LM3S8938 Datasheet, PDF (148/550 Pages) List of Unclassifed Manufacturers – Microcontroller

Internal Memory
Register 12: User Register 1 (USER_REG1), offset 0x1E4
Note: Offset is relative to System Control base address of 0x400FE000.
This register provides 31 bits of user-defined data that is non-volatile and can only be written once.
Bit 31 indicates that the register is available to be written and is controlled through hardware to
ensure that the register is only written once. The write-once characteristics of this register are useful
for keeping static information like communication addresses that need to be unique per part and
would otherwise require an external EEPROM or other non-volatile device.
User Register 1 (USER_REG1)
Base 0x400F.E000
Offset 0x1E4
Type R/W, reset 0x8FFF.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
NOTWRITTEN
DATA
Type R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
1
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
DATA
Type R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Bit/Field
31
30:0
Name
NOTWRITTEN
DATA
Type
Reset Description
R/W
1
Specifies that this 32-bit dword has not been written.
R/W 0xFFFFFFF Contains the user data value. This field is initialized to all 1s and can
only be written once.
148
June 14, 2007
Luminary Micro Confidential-Advance Product Information