Allegro – Tip of the week: Forcing the name of an XNet

When grouping nets to create an XNet, there is an internal algorithm that determines the name of extended nets(XNET) automatically. This algorithm uses the following criteria (in a hierarchical order):  

1. A net that is higher in the design hierarchy is selected. 

1. If both nets have zero driver pins, the one with non-zero receiver pins is selected. 

1. If both nets have zero driver pins and non-zero receiver pins, the one with the least number of receiver pins is selected. 

1. If one has zero driver pins and the other has non-zero receiver pins, the one with zero driver pins is selected. 

1. If no net is selected yet, the one that comes first, lexicographically, is selected. 

 However, there is a way to bypass this algorithm and force the name of the XNet. If you attach the CDS_XNET_NAME property to a net, you will force this net name to the XNet level.  

Configure it as follows:  

In this example, after following these steps, you will ensure that the XNet name is N852308.  

Have you used XNet or net properties that you found particularly useful for a design? Share your experience with the community and let us learn from each other.