For various projects in the scope of sensor networks it is often necessary to benchmark their performance in terms of energy consumption and computing performance. Measuring energy consumption with a osciloscope can be cumbersome. Sensor nodes operate on low currents. Usually a shunt resitor is used to transform current to a voltage that then can be measured. However a current consumption in the µA range will only lead to a small voltage drop. It must be amplified by using an operational amplifier (Op-Amp).
We have implemented such a setup as a Arduino shield. It allows a replacement of the shunt resistor dependent on the current range that is measured. Current induced voltage and supply voltage are sampled by an Arduino and logged to serial output for further analysis. Figure 2 shows the PCB design in Eagle.
And Figure 3 shows the final working Arduino shield based on this design.