User`s manual
77
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
MITSUBISHI MICROCOMPUTERS
Rev. 1.0
M37281MAH–XXXSP,M37281MFH–XXXSP
M37281MKH–XXXSP,M37281EKSP
Note : 1TC (TC : OSD clock cycle divided in pre-divide circuit) gap occurs be-
tween the horizontal display start position set by the horizontal position
register and the most left dot of the 1st block. Accordingly, when 2 blocks
have different pre-divide ratios, their horizontal display start position
will not match.
Ordinaly, this gap is 1T
C regardless of character sizes, however, the
gap is 1.5T
C only when the character size is 1.5TC.
Fig. 8.11.12 Notes on Horizontal Display Start Position
H
SYNC
1T
C
1T
C
Block 1 (Pre-divide ratio = 1)
1T
C
4T
OSC
✕ N
Note 1
Block 2 (Pre-divide ratio = 2)
Block 3 (Pre-divide ratio = 3)
Block 4 (Pre-divide ratio = 2, character size = 1.5Tc)
1.5T
C
: Value of horizontal position register (decimal notation)
: OSD clock cycle divided in pre-divide circuit
: OSD oscillation cycle
: 50 Tosc
N
Tc
Tosc
Tdef
T
def
The horizontal display position is common to all blocks, and can be
set in 256 steps (where 1 step is 4TOSC, TOSC being the oscillating
cycle for display) as values “0016” to “FF16” in bits 0 to 7 of the hori-
zontal position register (address 00CF16). The horizontal position reg-
ister is shown in Figure 8.11.12.
Fig. 8.11.11 Horizontal Position Register
b7 b6 b5b4 b3 b2b1 b0
Horizontal position register (HP) [Address 00CF
16]
B Name Functions
After reset
RW
Horizontal Position Register
Control bits of horizontal
display start positions
(HP0 to HP7)
Horizontal display start positions
4TOSC ✕
(setting value of high-order 4 bits ✕ 16
1
+setting value of low-order 4 bits ✕ 16
0
)
0RW
0
to
7
Notes 1. The setting value synchronizes with the V
SYNC.
2. T
OSC = OSD oscillation period.