nRF52 DK v1.1.x

Using an oscilloscope for current profile measurement

Follow the step by step instructions below to measure the current using an oscilloscope.

  1. Make sure you have prepared the development kit board as described in Preparing the development kit board.
  2. Mount a 10 Ω resistor on the footprint for R6.
  3. Connect an oscilloscope in differential mode or similar with two probes on the pins of the P22 connector as shown in Figure 1.
  4. Calculate or plot the instantaneous current from the voltage drop across the 10 Ω resistor by taking the difference of the voltages measured on the 2 probes. The voltage drop will be proportional to the current. The 10 Ω resistor will cause a 10 mV drop for each 1 mA drawn by the circuit being measured.
  5. The plotted voltage drop can be used to calculate the current at a given point in time, calculate average current over a period, or integrated to calculate the energy used over a period.
Some tips to reduce noise:

Use minimum 200 kSa/s (one sample every 5 µs) to be able to get the correct average current measurement.

Figure 1. Current measurement with oscilloscope

Documentation feedback | Developer Zone | Subscribe | Updated 2017-04-21