4.5 Control Signal Patching

Control Signal Patching is performed when a design has multiple product term flip-flop clocks, clock enables, resets, presets or output enable logic. In this process, the fitter creates foldback or buried feedback nodes to map these inputs into the ATF15XX/ATF1500 device. This process is necessary because each ATF15XX/ATF1500 macrocell has only one product term for each of these inputs.