lf3320 LOGIC Devices Incorporated, lf3320 Datasheet - Page 9

• Manufacturer Part Number: lf3320
• Description: Horizontal Digital Image Filter
• Manufacturer: LOGIC Devices Incorporated

DEVICES INCORPORATED
Coefficient Mode. However, there are
some special considerations when this
mode is desired. The LF3320 must be
configured for single filter mode only,
for a maximum (8x8) matrix. The user
must disable the cascaded filter mode,
the accumulator access mode, and the
data reversal (see Table 7).
Double Wide Data/Coefficient Mode
The LF3320 is capable of supporting
24-bit data and 12-bit coefficients or
12-bit data and 24-bit coefficients.
When configured for this mode of
operation, the Filter B output is scaled
by 2
A output. This mode of operation is
only valid in single filter mode.
To configure the LF3320 for this mode,
bit 3 of Configuration Register 5 must
be set to 1; this will account for
the scaling function (Table 7). For
24-bit data, DIN11-0 becomes the MSB
(Filter A) and RIN11-0 becomes the
LSB (Filter B), bit 2 of Configuration
Register 5 must be set to 0. To
insure correct results, the coefficient
sets must be aligned appropriately;
that is to say, the coefficient set used
for the MSB must be the same for the
LSB. For 24-bit coefficients, the coef-
ficient banks for Filter A will corre-
spond to the coefficient MSB and the
coefficient banks for Filter B will cor-
respond to the coefficient LSB; there-
fore, bit 2 must be set to 1.
Once again, to insure correct results,
the coefficient sets must be aligned
appropriately; that is to say, the MSB
coefficients must correspond to their
LSB coefficients. The output data will
appear at DOUT
at ROUT
any value. Bit 1 is set to 0 (for
single filter mode) and bit 0 is set to 0
be disabled). Therefore, to realize
24-bit data/12-bit coefficients the user
must write 008H to Configuration
Register 5; conversely, for 12-bit data/
24-bit coefficients the user must write
00CH to Configuration Register 5.
-12
before adding it to the Filter
3-0
/COUT
(cascade mode must
15-0
11-0
; output appearing
will not be of
The Double Wide Data/Coefficient
Mode is valid in the Matrix Multipli-
cation Mode; however, special consid-
erations must be observed when these
two modes are combined. The LF3320
must be configured for single filter
mode only, for a maximum (8x8)
matrix. In addition, the user must
disable the cascaded filter mode, the
accumulator access mode, and the
data reversal (Table 7). For additional
considerations, refer to the corre-
sponding mode of operation section.
Accumulator Access Mode
Accumulator access allows the user to
accumulate the Filter A output with
the Filter B output. Therefore, this
mode is only valid when the device
has been configured for dual filter
operation. To configure the device for
this mode, bit 1 and bit 5 must be set
to 1; bit 5 is the corresponding accu-
mulator access bit (Table 7). Writing
022H to Configuration Register 5 con-
figures the device to accumulate the
Filter A output with the Filter B
output. All remaining Configuration
Registers, 0 through 4 inclusive, will
depend on specific application
requirements (see Tables 2 through
4). In this mode of operation,
F
IGURE
DIN
11-0
11. A
12
CCUMULATOR
2-9
REGISTERS
DOUT
CIRCUIT
16
FILTER
R.S.L.
I/D
A
15-0
A
CCESS
Horizontal Digital Image Filter
the accumulated output is realized
at DOUT15-0. The output data at
ROUT15-0/COUT15-0 is the Filter B
output that is normally expected;
however, the accumulated output
data (DOUT15-0) will be delayed by
one clock cycle, compared to the Filter
B output data.
This type of operation is useful when
two filtered data streams (i.e. I+jQ)
need to be accumulated. Such is
the requirement to satisfy the equa-
tion, y(t) = cos(vt)+jsin(vt). The
complex data can be streamed and fil-
tered using a respective ‘I’ filter and
‘Q’ filter. To convert the complex
result into a real result, as seen at
the LF3320 output, two multiplies and
one accumulation is required. The
cosine and sine functions are realized
through the coefficient sets; conse-
quently, multiplied by the corre-
sponding ‘I’ and ‘Q’ data streams. To
satisfy the remainder of the equation,
Filter A and Filter B must be accumu-
lated.
As previously stated, this mode of
operation is only valid with the dual
filter mode configuration. All modes
of operation, that are valid in the
dual filter mode, are valid with the
accumulator access mode. For addi-
M
ODE
Video Imaging Products
ROUT
REGISTERS
CIRCUIT
16
3-0
FILTER
R.S.L.
I/D
B
/ COUT
11-0
6/22/2007–LDS.3320-R
12
LF3320
RIN
11-0