Datasheet

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 individually set to open
(unprotected), write protected, or EPROM mode by set-
ting the associated protection byte in the register row. As
a factory default, the entire data memory is unprotected
and its contents are undefined. 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
identification code that assists the application software
in identifying the product the DS2431 is associated with.
Figure 4. 1-Wire CRC Generator
Figure 5. Memory Map
1ST
STAGE
2ND
STAGE
3RD
STAGE
4TH
STAGE
7TH
STAGE
8TH
STAGE
6TH
STAGE
5TH
STAGE
X
0
X
1
X
2
X
3
X
4
POLYNOMIAL = X
8
+ X
5
+ X
4
+ 1
INPUT DATA
X
5
X
6
X
7
X
8
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 —
*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.
DS2431 1024-Bit, 1-Wire EEPROM
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