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M16C/62P Group (M16C/62P, M16C/62PT)
10.4.1.7 On-chip Oscillator Low Power Dissipation Mode
The main clock is turned off after being placed in on-chip oscillator mode. The CPU clock can be
selected as in the on-chip oscillator mode. The on-chip oscillator clock is the clock source for the
peripheral function clocks. If the sub clock is on, fC32 can be used as the count source for timers A
and B. When the operation mode is returned to the high and medium speed modes, set the CM06 bit
in the CM0 register to "1" (divided by 8 mode).
Table 10.3 Setting Clock Related Bit and Modes
Modes
PLL Operation Mode
High-Speed Mode
divided by 2
Medium-
divided by 4
Speed
Mode
divided by 8
divided by 16
Low-Speed Mode
Low Power Dissipation Mode
divided by 1
On-chip
divided by 2
Oscillator
divided by 4
Mode
divided by 8
divided by 16
On-chip Oscillator Low Power
Dissipation Mode
NOTES :
1. When the CM05 bit is set to "1" (main clock turned off) in low-speed mode, the mode goes to low power
dissipation mode and CM06 bit is set to "1" (divided by 8 mode) simultaneously.
2. The divide-by-n value can be selected the same way as in on-chip oscillator mode.
10.4.2 Wait Mode
In wait mode, the CPU clock is turned off, so are the CPU (because operated by the CPU clock) and the
watchdog timer. However, if the PM22 bit in the PM2 register is "1" (on-chip oscillator clock for the
watchdog timer count source), the watchdog timer remains active. Because the main clock, sub clock
and on-chip oscillator clock all are on, the peripheral functions using these clocks keep operating.
10.4.2.1 Peripheral Function Clock Stop Function
If the CM02 bit in the CM0 register is "1" (peripheral function clocks turned off during wait mode), the
f1, f2, f8, f32, f1SIO, f8SIO, f32SIO and fAD clocks are turned off when in wait mode, with the power
consumption reduced that much. However, fC32 remains on.
10.4.2.2 Entering Wait Mode
The microcomputer is placed into wait mode by executing the WAIT instruction.
When the CM11 bit = 1 (CPU clock source is the PLL clock), be sure to clear the CM11 bit in the CM1
register to "0" (CPU clock source is the main clock) before going to wait mode. The power consump-
tion of the chip can be reduced by clearing the PLC07 bit in the PLC0 register to "0" (PLL stops).
10.4.2.3 Pin Status During Wait Mode
Table 10.4 lists pin status during wait mode
10.4.2.4 Exiting Wait Mode
The microcomputer is moved out of wait mode by a hardware reset, NMI interrupt or peripheral func-
tion interrupt.
If the microcomputer is to be moved out of exit wait mode by a hardware reset or NMI interrupt, set the
peripheral function interrupt priority ILVL2 to ILVL0 bits to "000b" (interrupts disabled) before execut-
ing the WAIT instruction.
The peripheral function interrupts are affected by the CM02 bit. If CM02 bit is "0" (peripheral function
clocks not turned off during wait mode), 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 wait mode.
R
e
. v
2
3 .
0
S
e
p
0
, 1
2
0
0
4
R
E
J
0
9
B
0
1
8
5
0 -
2
3
0
Z
CM2 Register
CM1 Register
CM21
CM11
CM17, CM16
0
1
00b
0
0
00b
0
0
01b
0
0
10b
0
0
0
0
11b
0
0
0
1
0
00b
1
0
01b
1
0
10b
1
0
1
0
11b
1
0
(NOTE 2)
page 78
f o
3
6
4
CM0 Register
CM07
CM06
CM05
CM04
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
1
1
(1)
(1)
1
1
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
(NOTE 2)
1
: "0" or "1"
______
10. Clock Generating Circuit
______
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