button_test.c

2440 下的5*5按键驱动程序.请参看具体代码内容.

/*按键测试
* date:Dec.02,2008
* author: daihj07@thu
* v1.0
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>

int main(int argc, char **argv)
{
    int i;
    int ret;
    int fd;
    int press_cnt[5];
    
    fd = open("/dev/buttons", 0);  // 打开设备
    if (fd < 0) {
        printf("Can't open /dev/buttons\n");
        return -1;
    }

    // 这是个无限循环，进程有可能在read函数中休眠，当有按键被按下时，它才返回
    while (1) {
        ret = read(fd, press_cnt, sizeof(press_cnt));
        if (ret < 0) {
            printf("read err!\n");
            continue;
        } 
        for (i = 0; i < sizeof(press_cnt)/sizeof(press_cnt[0]); i++) {
            // 如果被按下
            if (press_cnt[i])
                printf("Key row: %d col: %d has been pressed\n", i+1, press_cnt[i]);
        }
    }
    
    close(fd);
    return 0;    
}