【NanoPi NEO/Armbian】LinuxでLチカしてみよう (C言語プログラム制御編)

#!/bin/bash

if [ -d /sys/class/gpio/gpio6 ]
then
  echo 6 > /sys/class/gpio/unexport
fi
echo 6 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio6/direction
for  i  in  `seq  1  10`
do
  echo 1 > /sys/class/gpio/gpio6/value
  sleep 1
  echo 0 > /sys/class/gpio/gpio6/value
  sleep 1
done
echo 6 > /sys/class/gpio/unexport

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

int main()
{
    int fd = -1;
    int ret;
    int i;
    struct stat st = { 0 };

    // Unexport gpio6 if it exists.
    ret = stat("/sys/class/gpio/gpio6", &st);
    if(ret == 0) {
        fd = open("/sys/class/gpio/unexport",O_WRONLY);
        if(write(fd, "6", 1) != 1) {
            perror("write-1");
            exit(EXIT_FAILURE);
        }
        close(fd);
    }

    // Export gpio6.
    fd = open("/sys/class/gpio/export",O_WRONLY);
    if(write(fd, "6", 1) != 1) {
        perror("write-2");
        exit(EXIT_FAILURE);
    }
    close(fd);

    // Set direction to out.
    fd = open("/sys/class/gpio/gpio6/direction",O_WRONLY);
    if(write(fd, "out", 3) != 3) {
        perror("write-3");
        exit(EXIT_FAILURE);
    }
    close(fd);

    for(i = 0; i < 10; i++) {
        // Turn on the LED.
        fd = open("/sys/class/gpio/gpio6/value",O_WRONLY);
        if(write(fd, "1", 1) != 1) {
            perror("write-4");
            exit(EXIT_FAILURE);
        }

        sleep(1);

        // Turn off the LED.
        fd = open("/sys/class/gpio/gpio6/value",O_WRONLY);
        if(write(fd, "0", 1) != 1) {
            perror("write-5");
            exit(EXIT_FAILURE);
        }

        sleep(1);
    }

    // Unexport gpio6.
    fd = open("/sys/class/gpio/unexport",O_WRONLY);
    if(write(fd, "6", 1) != 1) {
        perror("write-1");
        exit(EXIT_FAILURE);
    }
    close(fd);

    exit(EXIT_SUCCESS);
}