Playing Tones using Piezoelectric Buzzer and PIC PWM

Hello! Everyone, in my last post i showed you guys to use Microchip PIC's Capture and Compare Module to generate PWM signal. If you haven't read that post then please click on the link below, to read it, as this project uses the last project libraries.
Generating PWM Signal Using PIC Micro-controller.
So in this post i will take the above project code as base code and start modifying it to generate tones of different frequency, and we will generate the tone SA, RE, GA, MA, PAA, DHI, NII, SAA using the PIC Micro-controller and piezoelectric buzzer.
The simulation diagram for this project is as follow:

Simulation Diagram

I am going to use 50% duty cycle in all cases, and will only adjust the frequency as per the note which i am want to play.
The following components are present in this simulation diagram:

• PIC18F45K50 micro-controller, this is used for generating PWM, you can use any PIC16F or PIC18F, the same code can be used with little or no changes.
• 16X2 Lcd, is used to display the note which is playing, the LCD is working in 4-bit mode and that too using busy flag check, click here to read all the post related to lcd.
• 2 Push Buttons are also present and they are used to start and stop tone generation.

So when you press the Start Button, it will start the tone sequence and you will hear the SA, RE, GA, MA, PA, DHA, NII, SAA tone from your buzzer. And when you press the stop button, the tone generation stops.

This project can be modified to generate lots of other tones, provided that you know the frequency of the note you want to play, and then you can use the PWM functions to generate that frequency signal.

The main program for this project is as follows:

/*

 * File:   main.c

 * Author: Embedded Laboratory

 *

 * Created on June 4, 2017, 10:24 PM

 */

#include "config.h"

#include "lcd_16x2.h"

#include "keypad.h"

#include "pwm.h"

/* Project */

Task_s lcdTask        = { TRUE,   1000u,   0u };

Task_s keyTask        = { TRUE,   30u,     0u };

/* Global Variables for this file*/

static char lcd_msg[LCD_BUFFER_LEN] = { 0 };

static u8_t keyPress = 0;

#define SAREGAMAPA_SIZE     7u

u16_t saregamapa[SAREGAMAPA_SIZE] = \

                          {2441u, 2741u, 3048u, 3255u, 4058u, 4562u, 4882u};

char tone_display[][SAREGAMAPA_SIZE] =

{

  "SA",

  "RE",

  "GA",

  "MA",

  "PAA",

  "DHA",

  "NII",

  "SAA"

};

/* Function Prototypes*/

void Initialize_IO( void );

/* Main Program*/

void main()

{

  u8_t duty_cycle = 50u;

  static u8_t index = 0u;

  boolean start = FALSE;

  Initialize_IO ();

 

  LCD_Print_Line (0, (char*)"Embedded");

  LCD_Print_Line (1, (char*)"      Laboratory");

  LCD_Update ();

 

  while(1)

  {

    // Get Key Task

    // if( millis() - keyTask.timestamp > keyTask.period )

    {

      keyPress = getKey ();

      if (keyPress!=NO_KEY && keyPress < MAX_KEY_SIZE )

      {

        keyPress = KeyMap[keyPress-1];

      }

    }

   

    // LCD Update Task

    if( (millis() - lcdTask.timestamp > lcdTask.period)

         || (keyPress == START_KEY || keyPress == STOP_KEY) )

    {

      lcdTask.timestamp = millis();

      if ( keyPress ==  START_KEY )

      {

        start = TRUE;

      }

     

      else if( keyPress == STOP_KEY )

      {

        LCD_Print_Line (0, (char*)"TONE STOPPED");

        LCD_Print_Line (1, lcd_msg);

        PWM1_Stop ();

        start = FALSE;

        index = 0u;

      }

     

      /* Play Tone*/

      if ( start == TRUE )

      {

        LCD_Print_Line (0, (char*)"PLAYING TONE:");

        LCD_Print_Line (1, tone_display[index]);

        PWM1_Stop ();

        PWM1_Init ((u32_t)saregamapa[index]);

        PWM1_Set_Duty (duty_cycle);

        PWM1_Start ();

        /* Force Update*/

        LCD_Update ();

        if ( index < SAREGAMAPA_SIZE )

          index++;

        else

          index = 0u;

      }

      LCD_Update ();

    }

  }

}

void Initialize_IO( void )

{

  // Select 16MHz Internal Oscillator

  OSCCONbits.IRCF = 0x07;             // From 1MHz to 16MHz

 

  Initialize_Keypad ();

  InitTimer0 ();

  LCD_Init ();

}

Please watch the following video for demo.

Download Source From GitHub