#include <msp430.h> 
#include "common.h"

const word onecycle = 30;//         1/32768
word diff;
byte compareDone;
word distance;
word cnt;


#pragma vector = TIMER0_B0_VECTOR
__interrupt void Timer_B (void) 
{
	__no_operation();
	if(TB0IV==TB0IV_TBIFG) //Check if Timer1 overflow caused the interrupt
	{
			TB0CTL&=~(TBIFG); //Reset overflow flag
	}
	else //If Capture module caused the interrupt
	{
		diff=TB0CCR1; //Save the value of Timer1 at the time of first key press
		TB0CCTL1&=~(CCIFG); //Reset Capture Flag
		compareDone = 0x02;
		TB0CTL&=~(TBIFG); //Reset overflow flag
	}
}





/*
/////////////////////////////////////////////////////////////////////////////////////////////////////////
///////
// Function             : M A I N    R O U T I N E
// Programmer           : musa melih çulha            	Start Date              : 
// Modified by          : yyyyyyyyy             	Last Edit               : 
// Description          : 
// History              :                             
//
/////////////////////////////////////////////////////////////////////////////////////////////////////////
///////
*/
void main(void)
{
	word mesafe = 0;
	byte reset;
	word negEdge;
	word posEdge;

	WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer
	
	//Configuring Trigger pin as output P1.0
	P1DIR |= BIT2;
	P1OUT &= ~BIT2;

	
	//Configuring echo pin as input P1.7
	P2DIR &= ~BIT0;
	P2SEL0 |= BIT0;	//1
	P2SEL1 &= ~BIT0;//0
	P2OUT &= ~BIT0; // Set output to low
	__delay_cycles(18000); // low for 18 ms
//	P2REN |= BIT0;
	

//	SYSCFG3 = 0x02;
	PM5CTL0 &= ~LOCKLPM5;
	SYSCFG3 = 0x02;
	
	P1DIR |= BIT7;            // P1.0 and P1.6 pins output the rest are input 
	
	TB0CCTL0 = CCIE;                        // CCR0 interrupt enabled
	TB0CCR0 = 10500;	// for 10ms	// timer freq = (1/Xtal)*TA0CCR0 second
//	TB0CTL = TBSSEL_2 | MC_1 | TBCLR;       // SMCLK, upmode, clear TAR

	TB0CCTL1 |= CM_2+CCIS__CCIA+SCS+CAP+CCIE; //Setup Timer1 with synchronous capture on both edges, connected to Vcc
	//and generate interrupt on capture
	TB0CTL |= TBSSEL_2+MC_1+TBIE; //Setup Timer1 to run on SMCLK, UP mode and generate interrupt on overflow
	

	diff = 0;
	compareDone = 0;
	distance = 0;
	cnt = 0;

	__enable_interrupt(); //Enable maskable interrupts
	__bis_SR_register( GIE);


	//Trigger pin high for more than 20us
	P1OUT |= BIT2;
	__delay_cycles(20);
	P1OUT &= ~BIT2;


	__no_operation();


	for(;;)
	{
		P1OUT |= BIT2;		
		__delay_cycles(20);
		P1OUT &= ~BIT2;			
		

		__enable_interrupt(); //Enable maskable interrupts
		__bis_SR_register( GIE);
		__delay_cycles(100000);
		__no_operation();
	}
	
	
	

	while(1)
	{
		//Perform calculation to find distance in cm.
		__no_operation();
		if(compareDone == 0x02)
		{
			__disable_interrupt();
			TB0CTL = TBCLR;
			diff = negEdge - posEdge;
			distance = (onecycle * diff) / 58;

			mesafe = distance;
			//After calculation restart the operation
			compareDone = 0x00;
			__enable_interrupt();
			P1OUT |= BIT2;
			__delay_cycles(20);
			P1OUT &= ~BIT2;
			TB0CTL = TBSSEL__ACLK | MC__CONTINUOUS;
			reset = 0;
		}
		__delay_cycles(800000);
		reset ++;
		
		//If calculation fails restart the operation again
		if(reset == 10)
		{
			__disable_interrupt();
			TB0CTL = TBCLR;
			compareDone = 0x00;
			__enable_interrupt();
			P1OUT |= BIT2;
			__delay_cycles(20);
			P1OUT &= ~BIT2;
			TB0CTL = TBSSEL__ACLK | MC__CONTINUOUS;
			reset = 0x00;
		}

	}
}