LM3S2276 Datasheet, PDF (283/785 Pages) Texas Instruments – Stellaris® LM3S2276 Microcontroller

Stellaris® LM3S2276 Microcontroller
Register 18: Flash Memory Protection Read Enable 3 (FMPRE3), offset 0x20C
Note: Offset is relative to System Control base address of 0x400FE000.
This register stores the read-only protection bits for each 2-KB flash block (FMPPEn stores the
execute-only bits). Flash memory up to a total of 64 KB is controlled by this register. Other FMPREn
registers (if any) provide protection for other 64K blocks. This register is loaded during the power-on
reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for
all implemented banks. This achieves a policy of open access and programmability. The register
bits may be changed by writing the specific register bit. However, this register is R/W0; the user can
only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are
not permanent until the register is committed (saved), at which point the bit change is permanent.
If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on
reset sequence. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. If the
Flash memory size on the device is less than 192 KB, this register usually reads as zeroes, but
software should not rely on these bits to be zero. For additional information, see the "Flash Memory
Protection" section.
Flash Memory Protection Read Enable 3 (FMPRE3)
Base 0x400F.E000
Offset 0x20C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
READ_ENABLE
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
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
READ_ENABLE
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
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit/Field
31:0
Name
READ_ENABLE
Type
Reset Description
R/W 0x00000000 Flash Read Enable
Configures 2-KB flash blocks to be read only. The policies may be
combined as shown in the table “Flash Protection Policy Combinations”.
Value
Description
0x00000000 Bits [31:0] each enable protection on a 2-KB block of
Flash memory in the range from 193 to 256 KB.
November 17, 2011
283
Texas Instruments-Production Data