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M16C/62P Group (M16C/62P, M16C/62PT)
24.4 Power Control
• When exiting stop mode by hardware reset, set RESET pin to "L" until a main clock oscillation is stabilized.
• Set the MR0 bit in the TAiMR register (i=0 to 4) to "0" (pulse is not output) to use the timer A to exit stop
mode.
• Insert more than four NOP instructions after an WAIT instruction or a instruction to set the CM10 bit of
CM1 register to "1". When shifting to wait mode or stop mode, an instruction queue reads ahead to the
next instruction to halt a program by an WAIT instruction and an instruction to set the CM10 bit to "1" (all
clocks stopped). The next instruction may be executed before entering wait mode or stop mode, depend-
ing on a combination of instruction and an execution timing.
• Wait the main clock oscillation stabilizes, before switching the clock source for CPU clock to the main
clock.
Similarly, wait until the sub clock oscillates stably before switching the clock source for CPU clock to the
sub clock.
• Suggestions to reduce power consumption
Ports
The processor retains the state of each I/O port even when it goes to wait mode or to stop mode. A
current flows in active I/O ports. A pass current flows in input ports that high-impedance state. When
entering wait mode or stop mode, set non-used ports to input and stabilize the potential.
A/D converter
When A/D conversion is not performed, set the VCUT bit of ADiCON1 register to "0" (no VREF con-
nection). When A/D conversion is performed, start the A/D conversion at least 1 µs or longer after
setting the VCUT bit to "1" (VREF connection).
D/A converter
When not performing D/A conversion, set the DAiE bit (i=0, 1) of DACON register to "0" (input inhib-
ited) and DAi register to "00h".
Stopping peripheral functions
Use the CM0 register CM02 bit to stop the unnecessary peripheral functions during wait mode.
However, because the peripheral function clock (fC32) generated from the sub-clock does not stop,
this measure is not conducive to reducing the power consumption of the chip. If low speed mode or
low power dissipation mode is to be changed to wait mode, set the CM02 bit to "0" (do not peripheral
function clock stopped when in wait mode), before changing wait mode.
Switching the oscillation-driving capacity
Set the driving capacity to "LOW" when oscillation is stable.
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page 329
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24. Usage Precaution
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