2008-2016 Microchip Technology Inc. DS20002122D-page 17
11AA02E48/11AA02E64
7.0 PRE-PROGRAMMED EUI-48
™
OR EUI-64
™
NODE ADDRESS
The 11AA02EXX is programmed at the factory with a
globally unique node address stored in the upper 1/4 of
the array and write-protected through the STATUS
register. The remaining 1,536 bits are available for
application use.
FIGURE 7-1: MEMORY ORGANIZATION
7.1 Factory-Programmed Write
Protection
In order to help guard against accidental corruption of
the node address, the BP1 and BP0 bits of the STATUS
register are programmed at the factory to ‘0’ and ‘1’,
respectively, as shown in the following table
.
This protects the upper 1/4 of the array (0xC0 to 0xFF)
from write operations. This array block can be utilized
for writing by clearing the BP bits with a Write Status
Register (WRSR) instruction. Note that if this is
performed, care must be taken to prevent overwriting
the node address value.
7.2 EUI-48
™
Node Address
(11AA02E48)
The 6-byte EUI-48
™
node address value of the
11AA02E48 is stored in array locations 0xFA through
0xFF, as shown in Figure 7-2. 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.
7.2.1 EUI-64
™
SUPPORT USING THE
11AA02E48
The pre-programmed EUI-48 node address of the
11AA02E48 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 7-2: EUI-48 NODE ADDRESS PHYSICAL MEMORY MAP EXAMPLE (11AA02E48)
7654 3 2 1 0
XXXX BP1 BP0 WEL WIP
———— 01——
00h
C0h
FFh
Write-Protected
Node Address Block
Standard
EEPROM
Note: Currently, Microchip’s OUIs are
0x0004A3, 0x001EC0, 0xD88039 and
0x5410EC, though this will change as
addresses are exhausted.
Note: As an alternative, the 11AA02E64
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 7.3 “EUI-64™ Node Address
(11AA02E64)” 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
