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MPU Registers
170
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Cortex-M4 Peripherals
2.6.2 MPUCTRL Register (Offset = 0xD94) [reset = 0x0]
MPU Control (MPUCTRL), offset 0xD94
NOTE:
This register can only be accessed from privileged mode.
The MPUCTRL register enables the MPU, enables the default memory map background region, and
enables use of the MPU when in the hard fault, Non-maskable Interrupt (NMI), and Fault Mask Register
(FAULTMASK) escalated handlers.
When the ENABLE and PRIVDEFEN bits are both set:
•
For privileged accesses, the default memory map is as described in
. Any access by
privileged software that does not address an enabled memory region behaves as defined by the
default memory map.
•
Any access by unprivileged software that does not address an enabled memory region causes a
memory management fault.
Execute Never (XN) and Strongly Ordered rules always apply to the System Control Space regardless of
the value of the ENABLE bit.
When the ENABLE bit is set, at least one region of the memory map must be enabled for the system to
function unless the PRIVDEFEN bit is set. If the PRIVDEFEN bit is set and no regions are enabled, then
only privileged software can operate.
When the ENABLE bit is clear, the system uses the default memory map, which has the same memory
attributes as if the MPU is not implemented (see
for more information). The default memory
map applies to accesses from both privileged and unprivileged software.
When the MPU is enabled, accesses to the System Control Space and vector table are always permitted.
Other areas are accessible based on regions and whether PRIVDEFEN is set.
Unless HFNMIENA is set, the MPU is not enabled when the processor is executing the handler for an
exception with priority –1 or –2. These priorities are only possible when handling a hard fault or NMI
exception or when FAULTMASK is enabled. Setting the HFNMIENA bit enables the MPU when operating
with these two priorities.
MPUCTRL is shown in
and described in
Return to
Figure 2-29. MPUCTRL Register
31
30
29
28
27
26
25
24
RESERVED
R-0x0
23
22
21
20
19
18
17
16
RESERVED
R-0x0
15
14
13
12
11
10
9
8
RESERVED
R-0x0
7
6
5
4
3
2
1
0
RESERVED
PRIVDEFEN
HFNMIENA
ENABLE
R-0x0
R/W-0x0
R/W-0x0
R/W-0x0