Build Instructions

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• 1

  Construction- Wiring

  • We began the wiring of this project by first joining the GND terminals of every button, which will be connected to the expansion board's GND.
  • We next connected each switch's I/O pin by following the wiring diagram. We use 8 GPIO as we are using 8 switches.
  • The expansion board's battery connector was soldered with battery terminals.
• 2

  CODE

  After finalizing the wiring connection process, we uploaded the below code into the XIAO EXP32 S3 board.

  #include <Wire.h>
  #include <Adafruit_GFX.h>
  #include <Adafruit_SSD1306.h>
  #define SCREEN_WIDTH 128
  #define SCREEN_HEIGHT 64
  #define SSD1306_I2C_ADDRESS 0x3C
  // Declaration for SSD1306 display connected using I2C (default address 0x3C)
  Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT);
  const int buttonPins[] = {0, 1, 2, 6, 7, 8, 9, 10}; // Button pins
  const int buttonCount = 8;
  const int speakerPin = D3; // Speaker pin
  // Define frequencies for each button
  const int frequencies[8] = {523, 587, 659, 698, 784, 880, 988, 1047}; // C5 to C6
  void setup() {
  // Initialize the display
  if (!display.begin(SSD1306_I2C_ADDRESS, 0x3C)) {
  for (;;);
  }
  display.display();
  delay(2000); // Pause for 2 seconds
  display.clearDisplay();
  display.setTextSize(4);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(5, 20);
  display.println(F("SYNTH"));
  display.display();
  // Initialize button pins as input with pull-up resistors
  for (int i = 0; i < buttonCount; i++) {
  pinMode(buttonPins[i], INPUT_PULLUP);
  }
  pinMode(speakerPin, OUTPUT);
  noTone(speakerPin); // Ensure the speaker is off initially
  }
  void loop() {
  bool buttonPressed = false;
  for (int i = 0; i < buttonCount; i++) {
  int buttonState = digitalRead(buttonPins[i]);
  if (buttonState == LOW) { // Button pressed
  tone(speakerPin, frequencies[i]); // Play tone
  // Flash the display with button press info
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.print("Button ");
  display.print(i + 1); // Display button index (1-based)
  display.println(" pressed");
  display.display();
  buttonPressed = true;
  }
  }
  // Turn off the speaker if no button is pressed
  if (!buttonPressed) {
  noTone(speakerPin);
  } else {
  delay(100); // Hold the display for a short period
  display.clearDisplay();
  display.display(); // Clear the display after a button press
  }
  delay(100); // Debounce delay
  }

  Here's a short breakdown for the code.

  #include <Wire.h>#include <Adafruit_GFX.h>#include <Adafruit_SSD1306.h>

  These libraries are included to control the I2C communication (Wire.h) and to interface with the SSD1306 OLED display (Adafruit_GFX.h and Adafruit_SSD1306.h).

  const int buttonPins[] = {0, 1, 2, 6, 7, 8, 9, 10}; // Button pinsconst int buttonCount = 8;const int speakerPin = D3; // Speaker pinconst int frequencies[8] = {523, 587, 659, 698, 784, 880, 988, 1047}; // C5 to C6

  This specifies the GPIO pins used for buttons and the speaker. Also defines the frequencies corresponding to each button, representing musical notes from C5 to C6.

• 3

  Final Assembly

  • Following the completion of the electronics and coding, we began the main assembly procedure, which begins with the battery positioned between the two frames. The Xiao expansion board is then installed in its location, and it is fastened in place with M2 screws.
  • The button board is then positioned and fastened in place with M2 screws.

  The assembly process is now complete.

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