Week 10 — Assignment

Concept

Our musical instrument is based off a combination of a both a mechanical and digital noise machine–controlled with a surprisingly satisfying potentiometer that allows us to modify the beats per minute (BPM), and a button that changes the octave of our instrument. We had fun with the relationship between the buzzer and our mechanical servo which produces the other noise, where the two are inversely proportional! In other words,  as the BPM of the buzzer increases, the servo slows down! And vice versa.

Figuring out the right code combination was a bit tricky at first, as we first made the mistake of nesting both the servo trigger and the buzzer tone in the same beat conditional. This meant that we fundamentally could not separate the motor from the buzzer tones. To resolve this, we ended up using two triggers–a buzzer and a motor trigger–which both run independently.

The code below shows how we ended up resolving this problem. Once we implemented this fix, we were able to celebrate with our somewhat perplexing instrument, that requires the user to complement the buzzers various beeping with the servos mechanical changes.

// --- 3. Perform Actions based on Timers ---

// --- Action Group 1: Metronome Click (Buzzer) ---
if (currentMillis - previousBeatMillis >= beatInterval) {
  previousBeatMillis = currentMillis; // Store the time of this beat

  // Play the click sound
  tone(BUZZER_PIN, currentFreq, CLICK_DUR);

  // Print beat info
  Serial.print("Beat! BPM: ");
  Serial.print(currentBPM);
  Serial.print(" | Freq: ");
  Serial.print(currentFreq);
  Serial.print(" | Beat Interval: ");
  Serial.print(beatInterval);
  Serial.println("ms");
}

// --- Action Group 2: Servo Movement Trigger ---
if (currentMillis - previousServoMillis >= servoInterval) {
  previousServoMillis = currentMillis; // Store the time of this servo trigger

  // Determine Target Angle
  int targetAngle;
  if (servoMovingToEnd) {
    targetAngle = SERVO_POS_END;
  } else {
    targetAngle = SERVO_POS_START;
  }

  // Tell the servo to move (NON-BLOCKING)
  myServo.write(targetAngle);

  // Print servo info
  Serial.print("Servo Trigger! Target: ");
  Serial.print(targetAngle);
  Serial.print("deg | Servo Interval: ");
  Serial.print(servoInterval);
  Serial.println("ms");

  // Update state for the next servo trigger
  servoMovingToEnd = !servoMovingToEnd; // Flip the direction for next time
}