PaperS3 buzzer related APIs and example programs.
#include <M5Unified.h>
#include <M5GFX.h>
void setup() {
  M5.begin();
  M5.Display.setRotation(0);
  M5.Display.setFont(&fonts::DejaVu40);
  M5.Display.print("\nStart playing\nmusical scale");
  M5.Speaker.setVolume(200);  // 0~255, bigger is louder
}
void loop() {
  M5.update();
  M5.Speaker.tone(880, 500);  // frequency (Hz), duration (ms)
  delay(500);
  M5.Speaker.tone(990, 500);
  delay(500);
  M5.Speaker.tone(1120, 500);
  delay(500);
  M5.Speaker.tone(1180, 500);
  delay(500);
  M5.Speaker.tone(1320, 500);
  delay(500);
  M5.Speaker.tone(1480, 500);
  delay(500);
  M5.Speaker.tone(1650, 500);
  delay(500);
  M5.Speaker.tone(1760, 500);
  delay(1000);
  M5.Speaker.tone(1760, 500);
  delay(500);
  M5.Speaker.tone(1650, 500);
  delay(500);
  M5.Speaker.tone(1480, 500);
  delay(500);
  M5.Speaker.tone(1320, 500);
  delay(500);
  M5.Speaker.tone(1180, 500);
  delay(500);
  M5.Speaker.tone(1120, 500);
  delay(500);
  M5.Speaker.tone(990, 500);
  delay(500);
  M5.Speaker.tone(880, 500);
  delay(1000);
}This program will play the scales 12345671 and 17654321.
// Happy birthday song
#include <M5Unified.h>
#include <M5GFX.h>
void setup() {
  M5.begin();
  M5.Display.setRotation(0);
  M5.Display.setFont(&fonts::FreeMonoBold24pt7b);
  M5.Display.print("\n\n   Happy birthday\n   to\n   you\n\n\n");
  M5.Display.print("      i  i  i\n     |:|:|:|:|\n    |||||||||||\n   {~~~~~~~~~~~}\n  [#############]\n  |#############|\n  |#############|\n  \\_____________/\n");
  M5.Speaker.setVolume(200);  // 0~255, bigger is louder
}
void loop() {
  M5.update();
  playHappyBirthday();
}
void playHappyBirthday() {
  int notes[] = {
    1320, 1320, 1480, 1320, 0, 1760, 1650, 0,
    1320, 1320, 1480, 1320, 0, 1980, 1760, 0,
    1320, 1320, 2600, 2200, 0, 1760, 1650, 1480, 0,
    2350, 2350, 2200, 1760, 0, 1980, 1760, 0
  };
  int durations[] = {
    300, 300, 600, 400, 200, 600, 600, 300,
    300, 300, 600, 400, 200, 600, 600, 300,
    300, 300, 600, 400, 200, 600, 600, 600, 300,
    300, 300, 600, 400, 200, 600, 600, 300
  };
  int count = sizeof(notes) / sizeof(int);
  for (int i = 0; i < count; i++) {
    if (notes[i] == 0) {
      delay(durations[i]);
    } else {
      M5.Speaker.tone(notes[i], durations[i]);
      delay(durations[i] + 30);
    }
  }
}This program will play the Happy Birthday song and display a cake on the screen.
The buzzer part of PaperS3 uses the Speaker_Class from the M5Unified library. For more related APIs, please refer to the documentation below: