You can deassert all the resets in the design. This option allows you to match the power number from tools much closely with the hardware number. You will have the option to enable/disable this option from the report power tool or in Tcl mode. There are three options for setting the Switching Activity for Resets:
- None
- This is the default mode. In this mode, the report power tool will not set any value and leave the activities as comes after vector-less propagation.
- Deassert
- When you select this option, the report power tool will deassert all the resets in the design.
- Do Not Deassert
- In this mode, changes of deassert option will be reverted back to original value.
Figure 1. Deassertion of Resets
The following Tcl options are introduced in set_switching_activity
and reset_switching_activity commands:
set_switching_activity -deassert_resetsThis is equivalent to Deassert option for Switching Activity for Resets.
reset_switching_activity -no_deassert_resetsThis is equivalent to Do Not Deassert option for Switching Activity for Resets. The Deassert option will not be set in the following exceptional conditions:
- If a reset net is connected to pins of different polarity. For example, if a reset net is connected to both the active-High reset pin and active-Low reset pin, then the command would not try to set value on this net.
- If a net connected to active-High reset pin is also connected to an active-High enable pin at the same time, then this command does not do anything.
- Nets connected with synchronizer circuits which provide an asynchronous clear and synchronous deassert functionality to avoid meta-stability issue crossing different clock domains.