R8C-20_1 Datasheet, PDF (92/501 Pages) Renesas Technology Corp – MCU R8C FAMILY / R8C/2x SERIES

R8C/20 Group, R8C/21 Group
10. Clock Generation Circuit
10.4.2.4 Exiting Wait Mode
The MCU exits wait mode by a hardware reset or peripheral function interrupt. When using a hardware reset to
exit wait mode, set the ILVL2 to ILVL0 bits for the peripheral function interrupts to 000b (interrupts disabled)
before executing the WAIT instruction.
The peripheral function interrupts are affected by the CM02 bit. When the CM02 bit is set to 0 (peripheral
function clock does not stop in wait mode), all peripheral function interrupts can be used to exit wait mode.
When the CM02 bit is set to 1 (peripheral function clock stops in wait mode), the peripheral functions using the
peripheral function clock stop operating and the peripheral functions operated by external signals can be used
to exit wait mode.
Table 10.3 lists Interrupts to Exit Wait Mode and Usage Conditions.
Table 10.3 Interrupts to Exit Wait Mode and Usage Conditions
Interrupt
CM02 = 0
Serial Interface Interrupt
Usable when operating with
internal or external clock
Clock Synchronous Serial I/O Usable in all modes
with Chip Select Interrupt /
I²C Bus Interface Interrupt
Key Input Interrupt
Usable
A/D Conversion Interrupt
Usable in one-shot mode
Timer RA Interrupt
Usable in all modes
Timer RB Interrupt
Timer RD Interrupt
Usable in all modes
Usable in all modes
Timer RE Interrupt
INT Interrupt
Usable in all modes
Usable
Voltage Monitor 2 Interrupt
Oscillation Stop Detection
Interrupt
Usable
Usable
CM02 = 1
Usable when operating with external
clock
− (Do not use)
Usable
− (Do not use)
Can be used if there is no filter in event
counter mode.
Usable by selecting fOCO as count
source.
− (Do not use)
Usable by selecting fOCO40M as
count source
− (Do not use)
Usable (INT0 to INT3 can be used if
there is no filter.)
Usable
− (Do not use)
Figure 10.9 shows the Time from Wait Mode to Interrupt Routine Execution.
When using a peripheral function interrupt to exit wait mode, set up the following before executing the WAIT
instruction.
(1) Set the interrupt priority level to the ILVL2 to ILVL0 bits in the interrupt control register of the
peripheral function interrupts to use for exiting wait mode. Set the ILVL2 to ILVL0 bits of the
peripheral function interrupts not to use for exiting wait mode to 000b (disables interrupt).
(2) Set the I flag to 1.
(3) Operate the peripheral function to use for exiting wait mode.
When exiting by a peripheral function interrupt, the time (number of cycles) between interrupt request
generation and interrupt routine execution is determined by the settings of the FMSTP bit in the FMR0 register
as described in Figure 10.9.
The CPU clock, when exiting wait mode by a peripheral function interrupt, is the same clock as the CPU clock
when the WAIT instruction is executed.
Rev.2.00 Aug 27, 2008 Page 76 of 458
REJ09B0250-0200