Metronome

Step 1: Make it

What is it?

Code your own electronic metronome that makes regular beats which you can slow down and speed up as you practice music.

What you'll learn

• How to adjust the tempo of musical notes played by the micro:bit
• How to use input buttons and audio outputs to make a useful electronic device

How it works

• At the start of the program, it sets the tempo to 100 bpm - beats per minute. This is a standard way of measuring the tempo, or speed, of music.
• A forever loop keeps the micro:bit playing a short note and then resting for one beat.
• You can hear the sound by attaching headphones to pin 0 and GND or on the built-in speaker of the new micro:bit.
• Press button A to slow down the tempo by 5 bpm.
• Press button B to speed it up by 5 bpm.
• Pressing button A and B together shows the current tempo on the LED display output.

What you need

• A micro:bit
• MakeCode or Python editor
• battery pack (optional)

Step 2: Code it

1from microbit import *
2import music
3tempo = 100
4
5while True:
6    music.set_tempo(bpm=tempo)
7    music.play(['C4:1', 'r:3']) # play C for 1 tick, rest for 3 ticks
8    if button_a.was_pressed():
9        tempo -= 5
10    if button_b.was_pressed():
11        tempo += 5  
12    

Step 3: Improve it

• You may notice that it plays its rhythm slightly slower than an electronic instrument with the same BPM setting - this is because each loop takes one and one sixteenth of a beat, instead of just one beat.
• You could try and make it more accurate by adding up fractions of a beat to make one whole beat: 1/2 + 1/4 + 1/8 + 1/16 makes 15/16 to add on the 1/16th of a beat that you’re playing the tone for.
• 'Forever' blocks also add a bit of a delay, so using a ‘while true’ loop inside it will speed up your code and make it more accurate.
• The code video at the top of this page shows you how to do this.