Welcome to the Ada for micro:bit series where we look at simple examples to learn how to program the BBC micro:bit with Ada.
If you haven't already, please follow the instructions in Part 1 to setup your development environment.
In this eighth part we will see how to play some simple music with the micro:bit and a piezo buzzer.
In the analog output example we said that the analog output was actually a Pulse Width Modulation (PWM) signal. When a piezo buzzer is connected to a PWM a note is produced, changing the frequency of the PWM signal means changing the note that the buzzer will play.
For this example we will need a couple of extra parts:
- A breadboard
- A piezo buzzer
- A couple of wires to connect them
MicroBit.Music provides different ways to play music. We are going
to use the procedure that plays a melody. A
Melody is an array of
Note is made of a pitch and a duration in milliseconds. This package
also provides declaration of pitches for the chromatic scale (e.g
So we declare our little melody like so:
My_Little_Melody : constant MicroBit.Music.Melody := ((C4, 400), (G3, 800), (B3, 400), (Rest, 400), (A3, 400), (G3, 400));
Then we simply have to call the procedure
Play of the package
procedure Play (Pin : Pin_Id; M : Melody) with Pre => Supports (Pin, Analog);
- Pin : The id of the pin that the melody will play on
- M : The melody that we want to play
- The procedure
Playhas a precondition that the pin must support analog IO.
Here is the full code of the example:
with MicroBit.Music; use MicroBit.Music; procedure Main is My_Little_Melody : constant MicroBit.Music.Melody := ((C4, 400), (G3, 800), (B3, 400), (Rest, 400), (A3, 400), (G3, 400)); begin -- Loop forever loop -- Play the little melody on pin 0 MicroBit.Music.Play (0, My_Little_Melody); end loop; end Main;
Following the instructions of Part 1 you can open this example (Ada_Drivers_Library-master\examples\MicroBit\music\music.gpr), compile and program it on your micro:bit.
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