DEVICES INCORPORATED
LF3338
8-Bit Vertical Digital Image Filter
LF3338
DEVICES INCORPORATED
FEATURES DESCRIPTION
❑❑
❑ 83 MHz Data Rate
❑❑
❑❑
❑ 8-bit Data and 12-bit Coefficients
❑❑
❑❑
❑ Supports Interleaved Data Streams
❑❑
❑❑
❑ Cascadable for More Filter Taps
❑❑
❑❑
❑ Seven 3K x 8-bit, Dynamic Program-
❑❑
mable Two-Mode Line Buffers
❑❑
❑ On-board Memory for 256
❑❑
Coefficient Sets
❑❑
❑ LF Interface
❑❑
TM
Allows All 256
Coefficient Sets to be Updated
Within Vertical Blanking
❑❑
❑ Selectable 16-bit Data Output with
❑❑
User-Defined Rounding and
Limiting
❑❑
❑ Separate Input Port for Odd and
❑❑
Even Field Filtering
❑❑
❑ 8 Filter Taps
❑❑
❑❑
❑ 3.3 Volt Power Supply
❑❑
❑❑
❑ 5 Volt Tolerant I/O
❑❑
❑❑
❑ Purchase Description
❑❑
The LF3338 is a lower cost version of
the 12-bit LF3330 and is suited for
multimedia and special effects systems,
projectors, plasma display panels, scan
converters, set-top boxes, and other
consumer applications.
This device filters digital images in
the vertical dimension at real-time
video rates. Input data is 8 bits and
coefficient data is 12 bits and both are
in two’s complement format. The
output is also in two’s complement
format and may be rounded to 16 bits.
The filter is an 8-tap FIR filter with all
required line buffers contained onchip. The line buffers can store video
lines with lengths from 4 to 3076
pixels. Multiple LF3338s can be
cascaded together to create larger
vertical filters.
8-Bit Vertical Digital Image Filter
Due to the length of the line buffers,
interleaved data can be fed directly
into the device and filtered without
separating the data into individual
data streams. The number of interleaved data sets that the device can
handle is limited only by the length of
the on-chip line buffers. If the interleaved video line has 3076 data values
or less, the filter can handle it.
The LF3338 contains enough on-board
memory to store 256 coefficient sets.
The LF InterfaceTM allows all 256
coefficient sets to be updated within
vertical blanking.
Selectable 16-bit data output with
user-defined rounding and limiting
minimizes the constraints put on
coefficient sets for various filter
implementations.
LF3338 BLOCK DIAGRAM
DIN
VB
8
7-0
8
7-0
3K LINE BUFFER
3K LINE BUFFER
3K LINE BUFFER
3K LINE BUFFER
3K LINE BUFFER
3K LINE BUFFER
3K LINE BUFFER
32
8-TAP VERTICAL FILTER
256 COEFFICIENT SET STORAGE
ROUND
SELECT
LIMIT
CIRCUITRY
OED
16
15-0
DOUT
8
COUT
7-0
OEC
Video Imaging Products
1
04/06/1999–LDS.3338-B
DEVICES INCORPORATED
FIGURE 1. LF3338 FUNCTIONAL BLOCK DIAGRAM
OED
3-0
4
RSL
16
16
15-0
DOUT
LIMIT
SELECT
ROUND
LF3338
8-Bit Ver tical Digital Image Filter
ACC
Coef Bank 6 Coef Bank 5 Coef Bank 4
Coef Bank 7
"0"
22
20
20
20
12 12 12 12
8
8
8
32
22
20
8
20
8
20
20
20
12 12 12 12
8
8
8
Coef Bank 0 Coef Bank 1 Coef Bank 2 Coef Bank 3
CEN
LF
12
11-0
CF
INTERFACE
LD
PAUSE
CONFIGURATION AND
CONTROL REGISTERS
CLK
3K Line Buffer
3K Line Buffer
3K Line Buffer
SHEN
8
7-0
DIN
8
7-0
CA
3K Line Buffer
8
7-0
VB
3K Line Buffer
3K Line Buffer
3K Line Buffer
8
7-0
OEC
COUT
Video Imaging Products
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04/06/1999–LDS.3338-B
DEVICES INCORPORATED
765 210
–2
7
(Sign)
262
5
22212
0
11 10 9 2 1 0
–2
0
(Sign)
2–12
–2
2–92
–102–11
Input Data Coefficient Data
LF3338
8-Bit Vertical Digital Image Filter
SIGNAL DEFINITIONS
Power
VCC and GND
+3.3 V power supply. All pins must be
connected.
