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Under
development
Preliminary Specifications REV.B3
Specifications in this manual are tentative and subject to change.
Mitsubishi Microcomputers
M32C/83 group
SINGLE-CHIP 16/32-BIT CMOS MICROCOMPUTER
Watchdog Timer
108
System clock control register 0 (Note 1)
Symbol
Address
When reset
CM0
000616
0000 X0002
Bit
name
Function
Bit symbol
b7
b6
b5
b4
b3 b2
b1
b0
0 0 : I/O port P53
0 1 : fC output
1 0 : f8 output
1 1 : f32 output
b1 b0
CM07
CM05
CM04
CM01
CM02
CM00
Clock output function
select bit (Note 2)
WAIT peripheral
function clock stop bit
0 : Do not stop peripheral clock
in wait mode
1 : Stop peripheral clock in
wait mode
(Note 3)
Port XC select bit
0 : I/O port
1 : XCIN-XCOUT generation (Note 4)
Main clock (XIN-XOUT)
stop bit (Note 5)
0 : Main clock On
1 : Main clock Off (Note 6)
System clock select bit
(Note 8)
0 : XIN, XOUT
1 : XCIN, XCOUT
W
R
CM06
Watchdog timer
function select bit
0 : Watchdog timer interrupt
1 : Reset (Note 7)
Nothing is assigned.
When write, set "0". When read, their contents are indeterminate.
Note 1: Set bit 0 of the protect register (address 000A16) to “1” before writing to this register.
Note 2: The port P53 dose not function as an I/O port in microprocessor or memory expansion
mode.
When outputting ALE to P53 (bits 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: fc32 is not included. When this bit is set to "1", PLL cannot be used in WAIT.
Note 4: When XcIN-XcOUT is used, set port P86 and P87 to no pull-up resistance with the input
port.
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".
When XIN is used after returning from stop mode, set this bit to "0".
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 6: When the main clock is stopped, the main clock division register (address 000C16) is set
to the division by 8 mode.
However, in ring oscillator mode, the main clock division register is not set to the division
by 8 mode when XIN-XOUT is stopped by this bit.
Note 7: When "1" has been set once, "0" cannot be written by software.
Note 8: Set this bit "0" to "1" when sub clock oscillation is stable by setting CM04 to "1".
Set this bit "1" to "0" when main clock oscillation is stable by setting CM05 to "0".
Do not set CM04 and CM05 simultaneously.
Figure 1.10.3. System clock control register 0