R8C/13 Group
10.1 Interrupt Overview
• Interrupt Response Time
Figure 10.5 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 inter-
rupt routine is executed. Specifically, it consists of a time from when an interrupt request is gener-
ated till when the instruction then executing is completed (see #a in Figure 10.5) and a time during
which the interrupt sequence is executed (20 cycles, see #b in Figure 10.5).
Interrupt request generated
Interrupt request acknowledged
Time
Instruction in
interrupt routine
Instruction
(a)
Interrupt sequence
20 cycles (b)
Interrupt response time
(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) 21 cycles for address match and single-step interrupts.
Figure 10.5 Interrupt Response Time
• 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 10.5 is set in the IPL. Shown in Table 10.5 are the IPL values of software and special
interrupts when they are accepted.
Table 10.5 IPL Level That Is Set to IPL When A Software or Special Interrupt Is Accepted
Interrupt factors
Level that is set to IPL
Watchdog timer, oscillation stop detection, voltage detection
Software, address match, single-step
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Rev.1.20 Jan 27, 2006 page 56 of 205
REJ09B0111-0120
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