Echolocation / Sonar Navigation

This demo is designed to introduce an example of selecting a a sensor, identifying its properties, finding sample code, implementing code and testing, modifying code, and actuating lights and sounds as an output. Let’s get started.

Process:

  1. Obtain a sensor, for example the HY-SRF04 or 05 ultrasonic rangefinder ($6).  Other great sources are Adafruit.com, Sparkfun.com.
  2. Search for information on using it. Adafruit is best for teaching and providing tutorials and code.  Since the rangefinder is from Amazon, we need to Google it.
  3. Find a datasheet and sample code.  Copy and paste code to a new Codebender script.  The code describes the pin connections, here it needs (1) +5V power, (2) ground, (3) “trigger” digital input, and (4) “echo” digital output.
  4. Wire up the circuit.
  5. Verify the code and install it on your Arduino.  The code triggers the ultrasonic sensor to emit 8 pulses, receive an echo, and output a pulse to the echo pin with a duration equal to the echo delay.  A variable reads this time delay in microseconds.  Using the speed of sound in air (343.2 m/s at 20C) and echo appearing at twice the distance (there and back), the distance in cm is given by L(cm) = t(us) * 0.03432 cm/us / 2.  The distance is written out to the serial port.
  6. Select Serial Monitor on Codebender and Start at the bottom. Ultrasonic range distance data should appear about once per second.

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