The vibrations index and knocks counter are both powered by the built-in accelerometer.
The vibration index measures the actual intensity of any vibrations. In other words, how strong is the vibration/movement.
The knocks counter works a bit differently. Knocks are analysed from the raw vibration data (accelerometer). It records when the device senses a sudden vibration or knock. The firmware can distinguish between a single knock or a double knock.
For example, If you place the device on a stable and flat surface, using your hand or other object to hit the surrounding surface, the device can detect such event from the raw vibration data. Vibration index is sampled at most one record every second.
Deploy the device on your door or window. Every time the door/window opened or closed can be detected.
Place the device close to an equipment motor, it can help to monitor if the motor is working or stops.
The vibration perception threshold ranges from 5 to 255. The smaller the value is, the greater the sensitivity the sensor will be.
Please note: the vibration sensor consumes a lot of power. Once enabled, the power consumption will increase at least 40%. Please enable it according to your need and plug the device with USB power supply when using it.