Renesas 6NM Manual Do Utilizador

Rev.1.10 Jul 01, 2005 page 49 of 318
REJ09B0124-0110

M16C/6N Group (M16C/6NK, M16C/6NM)

7. Clock Generating Circuit

Under development

This document is under development and its contents are subject to change.

7.4.1.6 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.

7.4.1.7 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. 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).

Table 7.3 lists the setting clock related bit and modes.

Table 7.3 Setting Clock Related Bit and Modes

Modes

CM2 Register

CM1 Register

CM0 Register

CM21

CM11

CM17, CM16

CM07

CM06

CM05

CM04

PLL Operation Mode

00b

High-Speed Mode

00b

Medium- divided by 2

01b

Speed

divided by 4

10b

Mode

divided by 8

divided by 16

11b

Low-Speed Mode

Low Power

(1)

Dissipation Mode

On-chip divided by 1

00b

Oscillator divided by 2

01b

Mode

divided by 4

10b

divided by 8

divided by 16

11b

On-chip Oscillator

(NOTE 2)

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.