Each LUT has three inputs and one truth table. This allows implementation of logic functions with up to three inputs and one output; with the unused inputs that can be tied low (masked).
The truth table for the desired combinational logic expression is defined by the bits in the LUTn Truth Table (CCL.TRUTHn) registers. Each combination of the input bits corresponds to one bit in this register.
| LUTn-TRUTHSEL[2] | LUTn-TRUTHSEL[1] | LUTn-TRUTHSEL[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] |