The idea of this project starts from the observation of the methods of sorting in our country. In fact, citizens are provided with a card assigned by the city hall to access to the waste sorting stations, with the card the citizens open the selected bins. We have noticed that there is no signaling device which indicates to the user the filling state of the containers, therefore we often find ourselves having to do all the operations uselessly, because the bins are full. We have invented this system which allows the citizens to view the filling state of the bins, through a microcontroller, a sensor and LED. The microcontroller used is an Arduino, equipped with a programmable microprocessor using specific software. The Arduino receives the input from the ultrasonic sensor and outputs a signal that allows the LED to turn on. The ultrasonic sensor is formed by an emitter cell, that emits an ultrasonic wave which, with the impact with an object, the signal returns to the receiver cell. The function of the microcontroller is to convert the signal emitted by the sensor into a distance measurement. The Arduino has been programmed so that it can work in a specific range and, once the converted value reaches the reference value, one of the three LED is lit in the output: green when the container is empty, yellow when the container is medium capacity and red when the container is full. The system created by us is also equipped with a bluetooth module which allows you to have the mapping of the waste sorting stations with the relative information on the filling state sorting on a special mobile APP.