1024-Bit, 1-Wire EEPROM
DS2431
8
5
4
POLYNOMIAL = X + X + X + 1
1ST
2ND
3RD
4TH
5TH
6TH
7TH
8TH
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
0
1
2
3
4
5
6
7
8
X
X
X
X
X
X
X
X
X
INPUT DATA
Figure 4. 1-Wire CRC Generator
EPROM mode by setting the associated protection
byte in the register row. As a factory default, the entire
data memory is unprotected and its contents are unde-
fined. The last two rows contain protection registers
and reserved bytes. The register row consists of 4 pro-
tection control bytes, a copy-protection byte, the facto-
ry byte, and 2 user byte/manufacture ID bytes. The
manufacturer ID can be a customer-supplied identifi-
cation code that assists the application software in
identifying the product the DS2431 is associated with.
Memory Access
Data memory and registers are located in a linear
address space, as shown in Figure 5. The data memo-
ry 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 indi-
vidually set to open (unprotected), write protected, or
ADDRESS RANGE
0000h to 001Fh
0020h to 003Fh
0040h to 005Fh
0060h to 007Fh
TYPE
R/(W)
R/(W)
R/(W)
R/(W)
DESCRIPTION
Data Memory Page 0
Data Memory Page 1
Data Memory Page 2
Data Memory Page 3
PROTECTION CODES
—
—
—
—
55h: Write Protect P0; AAh: EPROM Mode P0;
55h or AAh: Write Protect 80h
0080h*
0081h*
0082h*
0083h*
0084h*
0085h
R/(W)
R/(W)
R/(W)
R/(W)
R/(W)
R
Protection Control Byte Page 0
Protection Control Byte Page 1
Protection Control Byte Page 2
Protection Control Byte Page 3
Copy Protection Byte
55h: Write Protect P1; AAh: EPROM Mode P1;
55h or AAh: Write Protect 81h
55h: Write Protect P2; AAh: EPROM Mode P2;
55h or AAh: Write Protect 82h
55h: Write Protect P3; AAh: EPROM Mode P3;
55h or AAh: Write Protect 83h
55h or AAh: Copy Protect 0080h:008Fh, and Any
Write-Protected Pages
AAh: Write Protect 85h, 86h, 87h;
55h: Write Protect 85h; Unprotect 86h, 87h
Factory Byte. Set at Factory.
0086h
0087h
R/(W)
R/(W)
—
User Byte/Manufacturer ID
User Byte/Manufacturer ID
Reserved
—
—
—
0088h to 008Fh
*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.
Figure 5. Memory Map
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7
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
