Control Register File
2-17
CPU Data Paths and Control
SPRU733
2.7.6 Interrupt Enable Register (IER)
The interrupt enable register (IER) enables and disables individual interrupts.
The IER is shown in Figure 2
−
7 and described in Table 2
−
9.
Figure 2
−
7. Interrupt Enable Register (IER)
31
16
Reserved
R-0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
IE15 IE14 IE13 IE12 IE11 IE10
IE9
IE8
IE7
IE6
IE5
IE4
Reserved
NMIE
1
R/W-0
R-0
R/W-0 R-1
Legend:
R = Readable by the
MVC
instruction; W = Writeable by the
MVC
instruction; -
n
= value after reset
Table 2
−
9. Interrupt Enable Register (IER) Field Descriptions
Bit
Field
Value Description
31
−
16 Reserved
0
Reserved. The reserved bit location is always read as 0. A value written to this
field has no effect.
15
−
4
IE
n
Interrupt enable. An interrupt triggers interrupt processing only if the
corresponding bit is set to 1.
0
Interrupt is disabled.
1
Interrupt is enabled.
3
−
2
Reserved
0
Reserved. The reserved bit location is always read as 0. A value written to this
field has no effect.
1
NMIE
Nonmaskable interrupt enable. An interrupt triggers interrupt processing only if
the bit is set to 1.
The NMIE bit is cleared at reset. After reset, you must set the NMIE bit to
enable the NMI and to allow INT15
−
INT4 to be enabled by the GIE bit in CSR
and the corresponding IER bit. You cannot manually clear the NMIE bit; a write
of 0 has no effect. The NMIE bit is also cleared by the occurrence of an NMI.
0
All nonreset interrupts are disabled.
1
All nonreset interrupts are enabled. The NMIE bit is set only by completing a
B NRP
instruction or by a write of 1 to the NMIE bit.
0
1
1
Reset interrupt enable. You cannot disable the reset interrupt.