- Wed Dec 09, 2015 1:08 am
#36043
Not so simple. The current varies a lot while the module is active. Use a DSO to see pattern, where you can then measure the total power used in a given time. Connect a low value resistor between the power source ground and your board's ground and measure the voltage across it. No need for an "accurate" resistor as long as you can measure it accurately then use Ohm's law I=V/R. to correlate DSO V to board I.
The lower the resistor the better, but the measured voltage will also reduce so you select what your DSO can show reliably.
This will not work for deep sleep: 20uA across 1R gives 20uV, too low for most DSOs. You can use something like
uCurrent, not cheap but not a bad thing to have in your kit.
For now (esp deep sleep) you just use a DMM with a uA range (no resistor required), as many have these days.
For idle, at about 80mA (idle WiFi), a DSO with a 1R resistor is acceptable, as is the active WiFi with 300mA (or above) peaks.