An oscilloscope can be used to measure the current over a given or continuous time
interval and to capture the current profile.
Complete the following steps to measure the current
profile of the nRF9161 DK:
-
Solder a 0.5 Ω resistor to R97.
-
Set the oscilloscope to differential mode or to a mode that is similar.
-
Connect the oscilloscope using two probes on the pins of the P22
connector.
-
Calculate or plot the instantaneous current from the voltage drop across the
0.5 Ω resistor by taking the difference of the voltages measured on the two
probes.
The voltage drop is proportional to the current.
-
Measure the voltage drop over the 0.5 Ω resistor to get the current power
profile.
The plotted voltage drop can be used to calculate the current at a given point
in time. The current can then be averaged or integrated to analyze current and
energy consumption over a period.
Figure 1. Current measurement with an oscilloscope
To reduce noise, do the following:
- Use probes with 1x attenuation.
- Enable averaging mode to reduce random noise.
- Enable high resolution function if available.
A minimum of one sample every 5 µs is needed to accurately measure the average
current.
