Code:
cat /usr/doc/powertop-2.1/README
Calibrating & Power Numbers
---------------------------
PowerTOP will, when running on battery, track your power consumption as well
as your activity on the system. Once there are sufficient such measurements,
PowerTOP can start to report power estimates for various activities.
You can help get this estimation more accurate by running a calibration
cycle:
powertop --calibrate
at least once; this will cycle through various display brightness levels
(including "off") as well as USB device activities and some other workloads.
Extech Power Analyzer / Datalogger support
------------------------------------------
I use, and our analysis teams use, the Extech Power Analyzer/Datalogger
(model number 380803) quite a lot, and PowerTOP supports using this
device over the serial cable. Just pass the device node on the command line
like this
powertop --extech=/dev/ttyUSB0
(where ttyUSB0 is the devicenode of the serial-to-usb adapter on my system)