LF3320 查看數據表（PDF） - LOGIC Devices Incorporated

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LF3320

Horizontal Digital Image Filter

LOGIC Devices Incorporated 

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LF3320

Horizontal Digital Image Filter

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 2-12 before adding it to the Filter 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 coefficient banks

for Filter A will correspond to the

coefficient MSB and the coefficient

banks for Filter B will correspond to

the coefficient LSB; therefore, 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 DOUT15-0; output appearing

at ROUT3-0/COUT11-0 will not be of

any value. Bit 1 is set to 0 (for single

filter mode) and bit 0 is set to 0

(cascade mode must 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.

The Double Wide Data/Coefficient

Mode is valid in the Matrix Multiplica-

tion Mode; however, special consider-

ations 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

FIGURE 11. ACCUMULATOR ACCESS MODE

12

DIN11-0

I/D

REGISTERS

I/D

REGISTERS

12

RIN11-0

FILTER

A

FILTER

B

R.S.L.

CIRCUIT

16

DOUT15-0

R.S.L.

CIRCUIT

16

ROUT3-0 / COUT11-0

reversal (Table 7). For additional

considerations, refer to the correspond-

ing 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 accumulator access bit

(Table 7). Writing 022H to Configura-

tion Register 5 configures the device to

accumulate the Filter A output with the

Filter B output. All remaining Configu-

ration Registers, 0 through 4 inclusive,

will depend on specific application

requirements (see Tables 2 through 4).

In this mode of operation, the accumu-

lated 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 equation,

y(t) = cos(vt)+jsin(vt). The complex

data can be streamed and filtered

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 accu-

mulation is required. The cosine and

sine functions are realized through the

coefficient sets; consequently, multi-

plied by the corresponding ‘I’ and ‘Q’

data streams. To satisfy the remainder

of the equation, Filter A and Filter B

must be accumulated.

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 accumu-

lator access mode. For additional

considerations, refer to the correspond-

ing mode of operation section.

FUNCTIONAL DESCRIPTION

ALUs

The ALUs double the number of filter

taps available, when symmetric

coefficient sets are used, by pre-adding

data values which are then multiplied

by a common coefficient (see Figure 12).

Video Imaging Products

2-9

08/16/2000–LDS.3320-N

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