Saturday, November 5, 2011

Rearrange Blocks in PlanAhead Schematic Viewer

The Schematic Viewer in PlanAhead is an invaluable tool to help understand and analyze synthesized netlists. PlanAhead 13.3 added a nice feature that allows users to move blocks around in the Schematic Viewer. Users can easily rearrange the schematic to follow the control/data flow or specific structure the design was intended for so they can better visualize the logic as well as use it for documentation purse.

To move a block in the Schematic Viewer, simply hold down the SHIFT key and then use the left mouse button (LMB) to select and drag&drop the block to the new location. Connections between blocks will be redrawn for the new layout.

The two snapshots below are schematics of the ternary adder circuit before and after rearrangement. The second snapshot clearly shows the regular structure of the circuit that the LUT3/LUT4 pair for each bit share common inputs and can be packed into the same LUT6_2.

Schematic before rearrangement

Schematic After Rearrangement 


  1. Nice! How come our FAE didn't show us that. We love PlanAhead.

  2. Nice to see a decent schematic view in a Xilinx product. However, for those with deeper pockets the Synplify schematic viewer is still the best.

  3. @Bret, what are the features you like in Synplify but are missing in PlanAhead? I can pass them along if you can share your thoughts.