The HC-SR04 module measures distance to objects by means of ultrasonic reflection. This is done by firing pulses of 40 kHz to the environment, after which the time required to receive the reflected signals is measured. By dividing this time by a constant, the distance can be determined fairly precisely (up to 0.3 cm precision!). Works with all hard surfaces (the sound must be able to be reflected).Properties:
- Voltage: 5V
- Current: <2 mA.
- Output: Digital, high 5V, low 0V.
- Sensor angle: around 15 degrees.
- Detection distance: 2 cm - 450 cm (measurable with; pulse width (uS) / 58 = distance (cm).
- Precision: up to 0.3 cm
- Input trigger signal: 10us high
- Echo signal: High for x uS