This uses Arduino MEGA connected to a Ultrasonic sensor and and I2C LCD screen to display distance from the sensor This code will check distance and indicate if an obstacle/person is away for 5 ...

#As you could see in this image the Arduino UNO is connected to the Ultrasonic Sensor as well as Bread Board. #Arduino's Digital pins are connected to the Bread board ...

This is a very simple digital distance meter, which you can add to your water-level indicator circuit to show water level ... It is built around Arduino Uno board, HC-SR04 ultrasonic sensor, Nokia ...