Renesas Hitachi H8S/2191, Hardware Manual

Page: 784 / 1065

Rev. 2.0, 11/00, page 757 of 1037
(6) REC-CTL Duty Data Register 4 (RCDR4)
1 1 1 1
13 14 15 1 0 3 2 5 4 7 6 9 8 11 10
CMT41
W
12
— — — —
— — — —
0
CMT40
W
0
CMT43
W
0
CMT42
W
0
CMT45
W
0
CMT44
W
0
CMT47
W
0
CMT46
W
0
CMT49
W
0
CMT48
W
0
CMT4B
W
0
CMT4A
W
0
Bit :
Initial value :
R/W :
RCDR4 sets the timing of falling edge of the 0 pulse (short) of REC-CTL in record or rewrite
mode. In detection mode, it is used to detect the long/short pulse.
RCDR4 is a 12-bit write-only register. It accepts only a word-access. If a byte access is
attempted, operation is not assured. If a read is attempted, an undefined value is read out. Bits
15 to 12 are reserved, and no write in them is valid.
It is initialized to H'F000 by a reset, stand-by, module stop or CTL stop.
In record mode, set a value with the 57.5% duty cycle obtained from the transition timing T4
corresponding to the servo clock frequency
φ
s according to the following equation. See figure
28.60, REC-CTL Signal Generation Timing.
RCDR4 = T4
× φ
s/64
φ
is the servo clock frequency (= f
OSC
/2) in Hz, and T4 is the set timing (s).
At bit pattern detection, set the 0 pulse long/short threshold value at REV. See figure 28.56,
Duty Discriminator.
RCDR4 = H'FFF
−
(T4'
× φ
s/80)
φ
s is the servo clock frequency (= f
OSC
/2) in Hz, and T4' is the 0 pulse long/short threshold value
at REV (s).