OpenROAD is an open-source, integrated system for chip design and optimization. It includes a graphical user interface (GUI) that enables designers to visualize and analyze the critical phases of chip design, such as placement congestion, clock tree synthesis (CTS), and timing reports. In this blog, we will appreciate the OpenROAD GUI features for analyzing these critical phases of chip design.

Launch the GUI with All the Values 
To launch the OpenROAD GUI, you can either type "openroad" or "openroad -gui" in the command prompt. The latter will directly start the GUI. Once you have launched the GUI, you can use the "Open file" option to open the design database (DB). In the results directory, you can find the final floorplan file, which you can load.

Enable Heat Maps for Placement and Routing Congestion 
During each stage of the flow, you can enable specific heat maps to check the density of the standard cells' placement. There are two important stages: placement and the final stage before detailed routing. You can also check the routing congestion using the "route" command for global and detailed routing. You can then view the detailed routing GUI.

Check for Hotspots and Reduce Congestion 
By analyzing the heat maps, you can check for hotspots and reduce congestion before proceeding to CTS and routing stages. If there are any hotspots, you can reduce the congestion and rerun the flow to check if there are any more hotspots. You can also check the congestion reports and heat maps and enable/disable the options you want to include during placement.

View Legend and Density Ratio 
To better understand the congestion, you can view the legend that shows the density ratio. The blue color represents the lowest congestion, and the dark red color represents the highest congestion range.

Analyze Timing Reports 
In addition to analyzing placement and routing congestion, the OpenROAD GUI also enables designers to analyze timing reports. The timing report includes the core clock, required time, arrival time, slack, and start and end points. You can view the timing report for the whole design and analyze specific paths with all the data path details.

Conclusion 
The OpenROAD GUI is a powerful tool for chip designers that enables them to visualize and analyze critical phases of chip design such as placement congestion, CTS, and timing reports. The GUI allows designers to check for hotspots and reduce congestion, view legends and density ratios, and analyze timing reports for the whole design and specific paths. Overall, the OpenROAD GUI is an essential tool for chip designers that can help them optimize their designs and improve the performance of their chips.