Renesas Hitachi H8S/2191, Hardware Manual

Page: 660 / 1065

Rev. 2.0, 11/00, page 633 of 1037
(3) Reference Period Register 2 (CRF)
15
1
CRF15
W
14
1
CRF14
W
13
1
CRF13
W
12
1
CRF12
W
11
1
CRF11
W
10
1
CRF10
W
9
1
CRF9
W
8
1
CRF8
W
7
1
CRF7
W
6
1
CRF6
W
5
1
CRF5
W
4
1
CRF4
W
3
1
CRF3
W
2
1
CRF2
W
1
1
CRF1
W
0
1
CRF0
W
Bit :
Initial value :
R/W :
The reference period register 2 (CRF) is a 16-bit write-only buffer register which generates the
reference signals to control the capstan phase (CREF). CRF is accessibly by a word only. If a
read is attempted, an undetermined value is read out. The value set in CRF should be 1/2 of the
desired reference signal period.
When data is written in CRF, it is stored in the buffer once, and then fetched into CRF by a
match signal of the comparator. (The data which generates the reference signal is updated from
time to time by the match signal.) An enforced write, such as initial setting, etc., should be done
by a dummy read of CRF.
If a byte-write in CRF is attempted, no operation is assured. CRF is initialized to H'FFFF by a
reset, stand-by, or module stop.
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. (See section 28.9, Capstan Phase Error
Detector)
(4) REF30 Counter Register (RFC)
15
0
RFC15
14
0
RFC14
13
0
RFC13
12
0
RFC12
11
0
RFC11
10
0
RFC10
9
0
RFC9
8
0
RFC8
7
0
RFC7
6
0
RFC6
5
0
RFC5
4
0
RFC4
3
0
RFC3
2
0
RFC2
1
0
RFC1
0
0
RFC0
R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
Bit :
Initial value :
R/W :
The REF30 counter register (RFC) is a register which determines the initial value of the free-run
counter when it generates REF30 signals when in playback. When data is written in RFC, its
value is written in the counter by a match signal of the comparator. If bit 1 (VST) in RFM is set
to 1, the counter is set by the Video FF signal when the drum phase is in FIX ON. The counter
setting by the Video FF signal should be done by setting RFM's bit 1 (VST) and bit 0 (VEG).
Don't set the RFC value at a value greater than 1/2 of the reference period register 1 (RFD).
RFC is a read/write register. If a read is attempted, the value of the counter is read out. If a
byte-access is attempted, no operation is assured. RFC is initialized to H'0000 by a reset, stand-
by, or module stop.