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Rev.2.00 Nov 28, 2005 page 70 of 378
REJ09B0124-0200
M16C/6N Group (M16C/6NK, M16C/6NM) 8. Clock Generating Circuit
Under development
This document is under development and its contents are subject to change.
8.4.1.6 On-chip Oscillator Mode
The 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 activated,
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” (divide-by-8 mode).
8.4.1.7 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 like 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 activated, fC32 can be used as the count source for timers
A and B.
Table 8.3 lists the setting clock related bit and modes.
Table 8.3 Setting Clock Related Bit and Modes
Modes
CM2 Register
CM1 Register CM0 Register
CM21 CM11
CM17
,
CM16
CM07 CM06 CM05 CM04
PLL Operation Mode 0 1 00b 0 0 0 -
High-Speed Mode 0 0 00b 0 0 0 -
Medium-
Divide-by-2
0 0 01b 0 0 0 -
Speed
Divide-by-4
0 0 10b 0 0 0 -
Mode
Divide-by-8
00-010-
Divide-by-16
0 0 11b 0 0 0 -
Low-Speed Mode - 0 - 1 - 0 1
Low Power 0 0 - 1 1
(1)
1
(1)
1
Dissipation Mode
On-chip
Divide-by-1
1 0 00b 0 0 0 -
Oscillator
Divide-by-2
1 0 01b 0 0 0 -
Mode
Divide-by-4
1 0 10b 0 0 0 -
Divide-by-8
10-010-
Divide-by-16
1 0 11b 0 0 0 -
On-chip Oscillator 1 0 (NOTE 2) 0 (NOTE 2) 1 -
Low power Dissipation
Mode
-: “0” or “1”
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 the CM06 bit is set to “1” (divide-by-8 mode) simultaneously.
2. The divide-by-n value can be selected the same way as in on-chip oscillator mode.