Week 10 – Musical Instrument

by Ajla and Hana


This week’s assignment was to create a simple musical instrument using the Arduino. Hana and Ajla decided to create a simplified piano and drum. In order to do so, we utilized switches and a servo motor. We controlled the speed of the servo motor using a potentiometer. The notes are played by pressing the buttons. The buttons stop producing noise when released.

Servo circuit



To implement our musical instrument, we used a potentiometer, switches, a piezoelectric buzzer, resistors, wires and an Arduino. By connecting the switches in parallel we were able to preserve voltage across all components. Even though it was possible to connect everything on one breadboard, we decided to separate it in order to make the instrument user friendly. Furthermore, since many digital inputs were used, the separation ensured that there would not be any overcrowding while presenting the final product.The sketches below show both the two Arduino setup we used and one Arduino setup.

The code was written for both Arduino. Hana wrote the code for the switches and Ajla wrote the code for the drum. The drum was made using a metal screw, silk ribbon and tape which was attached to the servo hand. By pressing the four switches, notes, stored in an array, were played. The drum hit a piece of cardboard in order to produce noise.

Two Arduino
One Arduino

Here is the code for playing the notes:

// if button1 is pressed, plays first note
  if(button1State==1) {
    tone(9, notes[0]);

// if button2 is pressed, plays second note

  if(button2State==1) {
    tone(9, notes[1]);

// if button3 is pressed, plays third note

  if(button3State==1) {
    tone(9, notes[2]);

// if button4 is pressed, plays fourth note

  if(button4State==1) {
    tone(9, notes[3]);

// if buttons are release, no note is played

  if(button1State==0 && button2State==0  && button3State==0 && button4State==0) {
  delay(1);  // delay in between reads for stability

Here is the code that ran the servo in a 90 degree range:

void loop() {
  int p_value  = analogRead(p_meter);

  int value = map(p_value, 0, 1024, 10, 20);
  for (int i=45; i<90; i += value) {
    pos1 = 0 + (i*2);          // servo1 from 0 to 90 degrees
    myservo1.write(pos1);      // move the servo
  for (int i=45; i<90; i += value) {
    pos1 = 90 - i*2;           // servo1 from 90 to 0 degrees
    myservo1.write(pos1);      // move the servo


The assignment came with a few challenges. Firstly, since the piezoelectric buzzer cannot take multiple inputs at once, it was important to play each note once, without pressing others since that would destroy the quality of the sound. Secondly, the notes play continuously if the button is pressed, even once. That is why we added the last if statement that checks whether all buttons are not pressed, in which case it plays no sound. Thirdly, the servo is quite tricky to use at high speeds. It gets more imprecise as the speed goes up. So, controlling it with the potentiometer was quite hard to do precisely. Lastly, since the angle of motion changes as the speed increases, it was hard to mount the servo on anything as it would immediately fall down once the speed was changed. This became quite frustrating that we decided to just hold the servo in the end to showcase the tempo of the “drum”. All in all, this assignment came with quite a few challenges. Some of them we tried to attempt and won, such as the notes, but some of them remain to be defeated due to the lack of time and materials we had at the time of making this project.


Our team went back and forth on ideas on what to do as an instrument because neither of us are musically inclined. However, we landed on this idea after a few iterations. We struggled quite a bit to get everything right, as was mentioned in the challenges above, but we overcame them with solutions such as only playing one note at a time, and having to hold the servo since it would not stay mounted. Overall, it was a great learning experience, but I realized that for the final project I will most probably not delve into anything sound or music related since my creativity is a lot more limited.

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