As your design flow progresses through synthesis and implementation, you must regularly monitor and verify the power consumption to be sure that thermal dissipation remains within budget, that the board voltage regulators remain within their current operating limits and the design stays within any system power limits. You can then take prompt remedial actions if the power approaches your budget too closely.
Specify a power budget to report the power margin using the XDC constraint:
set_operating_conditions -design_power_budget <value in watts>
This value is used by the
command. The difference between the calculated on-chip power and the power budget is the
power margin, which is displayed in red in the Vivado
IDE if the power budget is exceeded. This makes it easier to monitor power consumption
throughout the flow.
The accuracy of the power estimates varies depending on the design stage
when the power is estimated. To estimate power post-synthesis through implementation,
report_power command, or open the Power Report
in the Vivado IDE.
- Post Synthesis
- The netlist is mapped to the actual resources available in the target device.
- Post Placement
- The netlist components are placed into the actual device
resources. With this packing information, the final logic resource count and
configuration becomes available. This
accurate data can be exported to the XPE spreadsheet.
allows you to:
- Perform what-if analysis in XPE.
- Provide the basis for accurately filling in the spreadsheet for future designs with similar characteristics.
- Post Routing
- After routing is complete all the details about routing resources used and exact timing information for each path in the design are defined.
In addition to verifying the implemented circuit functionality under best and worst case logic and routing delays, the simulator can also report the exact activity of internal nodes and include glitching. Power analysis at this level provides the most accurate power estimation before you actually measure power on your prototype board.