4 The Fitting Process Flow

The fitter is a complex place-and-route software program that implements multiple options to fit a design into ATF15XX/ATF1500 devices. These options can be user-controlled or automatically selected by the fitter. For information on the number of design‑pass iterations performed before the fitter determines whether a design can be successfully fit, refer to the sections Design Passes, Design Rule Check and Assign Global Input Pins. The fitting process is outlined in Figure 4-1.