
Data Sheet
February 1997
ATT3000 Series Field-Programmable Gate Arrays
8
Lucent Technologies Inc.
Configurable Logic Block
(continued)
5A. Combinatorial Logic Option 1
generates two functions of four
variables each. One variable, A, must be common to both func-
tions. The second and third variables can be any choice among
B, C, Qx, and Qy. The fourth variable can be either D or E.
5B. Combinatorial Logic Option 2
generates any function of five
variables: A, D, E, and two choices among B, C, Qx, Qy.
5C. Combinatorial Logic Option 3
allows variable E to select
between two functions of four variables: both have common
inputs, A and D, and any choice among B, C, Qx, and Qy for
the remaining two variables. Option 3 can then implement
some functions of six or seven variables.
Figure 5. Combinatorial Logic Diagram
Figure 6 shows a modulo 8 binary counter with parallel
enable. It uses one CLB of each type. The partial func-
tions of six or seven variables are implemented by
using the input variable (.e) to dynamically select
the two functions of four variables each, the indepen-
dent results (F and G) may be used as data inputs to
either flip-flop or logic block output. For the single func-
tion of five variables and merged functions of six or
seven variables, the F and G outputs are identical.
Symmetry of the F and G functions and the flip-flops
allows the interchange of CLB outputs to optimize
routing efficiencies of the networks interconnecting
the logic and IOBs.
Figure 6. C8BCP Macro
A
B
C
D
E
QX
QY
ANY FUNCTION
OF UP TO 4
VARIABLES
F
ANY FUNCTION
OF UP TO 4
VARIABLES
G
QY
QX
A
B
C
D
E
ANY FUNCTION
OF 5
VARIABLES
A
B
C
D
E
QX
QY
F
G
A
B
C
D
QX
QY
A
B
C
D
E
QX
QY
F
G
ANY FUNCTION
OF UP TO 4
VARIABLES
ANY FUNCTION
OF UP TO 4
VARIABLES
M
U
X
5A
5B
5C
5-3104(F)
CLOCK
ENABLE
PARALLEL
ENABLE
CLOCK
COUNT
D0
Q0
D
Q
Q1
D1
D2
Q2
D
Q
FUNCTION OF 6 VARIABLES
D
Q
FUNCTION OF 5 VARIABLES
DUAL FUNCTION OF
4 VARIABLES
5-3105(F)