day30.buzzer蜂鸣器

第30节：buzzer蜂鸣器

1、编写编译运行测试
root@ubuntu:/home/linuxsystemcode/buzzer# cat buzzer.c
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

#define BUZZER_C 2

int main(int argc,char *argv[]){
        char *buzzer_ctl = "/dev/buzzer_ctl";

        int fd,ret,buzzer_c;

        buzzer_c = BUZZER_C;

        if(atoi(argv[1])>= buzzer_c){
                printf("argv[1] is 0 or 1\n");
                exit(1);
        }
        if((fd = open(buzzer_ctl,O_RDWR|O_NOCTTY|O_NDELAY))<0){
                pr