M16C80 Datasheet, PDF(57/358 Page) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

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M16C80 Datasheet, PDF (57/358 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

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M16C/80 Group

8. Clock Generating Circuit

System clock control register 0 (Note 1)

b7 b6 b5 b4 b3 b2 b1 b0

Symbol

CM0

Address

000616

When reset

0816

Bit symbol

Bit name

Function

RW

CM00

CM01

Clock output function

select bit (Note 2)

b1 b0

0 0 : I/O port P53

0 1 : fC output (Note 3)

1 0 : f8 output (Note 3)

1 1 : f32 output (Note 3)

CM02

CM03

CM04

WAIT peripheral function

clock stop bit

0 : Do not stop peripheral clock in wait

mode

1 : Stop peripheral clock in wait mode

(Note 10)

XCIN-XCOUT drive capacity 0 : LOW

select bit (Note 4)

1 : HIGH

Port XC select bit

0 : I/O port

1 : XCIN-XCOUT generation (Note 11)

CM05

Main clock (XIN-XOUT)

stop bit (Note 5, 6)

0 : On

1 : Off (Note 7)

CM06

Watchdog timer function

select bit

0 : Watchdog timer interrupt

1 : Reset (Note 8)

CM07

System clock select bit

(Note 9)

0 : XIN, XOUT

1 : XCIN, XCOUT

Note 1: Set bit 0 of the protect register (address 000A16) to â1â before writing to this register.

Note 2: When outputting BCLK (bit 7 of processor mode register 0 is "0"), set these bits to "00". When

outputting ALE to P53 (bit 5 and 4 of processor mode register 0 is "01"), set these bits to "00". The

port P53 function is not selected even when you set "00" in microprocessor or memory expansion

mode and bit 7 of the processor mode register 0 is "1".

Note 3: When selecting fC, f8 or f32 in single chip mode, must use P57 as input port.

Note 4: Changes to â1â when shifting to stop mode or reset.

Note 5: When entering the power saving mode, the main clock is stopped using this bit. To stop the main

clock, set system clock stop bit (CM07) to "1" while an oscillation of sub clock is stable. Then set this

bit to "1".

Note 6: When this bit is "1", XOUT is "H". Also, the internal feedback resistance remains ON, so XIN is pulled

up to XOUT ("H" level) via the feedback resistance.

Note 7: When the main clock is stopped, the main clock division register (address 000C16) is set to the

division by 8 mode.

Note 8: When "1" has been set once, "0" cannot be written by software.

Note 9: To set CM07 "1" from "0", first set CM04 to "1", and an oscillation of sub clock is stable. Then set

CM07. Also, to set CM07 "0" from "1", first set CM05 to "1", and an oscillation of main clock is

stable. Then set CM07. Do not rewrite CM04 and CM05 simultaneously.

Note 10: fc32 is not included.

Note 11: When XcIN-XcOUT is used, set port P86 and P87 to no pull-up resistance with the input port.

System clock control register 1 (Note 1)

b7 b6 b5 b4 b3 b2 b1 b0

00

0000

Symbol

CM1

Address

000716

When reset

2016

Bit symbol

Bit name

CM10

All clock stop control bit

(Note 3)

Reserved bit

CM15

XIN-XOUT drive capacity

select bit (Note 2)

Reserved bit

Function

0 : Clock on

1 : All clocks off (stop mode) (Note 4)

Always set to â0â

RW

Always set to â0â

Note 1: Set bit 0 of the protect register (address 000A16) to â1â before writing to this register.

Note 2: Changes to â1â when shifting from high-speed or middle-speed mode to stop mode or reset.

This bit is remained in low speed or low power dissipation mode.

Note 3: When this bit is "1", XOUT is "H", and the internal feedback resistance is disabled. XCIN and

XCOUT are high-inpedance.

Note 4: When the main clock is stopped, the main clock division register (address 000C16) is set to the

division by 8 mode.

Figure 8.4 System clock control registers 0 and 1

Rev.1.00 Aug. 02, 2005 Page 46 of 329

REJ09B0187-0100

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