Materials for this activity:
Items for Part 1
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Ultrasound Sensor
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Jumper Wires
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Arduino and USB Connector
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These are for part 2
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LEDs
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Buzzer
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Breadboard
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What is Ultrasound?
Several animals send out high frequency sound that reflects off of other objects. They then sense their own reflected sound when it comes back. The loudness and time it takes to come back depends on the distance to the object.
Watch RCC's Mrs. Miller Introduce Ultrasound
Ultrasound sensor wiring and coding basics
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Wire up your ultrasonic sensor like this picture.
VCC is connected to the 5V Arduino pin Trig is connected to Arduino pin 3 Echo is connected to Arduino pin 2 Gnd is connected to an Arduino GND pin |
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Now that you have it wired, you are ready to type in the example code.
Here is the code with descriptions of what each line does.
Verify and upload the code to the board
Making the Arduino Light Up if you get to close
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We will now add a little bit to our code so that when you get closer than three feet to something, a light will turn on. Three feet is 91 centimeters, we will need to know that number later. You can pick a different difference away. Every foot is about 30 cm.
To do this, we have to add what is called a condition. This can be done with an "if/else" statement. |
Here is an example of an if/else we can add before the end of our code to do this.
Put this right after the last code's Serial Prints and the delay. What this does is if the distance is between 0 and 91 cm, then the light is on, otherwise the light is off.
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We also need to define the LED's location and that it's pin would be an output. Let's add to the ultrasound code to do that similar to the example below.
Example Wiring |
Example Code |
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The only thing we are adding is the LED to GND and pin 13. Remember to use a blue or white light if you do not want to use a resistor. If you want to use a different color light, you will need to add a 220 or 330 Ohm resistor to the light. Ask your teacher about how to do this before doing it though.
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Verify and Upload Code to the Board, Does it Work?
Is the code working, what is happening? Ask your teacher for help if you need it.
Trying the Buzzer
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If you got your light to shine when you got too close to the sensor, then you can do the same thing but with the buzzer instead.
Replace the light with a buzzer and see if it now buzzes when you get too close! After that works, use your breadboard by connecting a wire to GND to - and pin 13 to the + rail. Then you can plug as many lights and buzzers in parallel to the breadboard rail. See if you can control multiple things at once with the ultrasound sensor. |
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This lesson was inspired by a Dr.Duino lesson: www.drduino.com
hackaday.com/2020/04/09/ultrasonic-sensor-helps-you-enforce-social-distancing/ |
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