The truth table in each LUT unit can generate a combinational logic output as a function of up to three inputs (IN[2:0]). The unused inputs can be turned off (tied low). The truth table for the combinational logic expression is defined by the bits in the CCL.TRUTHn registers. Each combination of the input bits (IN[2:0]) corresponds to one bit in the TRUTHn register, as shown in the table below.
Figure 1. Truth Table
Output Value Selection of a LUT
| IN[2] | IN[1] | IN[0] | OUT |
|---|---|---|---|
0 |
0 |
0 |
TRUTH[0] |
0 |
0 |
1 |
TRUTH[1] |
0 |
1 |
0 |
TRUTH[2] |
0 |
1 |
1 |
TRUTH[3] |
1 |
0 |
0 |
TRUTH[4] |
1 |
0 |
1 |
TRUTH[5] |
1 |
1 |
0 |
TRUTH[6] |
1 |
1 |
1 |
TRUTH[7] |