I love this module so much! It is the upgrade version of the Adjustable Mini DC-DC Module. It integrated a volage meter with the DC-DC module – LM2596S, with this function, you can monitor your project much more easier. The voltage meter can measure the input voltage or output voltage, which is adjustable by the protentiometer, with a precision of ±0.1V.Note that the voltage meter would not work if the input voltage below 4V. Press the button to switch voltage to measure, between the input voltage and output voltage. There are also 2 LEDs (IN and OUT) to indicate which voltage is measuring by the voltage meter. You can also close the voltage meter by long pressing the button (1S< press time < 4S), after you releasing the button, the voltage meter would be close. This module can be also calibrated manually as following method:

1. Power up the module with a stable and accurate power supply , such as a 5V power supply, and long pressing (press time > 4S) the button makes the module enter the calibration model, after releasing the button, the related LED would light up to indicate which voltage is now calibrating, and the numeric display blinks the correction value.(Default: 0.0V)

2. Short press the botton to change the correction value(-0.5V ~ 0.5V), for example, if your power supply is 5V, but the result of voltage meter is 4.8, you need to set the correction value to +0.2V.

3. Long press (press time ≈ 2S), to store the input voltage correction value, the module will enter the output voltage correction value calibration model automatically.

4. Calibrate the output voltage in the same way above; The correction value will be stored in nonvolatile memory.