#include<stdlib.h>
#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>

int main(int argc,char *argv[])
{
    int ret;
    int fd;
    char buffer[100];
    ssize_t bytes_read;
    ret = access("/sys/class/pwm/pwmchip0/pwm0",F_OK);
    if(ret != 0 )
    {
        fd = open("/sys/class/pwm/pwmchip0/export",O_WRONLY);
        write(fd,"0",1);
        close(fd);
    }

    fd = open("/sys/class/pwm/pwmchip0/pwm0/capture",O_RDONLY);
    if(fd == -1)
    {
	    perror("failed to open capture file");
	    return EXIT_FAILURE;
    }

    bytes_read = read(fd,buffer,sizeof(buffer)-1);
    if(bytes_read == -1)
    {
       perror("failed to read capture value");
       close(fd);
       return EXIT_FAILURE;
    }
    buffer[bytes_read] = '\0';

    printf("capture value:%s\n",buffer);
    
    close(fd);  
    return 0;

}