, and the register page are located in a linear address space, as shown in

Figure 5. The data memory and the register page have unrestricted read access. Writing to the data

memory and the register page requires knowledge of the secret.

Figure 5. DS1961S MEMORY MAP

ADDRESS RANGE

DESCRIPTION

NOTE

0000h to 001Fh

Data Memory Page 0

No Write-Access Without Secret

0020h to 003Fh

Data Memory Page 1

No Write-Access Without Secret

0040h to 005Fh

Data Memory Page 2

No Write-Access Without Secret

0060h to 007Fh

Data Memory Page 3

No Write-Access Without Secret

0080h to 0087h

Secrets Memory

No Read Access; No Secret Needed for

Write Access

0088h

1)

Write-Protect Secret, 008Ch to 008Fh

Protection Activated by Code AAh or 55h

0089h

1)

Write-Protect Pages 0 to 3

Protection Activated by Code AAh or 55h

008Ah

1)

User Byte, Self-Protecting

Protection Activated by Code AAh or 55h

008Bh

Factory Byte (Read Only)

Reads Either AAh or 55h; See Text

008Ch

1)

User Byte/EPROM Mode Control for

Page 1

Mode Activated by Code AAh or 55h

008Dh

1)

User Byte/Write-Protect Page 0 Only

Protection Activated by Code AAh or 55h

008Eh to 008Fh

User Bytes/Manufacturer ID

Function Depends on Factory Byte

0090h to 0097h

64-Bit Identity Register

Read-Only Access

will neither write-protect the address nor activate any function.