MSP430 G2553 LaunchPad GPIO中断

P1、P2端口上的每个管脚都支持外部中断。P1端口的所有管脚都对应同一个中断向量（Interrupt Vector），类似的，P2端口的所有管脚都对应另一个中断向量；通过PxIFG寄存器来判断中断来源于具体哪个管脚。

相关的寄存器如下表所示。

Register	Short Form	Register Type	Initial State
Interrupt Flag	PxIFG	Read/write	Reset with PUC
Interrupt Edge Select	PxIES	Read/write	Unchanged
Interrupt Enable	PxIE	Read/write	Reset with PUC

PxIFG：中断标志，1表示有中断事件待处理

PxIES：中断边沿选择，0表示上升沿触发，1表示下降沿触发

PxIE：GPIO中断使能，0表示禁用，1表示使能

程序示例

利用板上S2按键控制LED1灯闪烁，每按下一次，LED1灯闪烁一次。该程序还缺少按键消抖的功能。（G2 LaunchPad Rev1.5上P1.3没有连接电容及上拉电阻）

 #include "io430.h"

 #define LED1 BIT0
 #define PUSH2 BIT3

 //function declarations
 void delay(void);

 void main(void)
 {
     // Stop watchdog timer to prevent time out reset
     WDTCTL = WDTPW + WDTHOLD;

     //set P1.3 to input with pullup
     P1OUT = ;
     P1OUT |= PUSH2; //initialize the pullup state
     P1REN |= PUSH2; //enable internal pullup

     //set P1.0 to output
     P1DIR |= LED1; //P1.0 out to LED1, P1.3 remains input for PUSH2 button

     //set the interrupt registers
     P1IES |= PUSH2; //select high -> low transition
     P1IFG &= ~PUSH2; //clear the flag for P1.3 before enabling the interrupt,
     // to prevent an immediate interrupt
     P1IE |= PUSH2; //enable interrupt for P1.3

     __enable_interrupt(); //turn on the interrupts

     while()
     {
     }

 }

 void delay(void)
 {
     volatile unsigned int i;
     for(i = ; i < ; i++);
 }

 //interrupt service routines
 #pragma vector  = PORT1_VECTOR
 __interrupt void P1_ISR(void)
 {
     if((P1IFG & PUSH2) == PUSH2)
     {
         P1IFG &= ~PUSH2; //clear the interrupt flag

         P1OUT |= LED1; //turn on LED1
         delay();
         P1OUT &= ~LED1; //turn off LED1
     }
     else
     {
         P1IFG = ;
     }
 }