Sound Library

The mikroC PRO for 8051 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).

External dependencies of Sound Library

The following variables must be defined in all projects using Sound Library:	Description:	Example :
`extern sfr sbit bdata Sound_Play_Pin;`	Sound output pin.	`sbit Sound_Play_Pin at P0_3_bit;`

Sound_Init

Prototype	void Sound_Init();
Returns	Nothing.
Description	Configures the appropriate MCU pin for sound generation.
Requires	`Sound_Play_Pin` variable must be defined before using this function.
Example	// Initialize the pin P0.3 for playing sound sbit Sound_Play_Pin at P0_3_bit; ... Sound_Init();

Sound_Play

Prototype	void Sound_Play(unsigned freq_in_hz, unsigned duration_ms);
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/(803)`. Minimum frequency is `Freq_min = Fosc/(80255)`. 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 1 kHz 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.

// Sound connections
sbit Sound_Play_Pin at P0_3_bit;
// End Sound connections


void Tone1() {
  Sound_Play(659, 250);   // Frequency = 659Hz, duration = 250ms
}

void Tone2() {
  Sound_Play(698, 250);   // Frequency = 698Hz, duration = 250ms
}

void Tone3() {
  Sound_Play(784, 250);   // Frequency = 784Hz, duration = 250ms
}

void Melody() {           // Plays the melody "Yellow house"
  Tone1(); Tone2(); Tone3(); Tone3();
  Tone1(); Tone2(); Tone3(); Tone3();
  Tone1(); Tone2(); Tone3();
  Tone1(); Tone2(); Tone3(); Tone3();
  Tone1(); Tone2(); Tone3();
  Tone3(); Tone3(); Tone2(); Tone2(); Tone1();
}

void ToneA() {
  Sound_Play( 880, 50);
}
void ToneC() {
  Sound_Play(1046, 50);
}
void ToneE() {
  Sound_Play(1318, 50);
}

void Melody2() {
  unsigned short i;
  for (i = 9; i > 0; i--) {
    ToneA(); ToneC(); ToneE();
  }
}

void main() {
  P1 = 255;                     // Configure PORT1 as input
  Sound_Init();                 // Initialize sound pin
  
  Sound_Play(2000, 1000);       // Play starting sound, 2 kHz, 1 second

  while (1) {                   // endless loop
  
    if (!(P1_7_bit))            // If P1.7 is pressed play Tone1
      Tone1();                  // 
    while (!(P1_7_bit)) ;       // Wait for button to be released

    if (!(P1_6_bit))            // If P1.6 is pressed play Tone2
      Tone2();                  //
    while (!(P1_6_bit)) ;       // Wait for button to be released

    if (!(P1_5_bit))            // If P1.5 is pressed play Tone3
      Tone3();                  //
    while (!(P1_5_bit)) ;       // Wait for button to be released

    if (!(P1_4_bit))            // If P1.4 is pressed play Melody2
      Melody2();                //
    while (!(P1_4_bit)) ;       // Wait for button to be released

    if (!(P1_3_bit))            // If P1.3 is pressed play Melody
      Melody();                 //
    while (!(P1_3_bit)) ;       // Wait for button to be released
  }
}

HW Connection

Example of Sound Library connection

Want more examples and libraries?
Find them on