DEVICES INCORPORATED

LF3321

Horizontal Digital Image Filter

Improved Performance

LOGIC Devices Incorporated

19

Feb 5, 2003 LDS.3321-A

Video Imaging Products

The LF3321 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 LF3321 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 Multiplication Mode; however, special

considerations must be observed when these two modes are combined. The LF3321 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 corresponding mode of operation section.

Operating Modes

Double Wide

Data/Coefficient

Mode

Figure 20. Single Filter, Matrix Multiply Timing Sequence

CLK

CENA / CENB

1

2

DATA SET 0

3

SHENA / SHENB

*

11 Clocks - First Output of First Data/Coefficient Set

**

16 Clocks - End of First Data/Coefficient Set

***

26 Clocks - Final Output of First Data/Coefficient Set

1 Data Set with 16 Coefficient Sets

DATA SET 0

OUT0

OUT1

11*

12

13

14

16**

OUT15

26***

OUT2

OUT3

OUT4

OUT5

OUT6

15

17

TXFRA/ TXFRB