Ultrasonic sensor HC-SR04

HC-SR04 is a commonly used ultrasonic sensor, compatible with all micro-control boards (eg Arduino), it can detect whether there is an obstacle in front, and the distance between the sensor and the obstacle. The principle is the same as that of detecting the surrounding environment when a bat is flying. It emits a high-frequency ultrasonic signal that cannot be heard by humans. When this signal hits an obstacle, it will be reflected back. The time difference during this period will be used to calculate the distance between the sensor and the obstacle.

Spec:
Wire length: 200mm
Detection distance: 2cm (minimum), 3-4m (maximum)
Working voltage: 5V
Working current: 15mA
Working frequency: 40khz