DEVICES INCORPORATED

LF3321

Horizontal Digital Image Filter

Improved Performance

LOGIC Devices Incorporated

6

Feb 5, 2003 LDS.3321-A

Video Imaging Products

When data reversal is enabled, the circuitry uses a pair of LIFOs to reverse the order of the data sent

to the reverse data path. TXFRA and TXFRB control the LIFOs in Filters A and B respectively. When

TXFRA/TXFRB goes LOW, the LIFO sending data to the reverse data path becomes the LIFO receiving

data from the forward data path, and the LIFO receiving data from the forward data path becomes the LIFO

sending data to the reverse data path.

The device must see a HIGH to LOW transition of TXFRA/TXFR B in order to switch LIFOs. If decimating by

N, TXFRA/TXFRB should go LOW once every N clock cycles. When data reversal is disabled, the circuitry

functions like an I/D Register. When feeding interleaved data through the filter, data reversal should be

disabled. Bit 6 of Configuration Register 1 and Configuration Register 3 enables or disables data reversal

for Filters A and B respectively.

Functional Description

Data Reversal

Continued

Figure 7 .Filter A and Filter B Round/Limit/Select Circuitry

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32

4

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4

RND

LIMIT

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16

RND

LIMIT

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16

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16

FILTER B RSL

FILTER A RSL

DATA IN

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DATA IN

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DATA OUT

DATA OUT

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5

SELECT

SELECT