Region 1
Disabled subregion
Disabled subregion
Region 2, with
subregions
Base address of both regions
Offset from
base address
0
64KB
128KB
192KB
256KB
320KB
384KB
448KB
512KB
Functional Description
1604
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
Cortex-M3 Peripherals
25.2.4.1.4 Example of SRD Use
Two regions with the same base address overlap. Region one is 128 KB, and region two is 512 KB. To
ensure the attributes from region one apply to the first 128 KB region, configure the SRD field for region
two to 0x03 to disable the first two subregions, as
shows.
Figure 25-1. SRD Use Example
25.2.4.2 MPU Access Permission Attributes
The access permission bits, TEX, S, C, B, AP, and XN of the MPUATTR register, control access to the
corresponding memory region. If an access is made to an area of memory without the required
permissions, then the MPU generates a permission fault.
shows the encodings for the TEX, C, B, and S access permission bits. All encodings are
shown for completeness, however the current implementation of the Cortex-M3 does not support the
concept of cacheability or shareability. Refer to
for information on programming the
MPU for Concerto implementations.
(1)
The MPU ignores the value of this bit.
Table 25-3. TEX, S, C, and B Bit Field Encoding
TEX
S
C
B
Memory Type
Shareability
Other Attributes
000b
x
(1)
0
0
Strongly Ordered
Shareable
-
000
x
(1)
0
1
Device
Shareable
-
000
0
1
0
Normal
Not shareable
Outer and inner
write-through. No
write allocate.
000
1
1
0
Normal
Shareable
000
0
1
1
Normal
Not shareable
000
1
1
1
Normal
Shareable
001
0
0
0
Normal
Not shareable
Outer and inner
non-cacheable.
001
1
0
0
Normal
Shareable
001
x
(1)
0
1
Reserved encoding
-
-
001
x
(1)
1
0
Reserved encoding
-
-
001
0
1
1
Normal
Not shareable
Outer and inner
write-back. Write
and read allocate.
001
1
1
1
Normal
Shareable
010
x
(1)
0
0
Device
Not shareable
Non-shared
device.
010
x
(1)
0
1
Reserved encoding
-
-
010
x
(1)
1
x
(1)
Reserved encoding
-
-