Tuesday, 13 September 2016

What is location fanout in UPF ?

Certain UPF command has -location switch . i.e set_isolation , set_level_shifter . Again -location can be "fanout".

Consider a below example to understand that how isolation cell will be inserted/placed by synthesis tool when -location fanout is specified .

Here domain PD1 domain o/p signal is going to two different domain PD2 and PD3 .So this is a case of fanout .

Now if user has isolation strategy on PD1 domain with -location fanout , Isolation cell will be inserted as shown in figure under Netlist option (named as ISO) .


UPF:

set_isolation iso_1 -domain PD1 -applies_to outputs -location fanout


RTL:






Netlist:



6 comments:

  1. I think in the description the location should be fanout instead of self .

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  2. Thanks Pankaj I have made the change.

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  3. can you please explain the difference between add_power_state and add_port_state in upf?

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  4. add_power_state was introduced in upf2.0. Basically it can refer to supply set . Most of the initial level UPF are based on supply set instead of supply net as the information related to supply net is not available initially in design phase.

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  5. This comment has been removed by the author.

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  6. can you please provide information on different location options (parent,self,fanout,sibling..) related to ISOALTION.

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