This is an alarm inserted into the ground whose function is to notify you to water the plants. It makes alarm when the sensor detects a low level of moisture in the soil, telling you it is time to water the plants.
A common problem for your garden is to remember to water the plants, but now with this alarm module for watering plants, it is no longer an issue.
It is a very easy to use module that detects presence or absence of moisture in the ground and when it comes back to the point "dry" ACST will start beeping, reminding you to water your plants.
That's just the basic function of the module. You can connect to the I2C and interact with it as you wish. Let your imagination free and create new gardening hacks.