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M16C/5L Group, M16C/56 Group
9.3.3
Wait Mode
The CPU clock stops in wait mode, therefore, the CPU and the watchdog timer 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. fOCO40M, fOCO-F, 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 2 reset, watchdog timer reset, NMI 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 9.6 lists Pin Status in Wait Mode.
Table 9.6
Pin Status in Wait Mode
Pin
I/O ports
When fC is
selected
CLKOUT
When f1, f8, f32
are selected
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
Maintains the pin state immediately before entering wait mode
Continues to output the clock
•
When the CM02 bit is 0 (peripheral clock, f1, does not stop in wait mode):
Continues to output the clock
•
When the CM02 bit is 1 (peripheral clock, f1, stops in wait mode):
Maintains the pin state immediately before entering wait mode
Pin State
9. Power Control
Page 129 of 803
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