Dear community,

I am trying to measure the power consumption of an embedded system versus that of the Raspberry Pi.
The embedded system is attached to a development kit which provides two measurement pins.
One can attach a multimeter to these two measurement pins and view the current draw.



However, the Raspberry Pi 3B does not have such measurement pins.
I know the existance of these 'USB power meters' (See the figure below), but I am not too sure about measurement qualities.

What would be an elegant and accurate way to measure power consumption?

With kind regards,
Youri.

 

Welcome to AAC!

The device you referenced can't provide information regarding power usage unless it has a data logging capability.

Regarding accuracy, don't buy a cheap one. I bought one on AliExpress and the current readings are definitely not accurate. Fortunately, it only cost a dollar or two.

If it were me, I'd collect current and voltage data (or just current if it wasn't being operated from a battery) over a period of time and calculate power usage.

 

From our friends at WIKI.

An embedded system is a programmed controlled and operating system 'RTOS' with a dedicated function within a larger mechanical or electrical system, often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts.

Enter the problem. Any system, which includes an operating system and is doing something will consume power based on what it is doing at any point in time. This is unlike measuring the power consumed for example by a 100 Watt incandescent light bulb which would be 0.1 kilowatt hour. As a processor and any peripherals perform a task they will use varying amounts of power based on the task they are performing so over any given period of time the power consumed will depend on how much work is done.

The only way to get a rough idea of power consumed is as dl324 mentions. You would data log the voltage and current at a sample rate over a period of time, for example 1 sample per second and then draw an average and knowing what an embedded system was doing during that time period. You also need to know what, if any peripherals were enabled or disabled.

The USB device you linked to will provide you with the voltage and the current but will not do the logging over time. So you need an accurate means to collect the data which will also log the data and do the basic math functions. All of which is very doable but comes at a cost.

Ron

 

Thank you very much for your replies, you both.
I did a little bit of research and the EL-USB-ACT seems good to do measurements with for the Raspberry Pi

With kind regards,
Youri.