24AA02E48/24AA025E48/24AA02E64/24AA025E64
DS20002124G-page 14 2008-2016 Microchip Technology Inc.
9.0 PRE-PROGRAMMED EUI-48™
OR EUI-64™ NODE ADDRESS
The 24AA02XEXX is programmed at the factory with a
globally unique node address stored in the upper half
of the array and permanently write-protected. The
remaining 1,024 bits are available for application use.
FIGURE 9-1: MEMORY ORGANIZATION
9.1 EUI-48™ Node Address
(24AAXXXE48)
The 6-byte EUI-48™ node address value of the
24AAXXXE48 is stored in array locations 0xFA through
0xFF, as shown in Figure 9-2. The first three bytes are
the Organizationally Unique Identifier (OUI) assigned
to Microchip by the IEEE Registration Authority. The
remaining three bytes are the Extension Identifier, and
are generated by Microchip to ensure a globally
unique, 48-bit value.
9.1.1 EUI-64™ SUPPORT USING THE
24AAXXXE48
The pre-programmed EUI-48 node address of the
24AAXXXE48 can easily be encapsulated at the
application level to form a globally unique, 64-bit node
address for systems utilizing the EUI-64 standard. This
is done by adding 0xFFFE between the OUI and the
Extension Identifier, as shown below.
FIGURE 9-2: EUI-48 NODE ADDRESS PHYSICAL MEMORY MAP EXAMPLE (24AAXXXE48)
Note: Currently, Microchip’s OUIs are
0x0004A3, 0X001EC0, 0xD88039 and
0x5410EC, though this will change as
addresses are exhausted.
00h
80h
FFh
Write-Protected
Node Address Block
Standard
EEPROM
Note: As an alternative, the 24AAXXXE64
features an EUI-64 node address that can
be used in EUI-64 applications directly
without the need for encapsulation,
thereby simplifying system software. See
Section 9.2 “EUI-64™ Node Address
(24AAXXXE64)” for details.
FAh FFh
24-bit Organizationally
Unique Identifier
24-bit Extension
Identifier
00h 04h A3h 12h 34h 56h
Corresponding EUI-48™ Node Address:
00-04-A3-12-34-56
Description
Data
Array
Address
Corresponding EUI-64™ Node Address After Encapsulation:
00-04-A3-FF-FE-12-34-56
