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Cadence Low Power Flow (Power Domains creation and Power Estimation problems)

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Nef

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Dear all,

I am studying the Cadence low power flow, and I would need your help with some issues.

1. I have written a Common Power Format -CPF- file (version 1.1) with 14 Power Domains. Each switchable PD is created as follows:
create_power_domain -name PD* -instances {***}\
-shutoff_condition {***} -base_domains {***}
Then I have created a Design in SoC Encounter (v14.13) and executed the loadCPF and commitCPF commands.
These commands are executed without any error, and isolation and state retention instances are added to the PDs.

However at the end, three warnings arise:
**WARN: (ENCFP-3910): Power domain 'PD2' is out of die box. Cannot create rows for this power domain.
**WARN: (ENCFP-3910): Power domain 'PD5' is out of die box. Cannot create rows for this power domain.
**WARN: (ENCFP-3910): Power domain 'PD9' is out of die box. Cannot create rows for this power domain.

These three PDs differs from the others just in the number of instances. PD2, PD5 and PD9 have only one instance.
If I reduce the instances, to one, of the generic PDx, I'll have also the warning:
**WARN: (ENCFP-3910): Power domain 'PDx' is out of die box. Cannot create rows for this power domain.

I haven't ever read any rule about the number of instances in a PD. And I hadn't these warnings with a previous version of SoC Encounter (v11.12).
Have anyone ever had alike warnings?


2. I would like to estimate power consumption of my design.
Normally I synthesize the rtl, simulate the netlist, generate a switching activity VCD file, and I run a RC script which reads the netlist, reads the VCD and generates the power report.
But in this case my script can't work, because the commitCPF command doesn't add any power switches to the netlist. Thus RC doesn't know which part of the design should be off, even if I generated the VCD by simulating netlist + CPF.
I have modified my script, which now reads netlist, CPF, VCD and then generates the power report.
In this way the estimated power decreases, but I haven't ever read a guide with such a power estimation method, and I'm not sure the power in the report is correct.

There is a "correct" method to estimate the power consumption of a low power design?

Thanks for your help :)
Nef
 

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