Datasheet

MCP79410/MCP79411/MCP79412
DS20002266E-page 22  2010-2013 Microchip Technology Inc.
8.2 Unique ID
The MCP7941X features an additional 64-bit unique ID
area. This is separate and in addition to the 1K of on-
board EEPROM.
The unique ID is located at addresses 0xF0 through
0xF7 using the EEPROM I
2
C address. Reading the
unique ID requires the user to simply address these
bytes.The unique ID is factory programmed on devices
to provide a unique IEEE EUI-48 or EUI-64 value. In
addition, customer-provided codes can also be
programmed. Please contact your Microchip sales
channel for more information on custom programming.
The unique ID locations are always readable.
The format of the unique ID is shown in Figure 8-2. This
is an example and the OUI may change.
FIGURE 8-2: EUI-48/64 NODE ADDRESS PHYSICAL MEMORY MAP EXAMPLE
The unique ID area is protected to prevent unintended
writes to these locations. The unlock sequence is
detailed in 8.2.1 “Unlock Sequence” and consists of
the following sequence:
• A single write of 0x55 to RTCC Addr. 0x09. Stop
• A single write of 0xAA to RTCC Addr. 0x09. Stop
A Stop condition must be used to terminate a I
2
C
sequence, a Restart will not complete the sequence.
F2h F7h
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:
00-04-A3-12-34-56-78-9A
FFhFFh
Unused
F1hF0h
F7h
24-bit Organizationally
Unique Identifier
40-bit Extension
Identifier
A3h 12h 34h 56h 78h 9Ah
Description
Data
Array
Address
04h00h
F0h
F3h
F4h
F5h
F6h