RX610 Group
2. CPU
R01UH0032EJ0120 Rev.1.20
Page 87 of 1006
Feb 20, 2013
2.8.4
Numbers of Cycles for Response to Interrupts
Table 2.15 lists numbers of cycles taken by processing for response to interrupts.
Table 2.15 Numbers of Cycles for Response to Interrupts
Type of Interrupt Request/Details of Processing
Fast Interrupt
Other Interrupts
ICU
Judgment of priority order
2 cycles
2 cycles
CPU
Number of cycles from notification to acceptance of the
interrupt request
N cycles (varies with the instruction being executed at the time the
interrupt was received)
CPU—Pre-processing by hardware
Saving the current PC and PSW values in RAM (or in control
registers in the case of the fast interrupt)
Reading of the vector
Branching to the start of the interrupt Exception handling
routine
4 cycles
6 cycles
Times calculated from the values in table 2.15 will be applicable when access to memory from the CPU is always
processed with no waiting. The on-chip RAM and ROM in products of the RX62N/RX621 Groups always allows such
access. Numbers of cycles for response to interrupts can be minimized by placing program code (and vectors) in on-chip
ROM and the stack in on-chip RAM. Furthermore, place the addresses where handlers start on eight-byte boundaries.
For information on the number of cycles from notification to acceptance of the interrupt request, indicated by N in the
table above, see tables 2.13, Instructions that are Converted into a Single Micro-Operation, and 2.14, Instructions that are
Converted into Multiple Micro-Operations.
The timing of interrupt acceptance depends on the state of the CPU's pipelines. For more information on this, see section
9.3.1, Timing of Acceptance and Saved PC Values.