Getting Started with MicroPython and the SparkFun Inventor's Kit for micro:bit

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Contributors: LightningHawk
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Experiment 9: Using a Buzzer

Introduction

In this experiment, we will again bridge the gap between the digital world and the analog world. We’ll be using a piezo buzzer that makes a small “click” when you apply voltage to it (try it!). By itself that isn’t terribly exciting, but if you turn the voltage on and off hundreds of times a second, the piezo buzzer will produce a tone. And if you string a bunch of tones together, you’ve got music! This circuit and set of code blocks will create a simple sound machine.

Parts Needed

You will need the following parts:

  • 1x Breadboard
  • 1x micro:bit
  • 1x micro:bit Breakout with Headers
  • 1x Piezo Buzzer
  • 2x Momentary Push Buttons
  • 7x Jumper Wires

Didn’t Get the SIK for micro:bit?

If you are conducting this experiment and didn’t get the Inventor’s Kit, we suggest using these parts:

Breadboard - Self-Adhesive (White)

PRT-12002
$4.95
35
micro:bit Board

DEV-14208
$14.95
3
SparkFun micro:bit Breakout (with Headers)

BOB-13989
$5.49
Jumper Wires - Connected 6" (M/M, 20 pack)

PRT-12795
$1.95
2
Momentary Pushbutton Switch - 12mm Square

COM-09190
$0.50
4
Mini Speaker - PC Mount 12mm 2.048kHz

COM-07950
$1.95
5

Introducing the Piezo Buzzer

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The buzzer is a small component with a piece of metal in it that moves when you apply a voltage across it. This motion causes a small sound, or “click.” If you turn the voltage on and off fast enough, you get different beeps, squeals, chirps and buzzes. You will use PWM to control the speed of turning the piezo on and off — and, in turn, the audio frequency coming out of the buzzer. Adjusting the PWM enables you to get legitimate notes out of the buzzer.

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If you flip the buzzer over and look at the bottom, you will see that one pin has a (+) next to it. That pin gets connected to a signal from the P0 pin. The other pin should be connected to ground.

Hardware Hookup

Ready to start hooking everything up? Check out the wiring diagram below to see how everything is connected.

Pay special attention to the component’s markings indicating how to place it on the breadboard. Polarized components can only be connected to a circuit in one direction.

Wiring Diagram for the Experiment

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Having a hard time seeing the circuit? Click on the wiring diagram for a closer look.

Note: The full-sized breadboard power rails have a break down the middle. If you end up using the lower half of the power rail, you will need to jump between the upper end and lower end.

Run Your Script

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Code to Note

music

MicroPython has an awesome music and sound module. We spent hours generating tones and writing songs in the REPL. As you learn to compose your own music on the micro:bit we highly recommend using the REPL to become familiar with all the sounds — plus the help() feature is nice when you want to see (hear) what you can do.

The music module has 21 melodies built in. To see a list, begin typing music.play(_... in the Mu editor, and the list should pop up.

To get an in-depth tutorial on the music module, click here.

music.play()

To play a tune you need to specify a note (A, C#, F), an octave (0–8) and a duration (how long the note will be played). For example, if the button on pin 15 is pressed, the note C in octave 4 will play for a duration of 8.

What You Should See

What you should see — well, nothing! What you should hear — each button has its own tune. Enjoy your sound machine and feel free to swap out the song and tunes of your choice. Add more buttons and play statements to make your custom piano!

Try it again but with a real speaker. At the press of a button you could play the funeral march, Happy Birthday or the Nyan Cat theme with much better audio!

Troubleshooting

No Sound

Given the size and shape of the piezo buzzer, it is easy to miss the right holes on the breadboard. Try double checking its placement.

Also, double check to make sure the push button is wired correctly. If you miswired it, then the circuit will never be completed, whether you press the button or not.