Ultrasonic Sensor (HC-SR04) + Arduino
The HC-SR04 ultrasonic distance sensor uses sonar to determine distance to an object with stable readings and high accuracy of 3mm. The module includes ultrasonic transmitter, receiver and control circuit. It basic principles of work are outlined here if interested. One of the outstanding features of this distance sensor is that it can detect not only the distance between itself to a solid object, it can also detect liquids (used in the Cheers group).
There are four pins on the HC-SR04 Ultrasonic distance sensor:
- Vcc: power.
- GND: ground.