MSP430求助。。。我是新手。。用的是g2553

#include"msp430.h" //包含头文件，系统自动匹配对应芯片的头文件

int n = 3;

void main(void)
{
	WDTCTL = WDTPW+WDTHOLD; //关看门狗

	P1DIR |= BIT0; //P1.0 作输出口
	P1DIR |= BIT6; //p1.6作输出口
	P1OUT &= ~BIT0;
	P1OUT &= ~BIT6;

	P1IE |=  BIT3;                            // P1.3 interrupt enabled
	P1IES |= BIT3;                            // P1.3 Hi/lo edge
	P1REN |= BIT3;							// Enable Pull Up on SW2 (P1.3)
	P1IFG &= ~BIT3;                           // P1.3 IFG cleared

	__bis_SR_register(LPM3_bits + GIE);

	while(1)
	{
		switch (n)
		{
		case 0:
		{
			P1OUT |= BIT0;
			P1OUT &= ~BIT6;
			break;
		}
		case 1:
		{
			P1OUT |= BIT6;
			P1OUT &= ~BIT0;
			break;
		}
		case 2:
		{
			P1OUT &= ~(BIT0 + BIT6);
			break;
		}
		case 3:
		{
			P1OUT ^= BIT0|BIT6;
			__delay_cycles(1000000);
			break;
		}
		}
	}

}

// Port 1 interrupt service routine
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
	unsigned int i;
	unsigned char PushKey;

	PushKey = P1IFG & BIT3;
	for(i=3000;i>0;i--)
	{
		__no_operation();
	}
	if((P1IN & PushKey)==PushKey)
	{
		P1IFG = 0;
		return;
	}

	if(PushKey & BIT3)
	{

		n++;
		if(n == 4)
			n = 0;
		__bic_SR_register_on_exit(LPM3_bits);
	}
	P1IFG &= ~BIT3;                           // P1.3 IFG cleared
}