Table of Contents
Advertisement
APPENDIX
6.7 Control registers
CRT Clock Selection Register
b7 b6 b5 b4 b3 b2 b1 b0
0
0
0
0
0
Note: It is necessary to connect other ceramic resonator or quartz-crystal oscillator across the pins X
Fig. 6.7.21 CRT clock selection register
6-44
0
CRT clock selection register (CK) [Address 00ED
B
Name
b1
0, 1 CRT clock
selection bits
1
(CK0,CK1)
0
1
1
2
Fix these bits to "0."
to
7
7220 Group User's Manual
]
16
Functions
b0
Functions
0
The clock for display is supplied by connecting RC
or LC across the pins OSC1 and OSC2.
1
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
0
case, pins OSC1 and OSC2 are also used
as input ports P3
and P3
respectively.
3
4
1
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 (Note)
After reset R W
0
R W
CRT oscillation
frequency
= f(X
)
IN
CRT oscillation
frequency
= f(X
)/1.5
IN
0
R W
and X
.
IN
OUT
Address 00ED
16
Advertisement
Table of Contents
