79
5.5
Interrupt Response Time
Table 5.5 shows the interrupt response time, which is the time from the occurrence of an interrupt
request until interrupt exception handling starts and fetching of the first instruction of the interrupt
handling routine begins. Figure 5.4 shows the pipeline when an IRQ interrupt is accepted.
Table 5.5
Interrupt Response Time
Number of States
Item
NMI or On-Chip
Interrupt
IRQ
Notes
Interrupt priority decision
and comparison with SR
mask bit
2
3
Wait for completion of
sequence currently being
executed by CPU
X (
≥
0)
The longest sequence is the
interrupt or address error
exception handling
sequence: X = 4 + m1 + m2
+ m3 + m4. If an interrupt-
masking instruction follows,
however, the time may be
longer.
Time from interrupt
exception handling
(saving PC and SR and
fetching vector address)
until fetching of first
instruction of interrupt
handling routine starts
5 + m1 + m2 + m3
Interrupt
Total
7 + m1 + m2 + m3
8 + m1 + m2 + m3
response
Minimum
10
11
0.50–0.55 µs at 20 MHz
Maximum
11 + 2(m1 + m2 +
m3) + m4
12 + 2(m1 + m2 +
m3) + m4
(m1 = m2 = m3 = m4 = 1)
0.90–0.95 µs at 20 MHz
Notes: m1–m4 are the number of states needed for the following memory accesses:
m1: SR save cycle (longword write)
m2: PC save cycle (longword write)
m3: Vector address read cycle (longword read)
m4: Fetch start instruction of interrupt handling routine
Summary of Contents for HD6417032
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Page 525: ...490 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 18 Self Refresh ...
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