Wait Mode - Renesas M16C/64A Series User Manual

M16C/64A Group
9.3.3

Wait Mode

The CPU clock stops in wait mode, therefore, the CPU, the watchdog timer, and NMI / SD digital filter
clocked by the CPU clock stops running. However, if the CSPRO bit in the CSPR register is 1 (count
source protection mode enabled), the watchdog timer remains active. Because the clock generator
does not stop, peripheral functions supplied by a peripheral clock keep operating.
9.3.3.1 Peripheral Function Clock Stop Function
When the CM02 bit is 1 (peripheral function clock f1 stops in wait mode), the f1 clock is turned off
while in wait mode, and power consumption is reduced. However, all the peripheral clocks except f1
(i.e. fOCO-S, fC, and fC32) do not stop.
9.3.3.2 Entering Wait Mode
The MCU enters wait mode by executing a WAIT instruction.
When the CM11 bit is 1 (PLL clock selected as CPU clock source), set the CM11 bit to 0 (main clock
selected as CPU clock source) before entering wait mode. Chip power consumption can be reduced
by setting the PLC07 bit to 0 (PLL off).
When using wait mode, set the following:
(1) Set the I flag to 0.
(2) Set the interrupt priority level of bits ILVL2 to ILVL0 in the interrupt control register for the
peripheral function interrupt which is used to exit wait mode. Start the peripheral function which
is used to exit wait mode if it is stopped.
(3) Set 000b (interrupt disabled) to bits ILVL2 to ILVL0 in the interrupt control registers for the
peripheral function interrupts not used to exit wait mode.
(When using any of the following resets or interrupts to exit wait mode, set 000b to bits ILVL2 to
ILVL0 in all interrupt control registers for peripheral function interrupts: hardware reset, voltage
monitor 0 reset, voltage monitor 1 reset, voltage monitor 2 reset, watchdog timer reset, NMI
interrupt, voltage monitor 1 interrupt, or voltage monitor 2 interrupt).
(4) Set the I flag to 1.
(5) Execute the WAIT instruction.
9.3.3.3 Pin Status in Wait Mode
Table 9.5 lists Pin Status in Wait Mode.
Table 9.5 Pin Status in Wait Mode
Pin
A0 to A19, D0 to D15,
CS0 to CS3 , BHE
RD , WR , WRL , WRH
HLDA , BCLK
ALE
I/O ports
fC selected
CLKOUT
f1, f8, f32
selected
R01UH0136EJ0210 Rev.2.10
Jul 31, 2012
Memory Expansion Mode
Microprocessor Mode
Retains the status just prior to
entering wait mode
High
High
Low
Retains the status just prior to
entering wait mode
Cannot be used as a CLKOUT
pin
Single-Chip Mode
Cannot be used as a bus control pin
Retains the status just prior to entering

wait mode

Does not stop
Does not stop when the CM02 bit is 0.
When the CM02 bit is 1, the status
immediately prior to entering wait
mode is retained.
9. Power Control
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