Clock
CLK — Master Clock
The rising edge of CLK strobes all
enabled registers.
Inputs
DIN7-0 — Data Input
DIN7-0 is the 8-bit registered data input
port. Data is latched on the rising edge
of CLK.
VB7-0 — Field Filtering Data Input
VB7-0 is the 8-bit registered data input
port used only when implementing
Odd and Even Field Filtering (see
Functional Description section for a full
discussion). Data is latched on the
rising edge of CLK.
CF11-0 — Coefficient Input
CF11-0 is used to load data into the
coefficient banks and configuration/
control registers. Data present on
CF11-0 is latched into the LF Interface
on the rising edge of CLK when LD is
LOW (see the LF InterfaceTM section for
a full discussion).
CA7-0 — Coefficient Address
CA7-0 determines which row of data in
the coefficient banks is fed to the
multipliers. CA7-0 is latched into the
Coefficient Address Register on the
rising edge of CLK when CEN is LOW.
Outputs
DOUT15-0 — Data Output
DOUT15-0 is the 16-bit registered data
output port.
FIGURE 2. INPUT FORMATS
TABLE 1. OUTPUT FORMATS
SLCT4-0 S15 S14 S13 · · · S8 S7 · · · S2 S1 S0
00000 F15 F14 F13 · · · F8 F7 · · · F2 F1 F0
00001 F16 F15 F14 · · · F9 F8 · · · F3 F2 F1
00010 F17 F16 F15 · · · F10 F9 · · · F4 F3 F2
· ··· ·· ···
· ··· ·· ···
· ··· ·· ···
01110 F29 F28 F27 · · · F22 F21 · · · F16 F15 F14
01111 F30 F29 F28 · · · F23 F22 · · · F17 F16 F15
10000 F31 F30 F29 · · · F24 F23 · · · F18 F17 F16
COUT7-0 — Cascade Data Output
COUT7-0 is a 8-bit cascade output
port. COUT7-0 on one device
should be connected to DIN7-0 of
another LF3338.
Controls
TM
LD — Coefficient Load
When LD is LOW, data on CF11-0
is latched into the LF Interface
TM
on the rising edge of CLK. When
LD is HIGH, data can not be
latched into the LF InterfaceTM.
When enabling the LF Interface
TM
for data input, a HIGH to LOW
transition of LD is required in
order for the input circuitry to
function properly. Therefore, LD
must be set HIGH immediately
after power up to ensure proper
operation of the input circuitry
(see the LF InterfaceTM section for
a full discussion).
3
FIGURE 3. ACCUMULATOR FORMAT
Accumulator Output
31 30 29 2 1 0
16
–2
(Sign)
2152
14
–132–142–15
2
PAUSE — LF InterfaceTM Pause
When PAUSE is HIGH, the LF
InterfaceTM loading sequence is halted
until PAUSE is returned to a LOW
state. This effectively allows the user
to load coefficients and control
registers at a slower rate than the
master clock (see the LF Interface
TM
section for a full discussion).
CEN — Coefficient Address Enable
When CEN is LOW, data on CA7-0 is
latched into the Coefficient Address
Register on the rising edge of CLK.
When CEN is HIGH, data on CA7-0 is
not latched and the register’s contents
will not be changed.
