CHAPTER 5 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User’s Manual U13850EJ4V0UM
154
5.7 Interrupt Latency Time
The following table describes the interrupt latency time (from interrupt request generation to start of interrupt
servicing).
Figure 5-22. Pipeline Operation at Interrupt Request Acknowledgement
System clock
IF
ID
IFX IDX
IFX
EX MEM
INT1 INT2 INT3
IF
ID
EX MEM WB
INT4
WB
Interrupt request
Instruction 1
Instruction 2
Instruction 3
Interrupt acknowledge operation
Instruction (start instruction of
interrupt servicing routine)
7 to 14 system clocks
4 system clocks
INT1 to INT4: Interrupt acknowledge processing
IF
X
:
Invalid instruction fetch
ID
X
:
Invalid instruction decode
Interrupt Latency Time (system clock)
Internal interrupt
External interrupt
Condition
Minimum
11
13
Maximum
18
20
Time to eliminate noise (2 system clocks) is also necessary
for external interrupts, except when:
•
In IDLE/STOP mode
•
External bus is accessed
•
Two or more interrupt request non-sample instructions
are executed in succession
•
Access to interrupt control register
5.8 Periods Where Interrupt Is Not Acknowledged
An interrupt is acknowledged while an instruction is being executed. However, no interrupt will be acknowledged
between interrupt non-sample instruction and next instruction.
Interrupt request non-sample instruction
• EI instruction
• DI instruction
• LDSR reg2, 0x5 instruction (vs. PSW)
(1) Acknowledging interrupt servicing after execution of EI instruction
The V850/SB1 and V850/SB2 require at least seven clocks to identify an interrupt request from when the
interrupt request was generated until it is acknowledged. Because subsequent instructions are executed during
this period, the interrupt is disabled if the DI instruction (which disables interrupts) is executed. As a result, all
the interrupt requests are held pending until the EI instruction (which enables interrupts) is executed again.
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