NEC Network Controller uPD98502 User Manual
Page 184
CHAPTER 2 V
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4120A
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Preliminary User’s Manual S15543EJ1V0UM
2.8.5.2 Masking interrupt signals
Figure 2-89 shows the masking of the CPU core interrupt signals.
Cause register bits 15 to 8 (IP7 to IP0) are AND-ORed with Status register interrupt mask bits 15 to 8 (IM7 to
IM0) to mask individual interrupts.
Status register bit 0 is a global Interrupt Enable (IE). It is ANDed with the output of the AND-OR logic shown
in Figure 2-89 to produce the CPU core interrupt signal. The EXL bit in the Status register also enables
these interrupts.
Figure 2-89. Masking of Interrupt Request Signals
Timer interrupt
IM0
IE
Software interrutpts
generated in CPU core
Status register
SR0
IM1
IM2
IM3
IM4
IM5
IM6
IM7
IP0
IP1
IP2
IP3
IP4
IP5
IP6
IP7
Ordinary
interrupts
Status register
SR (15:8)
Cause register
(15:8)
8
AND-OR block
AND block
1
1
CPU core interrupt
8
8
9
10
11
12
13
14
15
8
9
10
11
12
13
14
15
Bit
Function
Setting
IE
Whole interrupts enable
1 : Enable
0 : Disable
IM(7:0)
Interrupt mask
Each bit
1 : Enable
0 : Disable
IP(7:0)
Interrupt request
Each bit
1 : Pending
0 : Not pending