Register 64: System Handler Control and State (SYSHNDCTRL), offset 0xD24
Note:
This register can only be accessed from privileged mode.
The
SYSHNDCTRL
register enables the system handlers, and indicates the pending status of the
usage fault, bus fault, memory management fault, and SVC exceptions as well as the active status
of the system handlers.
If a system handler is disabled and the corresponding fault occurs, the processor treats the fault as
a hard fault.
This register can be modified to change the pending or active status of system exceptions. An OS
kernel can write to the active bits to perform a context switch that changes the current exception
type.
Caution – Software that changes the value of an active bit in this register without correct adjustment
to the stacked content can cause the processor to generate a fault exception. Ensure software that writes
to this register retains and subsequently restores the current active status.
If the value of a bit in this register must be modified after enabling the system handlers, a
read-modify-write procedure must be used to ensure that only the required bit is modified.
System Handler Control and State (SYSHNDCTRL)
Base 0xE000.E000
Offset 0xD24
Type RW, reset 0x0000.0000
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
MEM
BUS
USAGE
reserved
RW
RW
RW
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
Type
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
MEMA
BUSA
reserved
USGA
reserved
SVCA
MON
reserved
PNDSV
TICK
USAGEP
MEMP
BUSP
SVC
RW
RW
RO
RW
RO
RO
RO
RW
RW
RO
RW
RW
RW
RW
RW
RW
Type
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset
Description
Reset
Type
Name
Bit/Field
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0x000
RO
reserved
31:19
Usage Fault Enable
Description
Value
Disables the usage fault exception.
0
Enables the usage fault exception.
1
0
RW
USAGE
18
Bus Fault Enable
Description
Value
Disables the bus fault exception.
0
Enables the bus fault exception.
1
0
RW
BUS
17
June 18, 2014
180
Texas Instruments-Production Data
Cortex-M4 Peripherals