lf3338 LOGIC Devices Incorporated, lf3338 Datasheet - Page 5

• Manufacturer Part Number: lf3338
• Description: 8-bit Vertical Digital Image Filter
• Manufacturer: LOGIC Devices Incorporated

DEVICES INCORPORATED
FUNCTIONAL DESCRIPTION
Line Buffers
The maximum delay length of each line
buffer is 3076 cycles and the minimum
is 4 cycles. Configuration Register 0
(CR
the line buffers. The line buffer length
is equal to the value of CR
value of 0 for CR
length to 4. A value of 3072 for CR
sets the line buffer length to 3076. Any
values for CR
valid.
The line buffers have two modes of
operation: delay mode and recirculate
mode. Bit 0 of Configuration Register 1
determines which mode the line buffers
are in. In delay mode, the data input to
the line buffer is delayed by an amount
determined by CR
mode, the output of the line buffer is
routed back to the input of the line
buffer allowing the line buffer contents
to be read multiple times.
Bit 1 of Configuration Register 1 allows
the line buffers to be loaded in parallel.
When Bit 1 is “1”, the input register
(DIN
F
IGURE
DIN
0
) determines the delay length of
7-0
8
) loads all seven line buffers in
5.
0
greater than 3072 are not
VERTICAL FILTER
LINE BUFFERS
0
M
LF3338
CIRCUIT
sets the line buffer
0
RSL
ULTIPLE
. In recirculate
0
plus 4. A
LF3338
COUT
0
DIN
S
C
ASCADED
parallel. This allows all the line buffers
to be preloaded with data in the
amount of time it normally takes to
load a single line buffer.
Odd and Even Field Filtering
The LF3338 is capable of odd and even
field filtering. Bit 2 of Configuration
Register 1 enables the VB Data Input
port required for odd and even field
filtering. Bit 3 of the same configura-
tion register enables the line buffer in
the VB Data path. Line buffer length is
set to the length written to Configura-
tion Register 0. If line buffer parallel
load is enabled and odd and even field
filtering is enabled, the data for the VB
line buffer comes from the VB Data
Input port.
Interleaved Data
The LF3338 is capable of handling
interleaved data. The number of data
sets it can handle is determined by the
number of data values contained in a
video line. If the interleaved video line
has 3076 data values or less, the LF3338
can handle it no matter how many data
sets are interleaved together.
VERTICAL FILTER
LINE BUFFERS
LF3338
CIRCUIT
RSL
T
OGETHER
29 TAP RESULT
COUT
25
5
LF3347
DATA OUT
CIRCUIT
16
RSL
DIN
25
8-Bit Vertical Digital Image Filter
VERTICAL FILTER
LINE BUFFERS
LF3338
CIRCUIT
RSL
Cascading
A cascade port is provided to allow
cascading of multiple devices for
more filter taps (see Figure 5).
COUT
connected to DIN
device. As many LF3338s as desired
may be cascaded together. How-
ever, the outputs of the LF3338s
must be added together with exter-
nal adders.
The first line buffer on a cascaded
device must have its length short-
ened by two delays. This is to
account for the added delays of the
input register on the device and the
cascade output register from the
previous LF3338. If Bit 0 of Con-
figuration Register 3 is set to “1”,
the length of the first line buffer will
be reduced by two. This will make
its effective length the same as the
other line buffers on the device. If
Bit 0 of Configuration Register 3 is
set to “0”, the length of the first line
buffer will be the same as the other
line buffers. When cascading
devices, the first LF3338 should
have Bit 0 of Configuration Register
Video Imaging Products
7-0
COUT
of one device should be
DIN
7-0
VERTICAL FILTER
LINE BUFFERS
of another
LF3338
04/06/1999–LDS.3338-B
CIRCUIT
RSL
LF3338