MSP430G2553 4x4矩阵键盘

#include <msp430.h>

typedef unsigned int uint;
typedef unsigned char uchar;

volatile uint t;
volatile uchar key;

void delay(){
    for(t = 1000; t > 0; t--);
}

void main(){
    WDTCTL = WDTPW + WDTHOLD;

    P1DIR = 0x0f;//LED
    P1OUT = 0x00;

    P2DIR = 0x0f;//0~3号为行输出，4~7号为列输入
    P2REN = 0xf0;//4~7号上拉
    P2OUT = 0xf0;

    P2IE = 0xff;//开启GPIO中断
    P2IES = 0xff;
    P2IFG = 0x00;

    __bis_SR_register(GIE);

}

#pragma vector=PORT2_VECTOR
__interrupt void Port_2(void){
    //P1OUT = 0xff;//test

    if(P2IN != 0xf0){
        delay();//软件消抖
        if(P2IN != 0xf0){
            switch(P2IN){//确定按键所在列:对应4~7号中的低电平位
                case 0xe0: key = 0; break;
                case 0xd0: key = 1; break;
                case 0xb0: key = 2; break;
                case 0x70: key = 3; break;
            }

            //先将所有行输出高电平并拉高所有列，然后逐行输出低电平
            //如果按键所在行输出低电平，则其所在列也会被拉低
            P2OUT = 0xfe; if(P2IN != 0xfe) { key += 0;  goto Cat; }
            P2OUT = 0xfd; if(P2IN != 0xfd) { key += 4;  goto Cat; }
            P2OUT = 0xfb; if(P2IN != 0xfb) { key += 8;  goto Cat; }
            P2OUT = 0xf7; if(P2IN != 0xf7) { key += 12; goto Cat; }
Cat:
            P1OUT = key;
            P2OUT = 0xf0;

        }
    }

    P2IFG &= 0;
}