Why we need adjustable delay? The v1495 mezzanine card (A395A) have a signal transmission time about 6ns. But we need all the signals go into the look up table at the same time. 6ns delay
How to solve it? Signal going to the A,B port Signal going to the D,E port A,B D,E 1 A,B D,E 2 A,B D,E 3 6ns
Input flip-flop 371MHz (now 350) signal D flip-flop signal Mode 7 counter Decoder Multiplexer data D flip-flop w/ enable Decoder Multiplexer DFFE
DFF1 Last page DFF2 LV1 LUT LV3 LUT LV2 LUT LV4 LUT LV5 LUT DFF Output Flip- flop 53MHz
Some Estimate The delay from input to output is about (9x18.86=169.74)+?? ns. The worst case, each channel from input to LUT part cost about 25 logic elements. Memory space only need 2048 bits.