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）

 1 #include "io430.h"
 2 
 3 #define LED1 BIT0
 4 #define PUSH2 BIT3
 5 
 6 //function declarations
 7 void delay(void);
 8 
 9 void main(void)
10 {
11     // Stop watchdog timer to prevent time out reset
12     WDTCTL = WDTPW + WDTHOLD;
13     
14     //set P1.3 to input with pullup
15     P1OUT = 0;
16     P1OUT |= PUSH2; //initialize the pullup state
17     P1REN |= PUSH2; //enable internal pullup
18     
19     //set P1.0 to output
20     P1DIR |= LED1; //P1.0 out to LED1, P1.3 remains input for PUSH2 button
21     
22     //set the interrupt registers
23     P1IES |= PUSH2; //select high -> low transition
24     P1IFG &= ~PUSH2; //clear the flag for P1.3 before enabling the interrupt,
25     // to prevent an immediate interrupt
26     P1IE |= PUSH2; //enable interrupt for P1.3
27     
28     __enable_interrupt(); //turn on the interrupts
29     
30     while(1)
31     {
32     }
33 
34 }
35 
36 void delay(void)
37 {
38     volatile unsigned int i;
39     for(i = 0; i < 50000; i++);
40 }
41 
42 //interrupt service routines
43 #pragma vector  = PORT1_VECTOR
44 __interrupt void P1_ISR(void)
45 {
46     if((P1IFG & PUSH2) == PUSH2)
47     {
48         P1IFG &= ~PUSH2; //clear the interrupt flag
49         
50         P1OUT |= LED1; //turn on LED1
51         delay();
52         P1OUT &= ~LED1; //turn off LED1
53     }
54     else
55     {
56         P1IFG = 0;
57     }
58 }