基于MSP430F249中P3.0-P3.7管脚设计4*4矩阵键盘代码

以下是基于MSP430F249中P3.0-P3.7管脚设计4*4矩阵键盘的代码：

#include "msp430f249.h"

#define ROWS 4
#define COLS 4

unsigned char KEYS[ROWS][COLS] = {
    {'1', '2', '3', 'A'},
    {'4', '5', '6', 'B'},
    {'7', '8', '9', 'C'},
    {'*', '0', '#', 'D'}
};

void init_keypad() {
    P3DIR = 0x0F;   // Set P3.0-P3.3 as output
    P3OUT = 0x0F;   // Set P3.0-P3.3 high
    P3REN = 0xF0;   // Set P3.4-P3.7 pull-up resistors
}

unsigned char read_keypad() {
    unsigned char row, col;
    for (row = 0; row < ROWS; row++) {
        P3OUT = ~(0x01 << row);  // Set one row low
        for (col = 0; col < COLS; col++) {
            if (!(P3IN & (0x10 << col))) {   // Check if key at row,col is pressed
                while (!(P3IN & (0x10 << col)));  // Wait until key is released
                P3OUT = 0x0F;   // Set all rows high
                return KEYS[row][col];  // Return key value
            }
        }
        P3OUT = 0x0F;   // Set all rows high
    }
    return 0;   // Return 0 if no key is pressed
}

void main() {
    WDTCTL = WDTPW | WDTHOLD;   // Stop watchdog timer
    init_keypad();  // Initialize keypad
    while (1) {
        unsigned char key = read_keypad();   // Read key value
        if (key != 0) {
            // Do something with key value
        }
    }
}

该代码中，`KEYS`数组存储了键盘上每个按键对应的字符。`init_keypad`函数初始化了MSP430F249的管脚，使得P3.0-P3.3输出低电平，P3.4-P3.7上拉，用于检测按键是否被按下。`read_keypad`函数扫描整个矩阵键盘，检测是否有按键被按下，返回对应的字符。`main`函数循环调用`read_keypad`函数读取按键值，并进行处理。