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Appendix I
Page 406
#include <stdio.h>
#include <string.h>
int main(int argc, char** argv) {
int gpio = 4;
FILE* fd = fopen("/sys/class/gpio/export", "w");
fprintf(fd, "%d", gpio);
fclose(fd);
return 0;
}
Page 407
#include <stdio.h>
#include <string.h>
int main(int argc, char **argv)
{
int gpio = 4;
char buf[100];
FILE *fd = fopen("/sys/class/gpio/export", "w");
fprintf(fd, "%d", gpio);
fclose(fd);
sprintf(buf, "/sys/class/gpio/gpio%d/direction", gpio);
fd = fopen(buf, "w");
fprintf(fd, "out");
fclose(fd);
sprintf(buf, "/sys/class/gpio/gpio%d/value", gpio);
fd = fopen(buf, "w");
for (;;)
{
fd = fopen(buf, "w");
fprintf(fd, "1");
fclose(fd);
fd = fopen(buf, "w");
fprintf(fd, "0");
fclose(fd);
}
return 0;
}
