The mikroPascal PRO for AVR provides a Sound Library to supply users with routines necessary for sound signalization in their applications. Sound generation needs additional hardware, such as piezo-speaker (example of piezo-speaker interface is given on the schematic at the bottom of this page).

Library Routines

• Sound_Init
• Sound_Play

Sound_Init

// Initialize the pin RC3 for playing sound
Sound_Init(PORTC, 3);

Sound_Play

Prototype	procedure Sound_Play(freq_in_hz, duration_ms : word);
Returns	Nothing.
Description	Generates the square wave signal on the appropriate pin. Parameters : freq_in_hz: signal frequency in Hertz (Hz) duration_ms: signal duration in miliseconds (ms)   Note : Frequency range is limited by Delay_Cyc parameter. Maximum frequency that can be produced by this function is Freq_max = Fosc/(80*3). Minimum frequency is Freq_min = Fosc/(80*255). Generated frequency may differ from the freq_in_hz parameter due to integer arithmetics.
Requires	In order to hear the sound, you need a piezo speaker (or other hardware) on designated port. Also, you must call Sound_Init to prepare hardware for output before using this function.
Example	// Play sound of 1KHz in duration of 100ms Sound_Play(1000, 100);

Library Example

The example is a simple demonstration of how to use the Sound Library for playing tones on a piezo speaker.

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program Sound;

procedure Tone1();
  begin
    Sound_Play(659, 250);            // Frequency = 500Hz, Duration = 200ms
  end;

procedure Tone2();
  begin
    Sound_Play(698, 250);            // Frequency = 555Hz, Duration = 200ms
  end;

procedure Tone3();
  begin
    Sound_Play(784, 250);            // Frequency = 625Hz, Duration = 200ms
  end;

procedure Melody();                  // Plays the melody "Yellow house"
  begin
    Tone1(); Tone2(); Tone3(); Tone3();
    Tone1(); Tone2(); Tone3(); Tone3();
    Tone1(); Tone2(); Tone3();
    Tone1(); Tone2(); Tone3(); Tone3();
    Tone1(); Tone2(); Tone3();
    Tone3(); Tone3(); Tone2(); Tone2(); Tone1();
  end;

procedure ToneA();                   // Tones used in Melody2 function
  begin
    Sound_Play(880, 50);
  end;
  
procedure ToneC();
  begin
    Sound_Play(1046, 50);
  end;
  
procedure ToneE();
  begin
    Sound_Play(1318, 50);
  end;

procedure Melody2();                 // Plays Melody2
var counter : byte;
  begin
    for counter := 9 downto 1 do
      begin
        ToneA();
        ToneC();
        ToneE();
      end;
  end;

begin

  DDRB := 0x00;                      // Configure PORTB as input
  Delay_ms(2000);
  Sound_Init(PORTC,3);               // Initialize sound pin
  
  Sound_Play(2000, 1000);            // Play starting sound, 2kHz, 1 second

  while TRUE do                      // endless loop
    begin
      if (PINB7_bit <> 0) then          // If PORTB.7 is pressed play Tone1
      begin
        Tone1();
        while (PINB7_bit <> 0) do nop;  // Wait for button to be released
      end;

      if (PINB6_bit <> 0) then          // If PORTB.6 is pressed play Tone2
      begin
        Tone2();
        while (PINB6_bit <> 0) do nop;  // Wait for button to be released
      end;
      
      if (PINB5_bit <> 0) then          // If PORTB.5 is pressed play Tone3
      begin
        Tone3();
        while (PINB5_bit <> 0) do nop;  // Wait for button to be released
      end;
      
      if (PINB4_bit <> 0) then          // If PORTB.4 is pressed play Melody2
       begin
        Melody2();
        while (PINB4_bit <> 0) do nop;  // Wait for button to be released
      end;
      
      if (PINB3_bit <> 0) then          // If PORTB.3 is pressed play Melody
      begin
        Melody();
        while (PINB3_bit) do nop ;      // Wait for button to be released
      end;
    end;
end.

HW Connection

Example of Sound Library connection

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