
INTERRUPTS
KS57C2308/P2308/C2316/P2316
7-6
Multi-Level Interrupt Handling
With multi-level interrupt handling, a lower-priority interrupt request can be executed by manipulating the
interrupt status flags, IS0 and IS1 while a high-priority interrupt is being serviced (see Table 7-2).
When an interrupt is requested during normal program execution, interrupt status flags IS0 and IS1 are set to "1"
and "0", respectively. This setting allows only highest-priority interrupts to be serviced. When a high-priority
request is accepted, both interrupt status flags are then cleared to "0" by software so that a request of any priority
level can be serviced. In this way, the high- and low-priority requests can be serviced in parallel (see Figure 7-4).
Table 7-2. IS1 and IS0 Bit Manipulation for Multi-Level Interrupt Handling
Process Status
Before INT
Effect of Isx Bit Setting
After INT ACK
IS1
IS0
IS1
IS0
0
0
0
All interrupt requests are serviced.
0
1
1
0
1
Only high-priority interrupts as determined by the
current settings in the IPR register are serviced.
1
0
2
1
0
No additional interrupt requests will be serviced.
–
–
–
1
1
Value undefined
–
–
INT Disable
SET IPR
INT Enable
Low or High
Level
Interrupt
Generated
Normal Program
Processing
(Status 0)
Low or High
Level Interrupt
Generated
Single
Interrupt
2-Level
Interrupt
Status 1
INT Enable
Modify Status
High-Level
Interrupt
Generated
3-Level
Interrupt
Status 0
Status 2
INT Disable
Status 0
Status 1
Figure 7-4. Multi-Level Interrupt Handling
Summary of Contents for C2316
Page 30: ...ADDRESS SPACES KS57C2308 P2308 C2316 P2316 2 22 NOTES ...
Page 168: ...SAM47 INSTRUCTION SET KS57C2308 P2308 C2316 P2316 5 94 NOTES ...
Page 170: ......
Page 206: ...POWER DOWN KS57C2308 P2308 C2316 P2316 8 8 NOTES ...
Page 210: ...RESET KS57C2308 P2308 C2316 P2316 9 4 NOTES ...
Page 222: ...I O PORTS KS57C2308 P2308 C2316 P2316 10 12 NOTES ...
Page 272: ...LCD CONTROLLER DRIVER KS57C2308 P2308 C2316 P2316 12 24 NOTES ...
Page 280: ...SERIAL I O INTERFACE KS57C2308 P2308 C2316 P2316 13 8 NOTES ...
Page 294: ...MECHANICAL DATA KS57C2308 P2308 C2316 P2316 15 2 NOTES ...
Page 310: ...KS57P2308 P2316 OTP KS57C2308 P2308 C2316 P2316 16 16 NOTES ...
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