270M
Rapid
Scanning Imaging Spectrograph
4.9.2
Basic
Operation
At power up reset, the STATE COUNTER is forced to STATE 4, and
all
devices are
disabled from normal operation.
The Shutter circuits default to the inactive or CLOSED positions.
The
DC
Motor Control circuits test the Direction Select Jumpers
and move the motors in the appropriate rotational direction
to
set the 4 devices
in
the
preferred positions.
The four Accessory (Slit) Stepper Motor Driver Circuits are disabled, and
the Wavelength Motor sequence counter is set to O (this
is
of
little consequence at this time).
When the RESET signal becomes inactive, If the SELECT CLOCK is
high the STATE COUNTER remains
in
STATE
4,
if SELECT CLOCK is low
the COUNTER will advance to STATE
5.
Operation
of
the controller is now completely a function
of
the
host computer. Raising and lowering the SELECT CLOCK line will
advance the STATE COUNTER with each transition, high or low. Before
the host can intelligently control the different devices, it must
first locate the INDEX (Wavelength Drive) position. This is done by
initiating a SELECT CLOCK transition and reading back the INDEX
level on pin 7
of
the
1/0
connector
P2.
This signal is high in
all
states
of
the STATE COUNTER other than STATE
0.
When this state is
reached this level goes low. When the host reads this level it may
now keep track of the·STATE COUNTER allowing itself
to
select.any
desired device and operate
it.
For example, let's say we want to open the Front Entrance Shutter.
Knowing we are at the Index position initiate the following sequence
of
events:
·
1.
·Lower and raise the SELECT LINE 3 times, after the 3rd low to high
transition lower the signal once more. (we are
now
in STATE 7)
2.
Lower the
DIR
signal (to OPEN the shutter}.
3.
Initiate a STEP pulse (lower then raise the STEP line}.
14
Revised
November
24.
1992
Leica Microsystems, Inc.'s Ex. 1033
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