#include "msp430g2231.h"
 
//Definition of the notes' frequecies in Hertz.
#define c 261
#define d 294
#define e 329
#define f 349
#define g 391
#define gS 415
#define a 440
#define aS 455
#define b 466
#define cH 523
#define cSH 554
#define dH 587
#define dSH 622
#define eH 659
#define fH 698
#define fSH 740
#define gH 784
#define gSH 830
#define aH 880
 
/* This two functions stop the main thread for a certain number of milli -or- microseconds.
   They are based on trial and error, but they work fine for the out-of-the-box Launchpad board.
   TI should really add this types of functions as default, just like Arduino does :) .
*/
void delay_ms(unsigned int ms )
{
    unsigned int i;
    for (i = 0; i<= ms; i++)
       __delay_cycles(500); //Built-in function that suspends the execution for 500 cicles
}
 
void delay_us(unsigned int us )
{
    unsigned int i;
    for (i = 0; i<= us/2; i++) 
       __delay_cycles(1);
}
 
//This function generates the square wave that makes the piezo speaker sound at a determinated frequency.
void beep(unsigned int note, unsigned int duration)
{	
    int i;  
    long delay = (long)(10000/note);  //This is the semiperiod of each note. 
    long time = (long)((duration*100)/(delay*2));  //This is how much time we need to spend on the note.
    for (i=0;i<time;i++)    
    {    
        P1OUT |= BIT2;     //Set P1.2...
        delay_us(delay);   //...for a semiperiod...
        P1OUT &= ~BIT2;    //...then reset it...
        delay_us(delay);   //...for the other semiperiod.
    }  
    delay_ms(20); //Add a little delay to separate the single notes
}
 
//This is the Imperial March code. 
//As you can see, there are lots of beeps at different frequencies and durations, and some delays to separate the various bits of this wonderful song.
void play()
{
    beep(a, 500);
    beep(a, 500);
    beep(a, 500);
    beep(f, 350);
    beep(cH, 150);  
    beep(a, 500);
    beep(f, 350);
    beep(cH, 150);
    beep(a, 650);
 
    delay_ms(150);
    //end of first bit   
 
    beep(eH, 500);
    beep(eH, 500);
    beep(eH, 500);   
    beep(fH, 350);
    beep(cH, 150);
    beep(gS, 500);
    beep(f, 350);
    beep(cH, 150);
    beep(a, 650);
 
    delay_ms(150);
    //end of second bit...  
 
    beep(aH, 500);
    beep(a, 300);
    beep(a, 150);
    beep(aH, 400);
    beep(gSH, 200);
    beep(gH, 200); 
    beep(fSH, 125);
    beep(fH, 125);    
    beep(fSH, 250);
 
    delay_ms(250);
 
    beep(aS, 250); 
    beep(dSH, 400); 
    beep(dH, 200);  
    beep(cSH, 200);  
    beep(cH, 125);  
    beep(b, 125);  
    beep(cH, 250);  
 
    delay_ms(250);
 
    beep(f, 125);  
    beep(gS, 500);  
    beep(f, 375);  
    beep(a, 125);
    beep(cH, 500);
    beep(a, 375);  
    beep(cH, 125);
    beep(eH, 650);
 
    //end of third bit... (Though it doesn't play well)
    //let's repeat it
 
    beep(aH, 500);
    beep(a, 300);
    beep(a, 150);
    beep(aH, 400);
    beep(gSH, 200);
    beep(gH, 200);
    beep(fSH, 125);
    beep(fH, 125);    
    beep(fSH, 250);
 
    delay_ms(250);
 
    beep(aS, 250);  
    beep(dSH, 400);  
    beep(dH, 200);  
    beep(cSH, 200);  
    beep(cH, 125);  
    beep(b, 125);  
    beep(cH, 250);      
 
    delay_ms(250);
 
    beep(f, 250);  
    beep(gS, 500);  
    beep(f, 375);  
    beep(cH, 125);
    beep(a, 500);   
    beep(f, 375);   
    beep(cH, 125); 
    beep(a, 650);   
    //end of the song
 
}
 
int main( void )
{
    WDTCTL = WDTPW + WDTHOLD; //Disable Watchdog Timer
    P1DIR|=BIT2;              // P1.2 output
    while(1)
    {
	play();              
	delay_ms(2000);      //Add a 2 sec. delay to avoid replaying right after the end.
    }
}