Wait Mode - Renesas M16C FAMILY Hardware Manual

Under development
Preliminary specification
Specifications in this manual are tentative and subject to change.
R8C/11 Group

6.4.2 Wait Mode

In wait mode, the CPU clock is turned off, so are the CPU and the watchdog timer because both are
operated by the CPU clock. Because the main clock and ring oscillator clock both are on, the periph-
eral functions using these clocks keep operating.
• Peripheral Function Clock Stop Function
If the CM02 bit is "1" (peripheral function clocks turned off during wait mode), the f
f , f , and f
8SIO 32SIO
that much.
• Entering Wait Mode
The microcomputer is placed into wait mode by executing the WAIT instruction.
• Pin Status During Wait Mode
The status before wait mode is retained.
• Exiting Wait Mode
The microcomputer is moved out of 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 "000
The peripheral function interrupts are affected by the CM02 bit. If CM02 bit is "0" (peripheral function
clocks not turned off during wait mode), all peripheral function interrupts can be used to exit wait
mode. If CM02 bit is "1" (peripheral function clocks turned off during wait mode), the peripheral
functions using the peripheral function clocks stop operating, so that only the peripheral functions
clocked by external signals can be used to exit from wait mode.
Table 6. 3 lists the interrupts to exit wait mode and the usage conditions.
When using a peripheral function interrupt to exit wait mode, set up the following before executing
the WAIT instruction.
1. In the ILVL2 to ILVL0 bits in the interrupt control register, set the interrupt priority level of the
peripheral function interrupt to be used to exit wait mode.
Also, for all of the peripheral function interrupts not used to exit wait mode, set the ILVL2 to ILVL0
bits to "000
2. Set the I flag to "1".
3. Enable the peripheral function whose interrupt is to be used to exit wait mode.
In this case, when an interrupt request is generated and the CPU clock is thereby turned on, an
interrupt sequence is executed.
The CPU clock turned on when exiting wait mode by a peripheral function interrupt is the same CPU
clock that was on when the WAIT instruction was executed.
Table 6.3 Interrupts to Exit Wait Mode and Usage Conditions
Interrupt
Serial I/O interrupt
Key input interrupt
A-D conversion interrupt Can be used in one-shot mode
Timer X interrupt
Timer Y interrupt
INT interrupt
Voltage detection interrupt Can be used
Rev.0.91 2003 Sep 08
clocks are turned off when in wait mode, with the power consumption reduced
AD
" (interrupts disabled) before executing the WAIT instruction.
2
" (interrupt disable).
2
CM02=0
Can be used when operating with
internal or external clock
Can be used
Can be used in all modes
Can be used in all modes
Can be used
page 38 of 184
CM02=1
Can be used when operating with
external clock
Can be used
(Do not use)
Can be used in event counter mode
Can be used when counting inputs from
CNTR1 pin in timer mode
Can be used (INT0 and INT3 can be used
if there is no filter.
Can be used
6.4 Power Control
, f , f , f , f ,
1 2 8 32 1SIO