Passive Buzzer

# Passive Buzzer A passive buzzer requires an external signal to create sound. It does not have a built-in oscillator, so it relies on a square wave signal or frequency input from the microcontroller to produce sound. To produce different tones with a **passive buzzer** using the arduino, you can generate varying frequencies using the tone() function, which takes the frequency as a parameter. Different frequencies correspond to different musical notes or pitches. By altering the frequency, you can control the pitch of the sound produced by the buzzer. ```cpp #define BUZZER_PIN 3 // Pin for passive buzzer // Define some musical notes' frequencies (in Hz) #define NOTEC4 261 // C4 (Middle C) #define NOTED4 294 // D4 #define NOTEE4 329 // E4 #define NOTEF4 349 // F4 #define NOTEG4 392 // G4 #define NOTEA4 440 // A4 #define NOTEB4 466 // B4 void setup() { pinMode(BUZZER_PIN, OUTPUT); // Set the buzzer pin as output } void loop() { // Play some musical notes with delays tone(BUZZER_PIN, NOTEC4); // Play C4 delay(500); tone(BUZZER_PIN, NOTED4); // Play D4 delay(500); tone(BUZZER_PIN, NOTEE4); // Play E4 delay(500); tone(BUZZER_PIN, NOTEF4); // Play F4 delay(500); tone(BUZZER_PIN, NOTEG4); // Play G4 delay(500); tone(BUZZER_PIN, NOTEA4); // Play A4 delay(500); tone(BUZZER_PIN, NOTEB4); // Play B4 delay(500); // Stop the tone for a moment before repeating noTone(BUZZER_PIN); delay(1000); } ``` ```cpp #define NOTEA4 440 ``` This defines a **preprocessor macro** named NOTEA4 and assigns it the value 440. It represents the frequency (in Hertz) of the musical note A4, which is 440 Hz. By using a macro like NOTEA4, the code becomes more readable and self-explanatory. Instead of writing 440, you can use the musical note name directly in your code. ```cpp tone(BUZZER_PIN, NOTEA4); ``` This generates a square wave at the frequency specified by NOTEA4 (440 Hz in this case) on the pin defined by BUZZER_PIN (e.g., pin 23). The tone() function works by setting up a timer to toggle the pin between HIGH and LOW states at the frequency you provide (in this case, 440 Hz). This toggling creates a square wave that drives the passive buzzer. ```cpp noTone(BUZZER_PIN); ``` Stops the tone generation on the specified pin (BUZZER_PIN). This effectively silences the passive buzzer. The noTone() function disables the timer and stops toggling the pin, leaving the pin in a LOW state.