On-Chip Oscillator Mode; On-Chip Oscillator Low Power Dissipation Mode; Wait Mode; Peripheral Function Clock Stop Function - Renesas M16C/29 Series Hardware Manual

M16C/29 Group

7.6.1.6 On-chip Oscillator Mode

The selected on-chip oscillator clock divided by 1 (undivided), 2, 4, 8 or 16 provides the CPU clock.
The on-chip oscillator clock is also the clock source for the peripheral function clocks. If the sub clock
is on, f can be used as the count source for timers A and B. The on-chip oscillator frequency can be
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selected using the on-chip oscillator control register (ROCR:025C
details. When the operation mode is returned to the high and medium speed modes, set the CM06 bit
to "1" (divided by 8 mode).

7.6.1.7 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, f
B.
Table 7.6.1.1. Setting Clock Related Bit and Modes
Modes
PLL operation mode
High-speed mode
Medium- divided by 2
speed
divided by 4
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
(Note 3)
divided by 16
On-chip oscillator low power
dissipation mode
Note 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.
Note 2: The divide-by-n value can be selected the same way as in on-chip oscillator mode.
Note 3: Variable on-chip oscillator frequency can be any of those described in the section "Variable On-chip Oscillator Mode".

7.6.2 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 of 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, on-chip
oscillator clock and PLL clock all are on, the peripheral functions using these clocks keep operating.

7.6.2.1 Peripheral Function Clock Stop Function

If the CM02 bit is "1" (peripheral function clocks turned off during wait mode), the f
f , f , f
8SIO 32SIO
reduced that much. However, f

7.6.2.2 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 to "0"
(CPU clock source is the main clock) before going to wait mode. The power consumption of the chip
can be reduced by clearing the PLC07 bit to "0" (PLL stops).
Rev.1.00 Nov 01,2004
REJ09B0101-0100Z
CM2 register
CM21 CM11
0 1
0 0
0 0
0 0
0 0
0 0
1
1
1
1
1
1
and f clocks are turned off when in wait mode, with the power consumption
CAN0 AD
remains on.
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can be used as the count source for timers A and
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CM1 register
CM17, CM16 CM07
00 0
2
00 0
2
01 0
2
10 0
2
0
11 0
2
1
1
00 0
2
01 0
2
10 0
2
0 0
11 0
2
(Note 2) 0
7. Clock Generation Circuit
) bits 0 to 3. See Figure.7.4 for
16
CM0 register
CM06 CM05 CM04
0 0
0 0
0 0
0 0
1 0
0 0
0 1
1(Note 1) 1(Note 1) 1
0 0
0 0
0 0
1 0
0 0
(Note 2) 1
, f , f
1 2
, f , f ,
8 32 1SIO