PJ034: Ultrasonic Proximity Detection with HC-SR04

❓Explore by yourself:

• What is HC-SR04? Why does it have 2 "heads"? Which is Transmitter and Receiver?

• How does it work theoretically with ultrasonic wave?

• How to wire it with microcontrollers?

• What can we use ultrasonic sensors for?

• What is a Library in program? What lib available for HC-SR04?

References:

KB016: Ultrasonic Sensor 

TM019: Ultrasonic Sensor HC-SR04 

... and lots of information from internet and AI

Challenge:

If the time cost for go-back is 500 µs, then how long distance is it away?

Since the measurement sometimes jumps, if use it for decision, it could be tricky and risky, what can we do in program to redue this noise?

Here is an example snippet, can you integrate into your code and test? Share with the class about what you find.

float getAverageDistance(int samples) {

  float sum = 0;

  for (int i = 0; i < samples; i++) {

    float d = hcsr04.measureDistanceCm();

    if (d > 0) sum += d;

    delay(20);

  }

  return sum / samples;

}