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LF48908QC31

Two Dimensional Convolver

LOGIC Devices 

DEVICES INCORPORATED

LF48908

Two Dimensional Convolver

be ignored. If the LF48908 is not in

active operation or if the innactive

Coefficient Register is being written to

during active operation.

Cascade Operation

The Cascade Input lines (CASI15-0)

and Cascade Output lines (CASO7-0)

are used to allow convolutions of

kernel sizes larger than 3 x 3. The

Cascade Input lines are also used to

allow convolutions on row lengths

longer than 1024 pixels. The Cascade

Mode Bit (Bit 0) of the Initialization

Register determines the function of

the Cascade Input lines. If the Cas-

cade Mode Bit is a “0”, then the

Cascade Input lines are to be used to

cascade multiple LF48908s together to

perform convolutions of larger kernel

sizes. CASI15-0 will be left shifted (by

an amount determined by bits 7 and 8

of the Initialization Register) and then

added to DOUT19-0. Cascading is

accomplished by connecting CASO7-0

and DOUT19-0 of one LF48908 to

DIN7-0 and CASI15-0 respectively of

another LF48908. If the Cascade

Mode Bit is a “1”, then the Cascade

Input lines are to be used with exter-

nal row buffers to allow for longer

row lengths. In this mode, the Cas-

cade Input lines are split into two 8-bit

data busses (CASI15-8 and CASI7-0)

which are fed directly into the multi-

plier array.

TABLE 3. INITIALIZATION REGISTER

BIT

FUNCTION

0

CASCADE MODE

0 Multiplier input from internal row buffers

1 Multiplier input from external buffers

21

INPUT DATA DELAY

0 0 No data delay registers used

0 1 One data delay register used

1 0 Two data delay registers used

1 1 Three data delay registers used

3

INPUT DATA FORMAT

0 Unsigned integer format

1 Two’s complement format

4

COEFFICIENT DATA FORMAT

0 Unsigned integer format

1 Two’s complement format

65

OUTPUT ROUNDING

0 0 No rounding

0 1 Round to 16 bits (i.e. DOUT19-4)

1 0 Round to 8 bits (i.e. DOUT19-12)

1 1 Not valid

87

CASI15-0 INPUT SHIFT

0 0 No shift

0 1 Shift CASI15-0 left two

1 0 Shift CASI15-0 left four

1 1 Shift CASI15-0 left eight

TABLE 4. CONTROL LOGIC

ADDRESS MAP

A2-0

FUNCTION

000 Load Row Buffer Length

Register

1

001 Load ALU Microcode Register

010 Load Coefficient Register 0

2

011 Load Coefficient Register 1

100 Load Initialization Register

101 Select Coefficient Register 0

3

for Internal Processing

110 Select Coefficient Register 1

for Internal Processing

4

111 No Operation

5

6

7

8

9

10

11

Video Imaging Products

7

08/9/2000–LDS.48908-J

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