6
4554 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
PRELIMINAR
Y
Notice:
This
is not
a final
specification.
Some
parametric
limits
are
subject
to change.
DEFINITION OF CLOCK AND CYCLE
q Operation source clock
The operation source clock is the source clock to operate this
product. In this product, the following clocks are used.
Clock (f(XIN)) by the external ceramic resonator
Clock (f(XIN)) by the external RC oscillation
Clock (f(XIN)) by the external input
Clock (f(RING)) of the ring oscillator which is the internal oscil-
lator
Clock (f(XCIN)) by the external quartz-crystal oscillation
Register MR
System clock
f(STCK) = f(XIN) or f(RING)
f(STCK) = f(XCIN)
f(STCK) = f(XIN)/2 or f(RING)/2
f(STCK) = f(XCIN)/2
f(STCK) = f(XIN)/4 or f(RING)/4
f(STCK) = f(XCIN)/4
f(STCK) = f(XIN)/8 or f(RING)/8
f(STCK) = f(XCIN)/8
Table Selection of system clock
Note: The f(RING)/8 is selected after system is released from reset.
MR2
0
1
0
1
MR3
0
1
Operation mode
High-speed through mode
Low-speed through mode
High-speed frequency divided by 2 mode
Low-speed frequency divided by 2 mode
High-speed frequency divided by 4 mode
Low-speed frequency divided by 4 mode
High-speed frequency divided by 8 mode
Low-speed frequency divided by 8 mode
q System clock (STCK)
The system clock is the basic clock for controlling this product.
The system clock is selected by the clock control register MR
shown as the table below.
q Instruction clock (INSTCK)
The instruction clock is the basic clock for controlling CPU. The
instruction clock (INSTCK) is a signal derived by dividing the
system clock (STCK) by 3. The one instruction clock cycle gen-
erates the one machine cycle.
q Machine cycle
The machine cycle is the standard cycle required to execute the
instruction.
MR0
0
1
0
1
0
1
0
1
MR1
0
0 or 1
0
0 or 1
0
0 or 1
0
0 or 1
Notes 1: Pins except above have just single function.
2: The output of D8 and D9 can be used even when INT0 and INT1 are selected.
3: The input/output of D7 can be used even when CNTR0 (input) is selected.
4: The input of D7 can be used even when CNTR0 (output) is selected.
5: The port C “H” output function can be used even when CNTR1 (output) is selected.
Pin
C
D7
D8
D9
VLC3
VLC2
VLC1
Multifunction
CNTR1
CNTR0
INT0
INT1
SEG0
SEG1
SEG2
MULTIFUNCTION
Pin
CNTR1
CNTR0
INT0
INT1
SEG0
SEG1
SEG2
Multifunction
C
D7
D8
D9
VLC3
VLC2
VLC1
Pin
P20
P21
P22
P23
P30
P31
P32
P33
Multifunction
SEG31
SEG30
SEG29
SEG28
SEG27
SEG26
SEG25
SEG24
Pin
SEG31
SEG30
SEG29
SEG28
SEG27
SEG26
SEG25
SEG24
Multifunction
P20
P21
P22
P23
P30
P31
P32
P33