R8C29 Datasheet, PDF (98/471 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MCU R8C FAMILY / R8C/2x SERIES

R8C/28 Group, R8C/29 Group
10. Clock Generation Circuit
Handling procedure of internal power
low consumption enabled by VCA20 bit
Step (1)
Enter low-speed clock mode or low-speed on-
chip oscillator mode
Step (2)
Stop XIN clock and high-speed on-chip
oscillator clock
Step (3)
VCA20 ← 1 (internal power low consumption
enabled)^{(2, 3)}
Step (4)
Enter wait mode⁽⁴⁾
Exit wait mode by
interrupt
(Note 1)
In interrupt handling routine
Step (5)
VCA20 ← 0 (internal power low consumption
disabled)⁽²⁾
Step (6)
Start XIN clock or high-speed on-chip
oscillator clock
Step (7) (Wait until XIN clock oscillation stabilizes)
Step (8)
Enter mode other than low-speed clock mode
or low-speed on-chip oscillator mode
If it is necessary to start
the high-speed clock or
the high-speed on-chip
oscillator in the interrupt
handling routine, execute
steps (5) to (7) in the
interrupt routine.
Step (5)
VCA20 ← 0 (internal power low consumption
disabled)⁽²⁾
Step (6)
Start XIN clock or high-speed on-chip
oscillator clock
Step (7) (Wait until XIN clock oscillation stabilizes)
Step (8)
Enter high-speed clock mode or
high-speed on-chip oscillator mode
Interrupt handling
Step (1)
Enter low-speed clock mode or
low-speed on-chip oscillator mode
Step (2)
Stop XIN clock and high-speed on-chip
oscillator clock
Step (3)
VCA20 ← 1 (internal power low consumption
enabled)^{(2, 3)}
If the high-speed clock or
high-speed on-chip
oscillator is started in the
interrupt handling routine,
execute steps (1) to (3) at
the last of the interrupt
routine.
Interrupt handling completed
NOTES:
1. Execute this handling to all interrupt handlings generated around the WAIT instruction. If it is not necessary to start the high-speed
clock or the high-speed on-chip oscillator in the interrupt handling, it does not need to be started.
2. Do not set the VCA20 bit to 0 with the instruction immediately after setting the VCA20 bit to 1. Also, do not do the opposite.
3. When the VCA20 bit is set to 1, do not set the CM10 bit to 1 (stop mode).
4. When entering wait mode, follow 10.7.2 Wait Mode.
VCA20: Bit in VCA2 register
Figure 10.10 Procedure for Enabling Reduced Internal Power Consumption Using VCA20 bit
Rev.2.10 Sep 26, 2008 Page 81 of 441
REJ09B0279-0210