What power profiling tools do you use and how do they compare?

The three most common power profiling tools in embedded development each target different measurement needs and budgets:

Nordic Power Profiler Kit II (PPK2) is the best value option at around $100. It measures current from 200 nA to 1 A with a dynamic range that covers both deep sleep and active radio transmission. It operates in two modes: source mode (PPK2 supplies power to the DUT at a configurable voltage from 0.8V to 5.0V) and ampere meter mode (inline measurement with an external supply). The companion nRF Connect Power Profiler software provides real-time current visualization, average/peak statistics, and supports GPIO trigger lines to correlate current draw with firmware events. The main limitation is its sampling rate — approximately 100 kHz — which may miss very fast transients (sub-10 microsecond current spikes during flash writes or radio calibration).

Joulescope (JS110/JS220) is a professional-grade power analyzer priced around $500-1000. It offers a wider dynamic range (nanoamps to amps), higher bandwidth, and more precise measurements than the PPK2. The JS220 supports continuous streaming at 2 Msps (megasamples per second) with 18-bit resolution, capturing even the fastest current transients. Its software supports multi-channel correlation, energy accumulation, and scripting for automated test campaigns. Joulescope is the tool of choice when you need to accurately characterize energy-per-operation metrics (energy per radio TX packet, energy per sensor read) for precise battery life calculations. The downside is cost and the fact that it is measurement-only — it does not supply power, so you need a separate low-noise bench supply.

Shunt resistor with oscilloscope is the zero-cost baseline approach that every embedded engineer should know. A 10-ohm resistor in the power line converts current to voltage, which an oscilloscope displays as a time-domain waveform. This approach has the highest bandwidth (limited only by your oscilloscope), costs nothing beyond equipment most labs already have, and provides immediate visual feedback. The drawbacks are poor dynamic range (a single shunt value cannot simultaneously resolve 1 microamp sleep current and 100 mA active current without either saturating the ADC or losing the small signal in noise) and the voltage drop across the shunt perturbing the DUT's supply. For quick checks and debugging, it remains indispensable — especially when you need to correlate current waveforms with SPI traffic or GPIO events captured on other oscilloscope channels simultaneously.