Ultrasonic Sonic Sensor

How it Works

The Ultrasonic Sensor is an electronic device that converts the ultrasonic sound wave into an electric signal. The HC SR04 sensor module consists of an ultrasonic transmitter, a receiver, and a control circuit. When it is triggered by a HIGH-LOW pulse at the ‘Trig’ pin, the transmitter emits a sonic burst of 8 pulses( 40 kHz ultrasonic frequency). These pulses when hit by an object, get reflected and received by the sensor(receiver). The control system process these pulses and sends them to the ‘Echo’ pin. Which further can be read by a microcontroller.

Specifications

Steps for an Operation

Set the trigger pulse to HIGH for 10 Microseconds and then set it LOW (Negative Trigger).
The Module gets triggered and emits 8 continuous pulses at 40 kHz frequency.
After triggering is done, start the timer on the microcontroller.
The Module waits for the echo signal (Measurement cycle should be over 60 milliseconds to prevent Trigger signal to the echo signal).
When the receiver detects the echo pulse, it sends these pulses to the echo pin of the module.
When the microcontroller detects the high pulse at the echo pin, stop the timer.
The time measured by the microcontroller is two times the time when pulses hit the object. So, the actual time is calculated by the measured time divided by two.