I have an RF mcu intended to run on a coin cell and I'm going to need to measure current consumption as it transitions from state to state.
As a quick test I put a 2 ohm resistor in series with the circuit and attached that to the oscilloscope with the probe on one side of the resistor and he probe ground on the other side of the resistor. Here is what I'm getting on the oscilloscope:
What is curious is how the current appears to flow back wards as much as it went forwards. I assume my test setup is bad, and I either need isolation somewhere or I need to implement a differential probe.
Is this normal and expected, or do I need to resolve some issues before trying to use this for measuring current consumption?
Note that the processor is running at 24MHz which closely matches the pulses in the waveform.
Here is the test setup: