Renesas Hitachi H8S/2191, Hardware Manual

Page: 704 / 1065

Rev. 2.0, 11/00, page 677 of 1037
28.5 Four-head High-speed Switching Circuit for Special Playback
28.5.1 Overview
This four-head high-speed switching circuit generates a color rotary signal (C.Rotary) and head-
amplifier switching signal (H.Amp SW) for use in four-head special playback.
A pre-amplifier output comparison result signal is input from the COMP pin. The signal output
at the C.Rotary pin is a Chroma signal processing control signal. The signal output at the
H.Amp SW pin is a pre-amplifier output select signal. To reduce the width of noise bars, the
C.Rotary and H.Amp SW signals are synchronized to the horizontal sync signal (OSCH). OSCH
is made by adding supplemented H, which has been separated from the Csync signal in the sync
signal detector circuit. For more details of OSCH, see section 28.15, Sync Signal Detector.
If the C.Rotary, H.Amp SW or COMP pin does not require this circuit to configure a VCR
system, it can be used as an I/O port.
28.5.2 Block Diagram
Figure 28.26 shows the block diagram of this circuit.
W W
Synchronization
control
· CHCR
W
· CHCR
RTP0
H.Amp SW
C.Rotary
OSCH
(Synchronization)
COMP
Narrow.FF
Video.FF
W
· CHCR
Internal bus
Internal bus
HAH CRH
W
· CHCR
SIG3 to 0
HSWPOL V/N
Decoding circuit
Figure 28.26 Four-Head High-Speed Switching Circuit for Special Playback