Video Imaging Products
04/06/1999–LDS.3338-B
DEVICES INCORPORATED
LF3338
8-Bit Ver tical Digital Image Filter
TABLE 2. CONFIGURATION REGISTER 0 – ADDRESS 200H
BITS FUNCTION DESCRIPTION
11-0 Line Buffer Length See Line Buffer Description Section
TABLE 3. CONFIGURATION REGISTER 1 – ADDRESS 201H
BITS FUNCTION DESCRIPTION
0 Line Buffer Mode 0: Delay Mode
1: Recirculate Mode
1 Line Buffer Load 0: Normal Load
1: Parallel Load
2 Odd and Even Field 0: VB Port Disabled
Filtering Port Enable 1: VB Port Enabled
3 Odd and Even Field 0: VB Line Buffer Disabled
Filtering Line Buffer Enable 1: VB Line Buffer Enabled
11-4 Reserved Must be set to “0”
TABLE 4. CONFIGURATION REGISTER 2 – ADDRESS 202H
BITS FUNCTION DESCRIPTION
0 Limit Enable 0: Limiting Disabled
1: Limiting Enabled
11-1 Reserved Must be set to “0”
FIGURE 4. RSL CIRCUITRY
RSL
3-0
4
R0R15
S0S15
L0L15
DATA IN
32
32
RND
32
5
SELECT
16
32
LIMIT
TABLE 5. CONFIGURATION REGISTER 3 – ADDRESS 203H
BITS FUNCTION DESCRIPTION
0 Cascade Mode 0: First Device
1: Cascaded Device
11-1 Reserved Must be set to “0”
ACC — Accumulator Control
When ACC is HIGH, the accumulator
is enabled for accumulation and the
accumulator output register is
disabled for loading. When ACC is
LOW, no accumulation is performed
and the accumulator output register
is enabled for loading. ACC is
latched on the rising edge of CLK.
SHEN — Shift Enable
SHEN enables or disables the
loading of data into the input/
cascade registers and the line
buffers. When SHEN is LOW, data
is loaded into the input/cascade
registers and shifted through the
line buffers on the rising edge of
CLK. When SHEN is HIGH, data
can not be loaded into the input/
cascade registers or shifted through
the line buffers and their contents
will not be changed.
RSL3-0 — Round/Select/Limit Control
RSL3-0 determines which of the
sixteen user-programmable round/
select/limit registers are used in the
round/select/limit circuitry. A
value of 0 on RSL3-0 selects round/
select/limit register 0. A value of 1
selects round/select/limit register 1
and so on. RSL3-0 is latched on the
RSL CIRCUITRY
16
DATA OUT
rising edge of CLK (see the round,
select, and limit sections for a
complete discussion).
OED — DOUT Output Enable
When OED is LOW, DOUT15-0 is
enabled for output. When OED is
HIGH, DOUT15-0 is placed in a
high-impedance state.
OEC — COUT Output Enable
When OEC is LOW, COUT7-0 is
enabled for output. When OEC is
HIGH, COUT7-0 is placed in a highimpedance state.
Video Imaging Products
4
04/06/1999–LDS.3338-B
DEVICES INCORPORATED
LF3338
8-Bit Vertical Digital Image Filter
FUNCTIONAL DESCRIPTION
Line Buffers
The maximum delay length of each line
buffer is 3076 cycles and the minimum
is 4 cycles. Configuration Register 0
(CR0) determines the delay length of
the line buffers. The line buffer length
is equal to the value of CR0 plus 4. A
value of 0 for CR0 sets the line buffer
length to 4. A value of 3072 for CR0
sets the line buffer length to 3076. Any
values for CR0 greater than 3072 are not
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 CR0. In recirculate
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
(DIN7-0) loads all seven line buffers in
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 configuration register enables the line buffer in
the VB Data path. Line buffer length is
set to the length written to Configuration 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.
Cascading
A cascade port is provided to allow
cascading of multiple devices for
more filter taps (see Figure 5).
COUT7-0 of one device should be
connected to DIN7-0 of another
device. As many LF3338s as desired
may be cascaded together. However, the outputs of the LF3338s
must be added together with external adders.
The first line buffer on a cascaded
device must have its length shortened 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 Configuration 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
FIGURE 5. MULTIPLE LF3338S CASCADED TOGETHER
8
DIN LINE BUFFERS
VERTICAL FILTER
RSL
CIRCUIT
COUT DIN
LINE BUFFERS LINE BUFFERS LINE BUFFERS
VERTICAL FILTER VERTICAL FILTER VERTICAL FILTER
RSL
CIRCUIT
COUT
LF3347
29 TAP RESULT
5
LF3338LF3338LF3338
DIN DIN
RSL
CIRCUIT
2525
RSL
CIRCUIT
16
DATA OUT
Video Imaging Products
COUT
LF3338
RSL
CIRCUIT
04/06/1999–LDS.3338-B