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Rev.1.10 Jul 01, 2005 page 69 of 318
REJ09B0124-0110
M16C/6N Group (M16C/6NK, M16C/6NM) 9. Interrupt
Under development
This document is under development and its contents are subject to change.
Figure 9.6 Interrupt response time
9.5.6 Variation of IPL when Interrupt Request is Accepted
When a maskable interrupt request is accepted, the interrupt priority level of the accepted interrupt is set
in the IPL.
When a software interrupt or special interrupt request is accepted, one of the interrupt priority levels listed
in Table 9.5 is set in the IPL. Table 9.5 shows the IPL values of software and special interrupts when they
are accepted.
Table 9.5 IPL Level that is Set to IPL When A Software or Special Interrupt is Accepted
9.5.5 Interrupt Response Time
Figure 9.6 shows the interrupt response time. The interrupt response or interrupt acknowledge time
denotes a time from when an interrupt request is generated till when the first instruction in the interrupt
routine is executed. Specifically, it consists of a time from when an interrupt request is generated till when
the instruction then executing is completed ((a) on Figure 9.6) and a time during which the interrupt
sequence is executed ((b) on Figure 9.6).
Interrupt Sources Value that is Set to IPL
_______
Oscillation Stop and Re-oscillation Detection, Watchdog Timer, NMI
_________
Software, Address Match, DBC, Single-Step
Interrupt Vector Address SP Value 16-bit Bus, without Wait 8-bit Bus, without Wait
Even
Odd
Even
Odd
Even
Odd
18 cycles
19 cycles
19 cycles
20 cycles
20 cycles
Instruction Interrupt sequence
Instruction in
interrupt routine
Time
Interrupt response time
(a) (b)
Interrupt request acknowledgedInterrupt request generated
(a) A time from when an interrupt request is generated till when the instruction then
executing is completed. The length of this time varies with the instruction being
executed. The DIVX instruction requires the longest time, which is equal to 30 cycles
(without wait state, the divisor being a register).
(b) A time during which the interrupt sequence is executed. For details, see the table
below. Note, however, that the values in this table must be increased 2 cycles for the
DBC interrupt and 1 cycle for the address match and single-step interrupts.
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