Sharp FDD-412A - Page 23

FDD412A/B
2.5.2
..
Seek
Operations
(1)
Interface
signals
Table
2.9
Interface
Signals
for
Seek
Operation
Signal
Name
Func
tion
Remarks
STEP-N
Pulse
signal
to
direct
track
movement.
One
pulse
causes
1
track
for
movement.
STEP
DIRECTION-N
|
Level
signal
to
direct
movement
:
direction.
H
:
Centrifugal
movement
L
:
Centripetal
movement
(2)
Outline
of
operation
Operation
flow
Condition
Description
Command
from
FDC
STEP-N
The
FDC
calculates
the
positional
|
STEP
DETECTION-N
|
difference
between
the
current
and
new track positions, and signals
the absolute amount of displacement.
Operation
mode
Not
in
write
Seek
operation
is
inhibited
for
check
in
FDD
mode
580
us
following
WRITE
GATE-N
(directing write mode).
Of the 4 phases of step motor
winding, 2 phases are driven at a
time.
Step motor
switched for
exciting phase
control
approx.
0.5 mm/step
Head positioned
Fig. 2.11 Outline of Seek Operation
(3)
Seek
circuit
block
diagram
aye