Rev. 1.0, 02/00, page 571 of 1141
Bit 1
Video FF Counter Set (VST): Selects whether the REF30 counter register value is set on
or off by the Video FF signal when the drum phase is in FIX on in the PB mode.
Bit 1
VST
Description
0
Counter set off by Video FF signal
(Initial value)
1
Counter set on by Video FF signal
Bit 0
Video FF Edge Selection Bit (VEG): Selects the edge at which REF30 counter is set
(VST = 1) by the Video FF signal.
Bit 0
VEG
Description
0
Set at the rising edge of Video FF signal
(Initial value)
1
Set at the falling edge of Video FF signal
Reference Period Register 1 (RFD)
15
1
REF15
W
14
1
REF14
W
13
1
REF13
W
12
1
REF12
W
11
1
REF11
W
10
1
REF10
W
9
1
REF9
W
8
1
REF8
W
7
1
REF7
W
6
1
REF6
W
5
1
REF5
W
4
1
REF4
W
3
1
REF3
W
2
1
REF2
W
1
1
REF1
W
0
1
REF0
W
Bit :
Initial value :
R/W :
The reference period register 1 (RFD) is a buffer register which generates the reference signal
(REF30) for playback, VD compensation for recording, and the reference signals for free-running.
It is an 16-bit write-only register accessible in word units only. If a read is attempted, an
undetermined value is read out.
The value set in RFD should be 1/2 of the desired reference signal period. Care is required when
VD is unstable, such as when the field is weak (synchronization with VD cannot be acquired if a
value less than 1/2 is set in REC). When data is written in RFD, it is stored in the buffer once, and
then fetched into RFD by a match signal of the comparator. (The data which generates the
reference signal is updated by the match signal.) A forcible write, such as initial setting, etc.,
should be done by a dummy read of RFD.
If a byte-write in RFD is attempted, correct operation is not guaranteed. RFD is initialized to
H'FFFF by a reset, and in stand-by and module stop modes.
Use bit 7 (ASM) and bit 6 (REC/PB) in the CTL mode register (CTLM) in the CTL circuit to
switch between record and playback modes. Use bit 4 (CR/RF bit) in the capstan phase error
detection control register (CPGCR) to switch between REF30 and CREF for capstan phase
control.