LF3347 データシートの表示（PDF） - LOGIC Devices
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LF3347 Datasheet PDF : 10 Pages
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DEVICES INCORPORATED
LF3347
High-Speed Image Filter with Coefficient RAM
FUNCTIONAL DESCRIPTION
Coefficient Banks
The LF3347 has four coefficient banks
which feed coefficient values to the
multipliers. Each bank can store 256
12-bit coefficients. In the example
shown in Table 3, address 10 in coeffi-
cient banks 1 through 4 is loaded with
the following values: ABCH, 789H,
456H, 123H. The coefficient banks are
not written to until all four coefficients
have been loaded into the device.
A7-0 determines which coefficient set is
sent to the multipliers. A value of 0 on
A7-0 selects set 0. A value of 1 selects
set 1 and so on.
Rounding/Offset
The accumulator output may be rounded
before being sent to the output select
section. Rounding is user-selectable and
is accomplished by adding the contents of
a round register to the accumulator
output (see Figure 2). There are sixteen
32-bit round registers. In the example in
Table 4, round register 10 is loaded with
76543210H. A round register is not
written to until all four data values have
been loaded into the device.
registers. Each limit register contains both
an upper and lower limit value. The
lower limit is stored in bits 15-0 and the
upper limit is stored in bits 31-16. If the
value fed to the limiting circuitry is less
than the lower limit, the lower limit is
passed to the device output. If the value
fed to the limiting circuitry is greater than
the upper limit, the upper limit is passed
to the device output. When loading limit
values into the device, the upper limit must
be greater than the lower limit. In the
example shown in Table 4, limit register
15 is loaded with a lower limit of 0123H
and an upper limit of 7FEDH. A limit
register is not written to until all four data
values have been loaded into the device.
SELLMT3-0 determines which limit
register is used for limiting. A value of 0
on SELLMT3-0 selects limit register 0. A
value of 1 selects limit register 1 and so on.
TABLE 3. COEFFICIENT BANK LOADING FORMAT
CC11CC10 CC9 CC8 CC7 CC6 CC5 CC4 CC3 CC2 CC1 CC0
1st Word 0 0 0 0 0 0 0 0 1 0 1 0
Address
2nd Word 1 0 1 0 1 0 1 1 1 1 0 0
Bank 1
3rd Word 0 1 1 1 1 0 0 0 1 0 0 1
Bank 2
4th Word 0 1 0 0 0 1 0 1 0 1 1 0
Bank 3
5th Word 0 0 0 1 0 0 1 0 0 0 1 1
Bank 4
TABLE 4. ROUND REGISTER LOADING FORMAT
CC11CC10 CC9 CC8 CC7 CC6 CC5 CC4 CC3 CC2 CC1 CC0
1st Word 1 0 0 0 0 0 0 0 1 0 1 0
Address
2nd Word R R R R 0 0 0 1 0 0 0 *0
SELRND3-0 determines which round
register is used for rounding. A value of 0
on SELRND3-0 selects round register 0. A
value of 1 selects round register 1 and so
on. If rounding is not desired, a round
register should be loaded with 0 and
selected as the register for rounding.
Output Select
The filter output word width is 32-bits.
However, only 16-bits may be sent to the
device output. SHIFT4-0 determines
which 16 bits are passed to the device
output (See Table 1).
3rd Word R R R R 0 0 1 1 0 0 1 0
4th Word R R R R 0 1 0 1 0 1 0 0
5th Word R R R R **0 1 1 1 0 1 1 0
R = Reserved. Must be set to “0”.
* This bit represents the LSB of the Round Register.
** This bit represents the MSB of the Round Register.
TABLE 5. LIMIT REGISTER LOADING FORMAT
CC11CC10 CC9 CC8 CC7 CC6 CC5 CC4 CC3 CC2 CC1 CC0
1st Word 1 1 0 0 0 0 0 0 1 1 1 1
Address
2nd Word R R R R 0 0 1 0 0 0 1 1
Output Limiting
3rd Word R R R R *0 0 0 0 0 0 0 1
An output limiting function is provided
4th Word R R R R 1 1 1 0 1 1 0 1
for the output of the filter. When limiting is
enabled (LMTEN LOW), the limit register 5th Word R R R R **0 1 1 1 1 1 1 1
selected with SELLMT3-0 determines the
valid range of output values for the overall
filter. There are sixteen 32-bit limit
R = Reserved. Must be set to “0”.
* This bit represents the MSB of the Lower Limit Register.
** This bit represents the MSB of Upper Limit Register.
Video Imaging Products
4
08/16/2000–LDS.3347-G
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