M30201 datasheet(21/172 Pages) RENESAS

21 / 172 page

Clock Generating Circuit

Mitsubishi microcomputers

M30201 Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Figure 1.18 shows the system clock control registers 0 and 1.

Figure 1.18. Clock control registers 0 and 1

System clock control register 0 (Note 1)

Symbol

Address

When reset

CM0

000616

4816

Bit name

Function

Bit symbol

b4 b3

0 0 : I/O port P54

0 1 : fC output

1 0 : f8 output

1 1 : Clock divide counter output

b1 b0

CM07

CM05

CM04

CM03

CM01

CM02

CM00

CM06

Clock output function

select bit

WAIT peripheral function

clock stop bit

0 : Do not stop peripheral function clock in wait mode

1 : Stop peripheral function clock in wait mode (Note 8)

XCIN-XCOUT drive capacity

select bit (Note 2)

0 : LOW

1 : HIGH

Port XC select bit

0 : I/O port

1 : XCIN-XCOUT generation

Main clock (XIN-XOUT)

stop bit (Note 3,4,5)

0 : On

1 : Off

Main clock division select

bit 0 (Note 7)

0 : CM16 and CM17 valid

1 : Division by 8 mode

System clock select bit

(Note 6)

0 : XIN, XOUT

1 : XCIN, XCOUT

Note 1: Set bit 0 of the protect register (address 000A16) to “1” before writing to this register.

Note 2: Changes to “1” when shifting to stop mode and at a reset.

Note 3: This bit is used to stop the main clock when placing the device in a low-power mode. If you want to operate with XIN

after exiting from the stop mode, set this bit to “0”. When operating with a self-excited oscillator, set the system clock

select bit (CM07) to “1” before setting this bit to “1”.

Note 4: When inputting external clock, only clock oscillation buffer is stopped and clock input is acceptable.

Note 5: If this bit is set to “1”, XOUT turns “H”. The built-in feedback resistor remains being connected, so XIN turns pulled up to

XOUT (“H”) via the feedback resistor.

Note 6: Set port Xc select bit (CM04) to “1” and stabilize the sub-clock oscillating before setting to this bit from “0” to “1”.

Do not write to both bits at the same time. And also, set the main clock stop bit (CM05) to “0” and stabilize the main clock

oscillating before setting this bit from “1” to “0”.

Note 7: This bit changes to “1” when shifting from high-speed/medium-speed mode to stop mode and at a reset. When shifting

from low-speed/low power dissipation mode to stop mode, the value before stop mode is retained.

Note 8: fC32 is not included. Do not set to “1” when using low-speed or low power dissipation mode.

System clock control register 1 (Note 1)

Symbol

Address

When reset

CM1

000716

2016

Bit name

Function

Bit symbol

b4 b3

CM10

All clock stop control bit

(Note 4)

0 : Clock on

1 : All clocks off (stop mode)

CM15

XIN-XOUT drive capacity

select bit (Note 2)

0 : LOW

1 : HIGH

CM16

CM17

Reserved bit

Always set to

“0”

Reserved bit

Always set to

“0”

Main clock division

select bit 1 (Note 3)

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

Reserved bit

Always set to

“0”

Reserved bit

Always set to

“0”

Note 1: Set bit 0 of the protect register (address 000A16) to “1” before writing to this register.

Note 2: This bit changes to “1” when shifting from high-speed/medium-speed mode to stop mode and at a reset. When shifting

from low-speed/low power dissipation mode to stop mode, the value before stop mode is retained.

Note 3: Can be selected when bit 6 of the system clock control register 0 (address 000616) is “0”. If “1”, division mode is fixed at 8.

Note 4: If this bit is set to “1”, XOUT turns “H”, and the built-in feedback resistor is cut off. XCIN and XCOUT turn high-impedance state.

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