Renesas M16C User Manual

Rev.1.10    Jul 01, 2005    page 38 of 318
REJ09B0124-0110

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

7. Clock Generating Circuit

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

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Bit Name

Function

Bit Symbol

CM10

CM15

CM16

CM17

CM11

-

(b4-b2)

All Clock Stop Control 
Bit 

(2) (3)

XIN-XOUT Drive Capacity
Select Bit 

(6)

Reserved Bit

Main Clock Division
Select Bit 1 

(7)

System Clock Select Bit 1 

(4)

0 : Clock on
1 : All clocks off (stop mode)

0 : LOW
1 : HIGH

Set to "0"

0 0 : No division mode
0 1 : Division by 2 mode
1 0 : Division by 4 mode
1 1 : Division by 16 mode

b7 b6

0 : Main clock
1 : PLL clock 

(5)

Symbol

 

Address

After Reset

CM1

0007h

00100000b

System Clock Control Register 1 

(1)

0

0 0

b7

b6

b5

b4

b3

b2

b1

b0

NOTES:

1. Write to this register after setting the PRC0 bit in the PRCR register to "1" (write enable)
2. If the CM10 bit is "1" (stop mode), XOUT goes "H" and the internal feedback resistor is disconnected. 

The XCIN and XCOUT pins are placed in the high-impedance state. When the CM11 bit is set to "1" (PLL 
clock), or the CM20 bit in the CM2 register is set to "1" (oscillation stop, re-oscillation detection function enabled), 
do not set the CM10 bit to "1".

3. When the PM22 bit in the PM2 register is set to "1" (watchdog timer count source is on-chip oscillator clock), 

writing to the CM10 bit has no effect.

4. Effective when the CM07 bit is "0" and the CM21 bit is "0".
5. After setting the PLC07 bit in the PLC0 register to "1" (PLL operation), wait until tsu(PLL) elapses before 

setting the CM11 bit to "1" (PLL clock).

6. When entering stop mode from high- or medium-speed mode, or when the CM05 bit is set to "1" (main clock 

turned off) in low-speed mode, the CM15 bit is set to "1" (drive capability high).

7. Effective when the CM06 bit is "0" (CM16 and CM17 bits enabled).