Rev. 1.0, 02/00, page 737 of 1141
Horizontal Sync Signal Threshold Register (HTR)
0
0
1
0
W
2
0
W
3
0
4
5
6
1
7
—
—
—
—
—
—
—
—
W
W
HTR3
HTR2
HTR1
HTR0
1
1
1
Bit :
Initial value :
R/W :
HTR is an 8-bit write-only register that sets the threshold for the horizontal sync signal when the
signal is detected from the composite sync signal. The threshold is set by bits 3 to 0 (HTR3 to
HTR0). Bits 7 and 4 are reserved. If a read is attempted, an undetermined value is read out. It is
initialized to H'F0 by a reset, or in stand-by or module stop mode.
Figure 26.73 shows the threshold values and separated sync signals.
[Legend]
TH
Hpuls
T H
SEPV
Hpuls
: Period of the horizontal sync signal (NTSC: 63.6, PAL: 64 [
µ
s])
: Pulse width of the horizontal sync signal (NTSC, PAL: 4.7 [
µ
s])
VVTH
HVTH
: Value set as the threshold of the vertical sync signal
: Value set as the threshold of the horizontal sync signal
SEPV
SEPH
: Detected vertical sync signal
: Detected horizontal sync signal (before complement)
T H
SEPH
Csync
H'00
Counter value
1/2 Hpuls
VD interrupt
Hpuls
VVTH
HVTH
Figure 26.73 Threshold Values and Separated Sync Signals