An IP block will tend to have an average power consumption in each of its phases or modes.
Power modes include sleep, idle, off, on etc..
Clock frequency and supply voltage are also subject to step changes and expand the discrete phase/mode operating space.
Given that blocks switch between energy states a simple energy estimation technique is based percentage of time in each state.
This was how the TLM POWER2 library for SystemC worked. TLM POWER3 uses this approach for static power but logs energy quanta for each transaction.
The Parallella board has two USB line drivers (circled in red). They have three operating modes with different energy use in each.
| 43: (C) 2008-17, DJ Greaves, University of Cambridge, Computer Laboratory. |