Is it possible to measure (with software, like PowerTOP) the Pi's current power consumption, on my Raspberry Pi?
No. You cannot accurately measure the power consumption of your Raspberry Pi by just software. There needs to be some hardware in place in order to do this and devices rarely have this by default.
The easiest option would be to use a wall outlet power meter or usage monitor. You can buy these for $10-$20 at a local store.
Without such hardware, the best you can get are estimations.
Your best bet is to use a USB voltmeter/ammeter between your USB power source and the Pi.
In addition, you will require:
- a USB micro to USB 'A' convertor from the power source to the USB voltmeter;
- a USB 'A' to USB micro cable from the USB voltmeter to the Pi.
There are many different types ranging from $1 to $5, depending if you want a single display, a dual display, as pictured, or up to a quad display that also shows power (Watts) and charge (Coulombs)
Whilst you can't directly monitor the power consumption you can obtain information about the operating voltage of the:
sdram_p (see here for more details).
vcgencmd measure_volts <id>
e.g. To check the core voltage:
pi$ vcgencmd measure_volts volt=1.2000V
Use a multimeter in series with a bench top power supply, or look at the bench power supply itself if it has a built-in ammeter.
Measuring the whole setup (with power supply) won't give you an accurate reading of the Raspberry Pi's actual usage since you will also be measuring inefficiencies in the power supply you use.