11AA02UID
7.1
Manufacturer and Device Codes
7.0
PREPROGRAMMED UNIQUE
32-BIT SERIAL NUMBER
In addition to the serial number, a manufacturer code is
stored at location 0xFA and a device identifier is stored
at 0xFB. The manufacturer code is fixed as 0x29. For
the 11AA02UID, the device identifier is ‘0x11’. The first
‘1’ indicates the UNI/O® bus family and the second ‘1’
indicates a 2 Kbit memory density.
The 11AA02UID is programmed at the factory with a
unique 32-bit serial number 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.
Note:
The 32-bit serial number is unique across
all Microchip UID-family serial EEPROM
devices.
7.2
Factory-Programmed Write
Protection
In order to help guard against accidental corruption of
the serial number, 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:
FIGURE 7-1:
MEMORY ORGANIZATION
00h
7
6
5
4
3
BP1
0
2
BP0
1
1
0
Standard
EEPROM
X
X
X
X
WEL
—
WIP
—
—
—
—
—
C0h
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 serial number.
Write-Protected
Serial Number Block
FFh
The 4-byte serial number is stored in array locations
0xFC through 0xFF, as shown in Figure 7-2.
FIGURE 7-2:
SERIAL NUMBER PHYSICAL MEMORY MAP EXAMPLE
Manufacturer
Code
Device
Code
Description
32-bit Serial Number
29h
11h
12h
34h
56h
78h
FFh
Data
Type
Fixed
Serialized
Array
Address
FAh
FBh
FCh
FDh
FEh
TABLE 7-1:
EXTENDED READ EXAMPLES
7.3
Extending the 32-bit Serial
Number
Serial Number
End Address
Start Address
Length
For applications that require serial numbers larger than
32 bits, additional data bytes can be used to pad the
provided serial number to meet the required length.
Any data byte values can be used for padding as the
32-bit serial number ensures the extended serial
number remains unique.
0xFC
0xFA
0xF8
0xF0
0xE0
0xFF
0xFF
0xFF
0xFF
0xFF
32 bits
48 bits
64 bits
128 bits
256 bits
The padding can be performed in two ways. The first
method is to pad the data in software by combining the
32-bit serial number from the 11AA02UID with fixed
data. The second method is to extend the number of
bytes read from the 11AA02UID to meet the required
length. Table 7-1 shows example address ranges and
their corresponding serial number lengths.
2013 Microchip Technology Inc.
DS20005206A-page 17
MICROCHIP [ MICROCHIP ]
