MITSUBISHI MICROCOMPUTERS
M37271MF-XXXSP
M37271EF-XXXSP, M37271EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
36
Fig. 33. Structure of clock run-in register 1
Fig. 36. Structure of clock run-in detect registers 1and 3
Fig. 35. Window setting
Fig. 34. Structure of clock run-in register 3
For the main data slice line, the count value of pulses in the window
is stored in clock run-in register 1 (address 00E616; refer to Figure
33). For the sub-data slice line, the count value of pulses in the window
is stored in clock run-in register 3 (address 020916; refer to Figure
34). When this count value is 4 to 6, it is determined as a clock run-in.
Accordingly, set the count value so that the window may start after
the first pulse of the clock run-in (refer to Figure 35).
The contents to be set in the window register are written at a falling
of the horizontal synchronizing signal. For this reason, even if an
instruction for setting is executed, the contents of the register cannot
be rewritten until a falling of the horizontal synchronizing signal.
For the main data slice line, reference clock is counted in the period
from a falling of the clock pulse set in bits 0 to 2 of the clock run-in
detect register 2 (address 00E916) to the next falling. The count value
is stored in bits 3 to 7 of the clock run-in detect register 1 (address
00E816) (When the count value exceeds “1F16,” “1F16” is held). For
the sub-data slice line, the count value is stored in bits 3 to 7 of the
clock run-in detect register 3 (address 020816). Read out these bits
after the occurence of a data slicer interrupt (refer to (11) Interrupt
Request Generating Circuit).
Figure 36 shows the structure of clock run-in detect registers 1 and
3.
70
Clock run-in count value of sub-data
slice line
Clock run-in register 3
(CR3 : address 0209
16
)
Data latch completion flag for caption data in
sub-data slice line
0: Data is not latched yet
1: Data is latched
Data slice line selection bit for interrupt
request
0: Main data slice line
1: Sub-data slice line
Interrupt mode selection bit
0: Interrupt occurs at end of data slice line
1: Interrupt occurs at completion of caption
data latch
✽When the count value
in the window is 4 to 6,
this is determined as a
clock run-in.
Horizontal
synchronizing
signal
Composite
video signal
Window
Clock run-in
Start bit data +
16-bit data
Time to be set in the
window register
Time to be set in
the start bit position
register
70
Number of reference clocks to
be counted in one clock run-in
pulse period
Clock run-in detect registers 1, 3
( CRD1 : address 00E8
16
)
( CRD3 : address 0208
16
)
Test bits : read-only
70
Clock run-in count value of
main-data slice line
Clock run-in register 1
(CR1 : address 00E6
16
)
Fix these bits to “0101
2
”
0101
(145 Seiten)
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