Inspired by Nick Gammon's comprehensive writeup on low-power methods (http://www.gammon.com.au/power), I'm now trying to create a barebones Arduino with extremely low-power consumption.
I'm starting with a minimal Atmega328-based setup on stripboard, powered by a Li-ion battery. I want to measure the current draw of the circuit load each time I change something.
QUESTION: What are some methods of measuring the current draw with high PRECISION, ideally with around 1 uA (one microamp) resolution?
I'd prefer to use standard electronics tools: DMM, or oscilloscope, or resistors, etc. But otherwise, pretty flexible on the method since I am measuring draw of entire circuit load (e.g., measured in series with the battery+), as opposed to just a specific part.