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9. Interrupts
M16C/28 Group
Under development Preliminary specification
Specifications in this manual are tentative and subject to change.
Rev.0.60 2004.02.01
page 64 of N
REJ09B0047-0060Z
Interrupt sources
7
Level that is set to IPL
_______
Watchdog timer, NMI, Oscillation stop and re-oscillation detection,
voltage down detection
_________
Software, address match, DBC, single-step
Not changed
9.4.2 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 9.4.2.1 is set in the IPL. Shown in Table 9.4.2.1 are the IPL values of software and
special interrupts when they are accepted.
Table 9.4.2.1. IPL Level That is Set to IPL When A Software or Special Interrupt Is Accepted
Instruction
Interrupt sequence
Instruction in
interrupt routine
Time
Interrupt response time
(a)
(b)
Interrupt request acknowledged
Interrupt request generated
(a) The 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) The 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.
Interrupt vector address
Even
Odd
SP value
Even
Odd
Even
Odd
Without wait
18 cycles
19 cycles
20 cycles
Figure 9.4.1.1. Interrupt response time
9.4.1 Interrupt Response Time
Figure 9.4.1.1 shows the interrupt response time. The interrupt response or interrupt acknowledge
time denotes time from when an interrupt request is generated till when the first instruction in the
interrupt routine is executed. Specifically, it consists of the time from when an interrupt request is
generated till when the instruction then executing is completed ((a) in Figure 9.4.1.1) and the time
during which the interrupt sequence is executed ((b) in Figure 9.4.1.1).