DS2502-E64 Maxim, DS2502-E64 Datasheet - Page 2

• Manufacturer Part Number: DS2502-E64
• Description: The DS2502-E64 is a variant of the DS2502 1024-bit Add-Only Memory
• Manufacturer: Maxim

The first 32 bytes of the DS2502-E64’s EPROM memory contain a globally unique 64-bit node address
(EUI-64) and are write-protected. The data structure follows the conventions of UniqueWare devices
using Default Data Structure (Figure 1). This format is also known as UDP (universal data packet) and is
commonly used in 1-Wire APIs. Therefore, if using one of those APIs one can call a high level function
to read and verify the inverted CRC16. The UDP is defined in Application Note 114,
Structure, and the APIs can be found in the
Figure 1. EUI-64 NODE ADDRESS CHIP DATA STRUCTURE
The data record starts with a length byte (0Ch) and the 4-byte UniqueWare Project ID 00001128h. The
next eight bytes contain the EUI-64 global identifier (node address) which consists of an incrementing
40-bit extension identifier and the IEEE-assigned 24-bit company ID value 006035h. An inverted 16-bit
CRC ends the data record. The remaining bytes of the 32-byte memory page remain unprogrammed.
Neither the 40–bit extension identifier nor the 24-bit company ID are related to the 64-bit ROM
registration number. The ROM registration number is used to provide a unique address to access the
DS2502-E64 when multidropped on a 1-Wire bus.
EXAMPLE
Assume that a manufacturer’s company ID value is 006035h and the 40-bit extension identifier is
234567ABCDh. The EUI-64 value generated from these two numbers is 006035234567ABCDh, whose
byte and bit representations are illustrated in Figure 2.
Figure 2. SAMPLE EUI-64 VALUE
This information is stored in the DS2502-E64 as 64-bit number with the least significant byte at the lower
address. Including the length byte and the inverted CRC, the complete set of data is shown in Figure 3.
Figure 3. PHYSICAL ADDRESS AND DATA MAPPING INSIDE THE DEVICE
HIGH ADDRESS
MOST SIGNIFICANTBYTE
MOST SIGNIFICANT BIT
ADDRESS
DATA
0000 0000
(UNUSED)
17 BYTES
FFh
00
0110 0000
MSB
2 BYTES
CRC16
0E
60
3E
LSB
0D
FF
0011 0101
MSB
COMPANY ID VALUE
3 BYTES CONSTANT
35
0C
00
006035h
0B
60
0010 0011
0A
35
23
LSB
1-Wire Software Development
09
23
MSB
0100 0101
2 of 4
5 BYTES SERIALIZATION
EXTENSION ID VALUE
08
45
45
07
67
0110 0111
AB
06
67
LSB
CD
05
MSB
1010 1011
LEAST SIGNIFICANTBYTE
Kits.
04
00
4 BYTES CONSTANT
LEAST SIGNIFICANT BIT
AB
PROJECT ID
00001128h
03
00
02
11
1100 1101
CD
LSB
01
28
LOW ADDRESS
1-Wire File
DS2502-E64
0C
00
HEX
BINARY
LENGTH
1 BYTE
0Ch