
MITSUBISHI MICROCOMPUTERS
M37207MF-XXXSP/FP, M37207M8-XXXSP
M37207EFSP/FP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER
and ON-SCREEN DISPLAY CONTROLLER
71
Fig. 68. CRT Clock Selection Register
(13) Clock for Display
As a clock for display to be used for CRT display, it is possible to
select one of the following 3 types.
Main clock supplied from the X
IN
pin
Clock from the LC or RC supplied from the pins OSC1 and OSC2.
Clock from the ceramic resonator or quartz-crystal oscillator sup-
plied from the pins OSC1 and OSC2.
This clock for display can be selected for each block by the CRT
clock selection register (address 0209
16
).
When selecting the main clock, set the oscillation frequency to
8 MHz.
b7 b6 b5 b4 b3 b2 b1 b0
CRT clock selection register (OP) [Address 0209
16
]
B
Name
Functions
After reset R W
CRT Clock Selection Register
0, 1 CRT clock
selection bits
(OP0, OP1)
0
Since the main clock is used as the clock for
display, the oscillation frequency is limited.
Because of this, the character size in width
(horizontal) direction is also limited. In this
case, pins OSC1 and OSC2 are also used
as input ports P7
0
and P7
1
respectively.
The clock for display is supplied by connecting the
following across the pins OSC1 and OSC2.
a ceramic resonator only for CRT display and a feedback resistor
a quartz-crystal oscillator only for CRT display and a feedback
resistor (See note)
2
to
6
7
0
0
b1
1
The clock for display is supplied by connecting RC
or LC across the pins OSC1 and OSC2.
Functions
0
b0
CRT oscillation
frequency
= f(X
IN
)
Notes 1:
It is necessary to connect other ceramic resonator or quartz-crystal oscillator across the pins X
IN
and X
OUT
.
2:
CC6 is the scnanning line double count mode flag.
0
1
1
1
R W
R —
CC6
CC6 =
“0” or “1”
CC6 = “0”
CC6 = “0”
1
0
—
Do not set.
0
Fix this bits to “0.”
R W
Nothing is assigned. These bits are write disable bits.
When these bits are read out, the values are “0.”