按照下面的命令点亮及熄灭LED
pi@raspberrypi:/sys/class/gpio $echo 26 > export
pi@raspberrypi:/sys/class/gpio $ cd gpio26
pi@raspberrypi:/sys/class/gpio/gpio26 $ ls
active_low device direction edge power subsystem uevent value
pi@raspberrypi:/sys/class/gpio/gpio26 $ cat direction
out
pi@raspberrypi:/sys/class/gpio/gpio26 $ cat value
1
pi@raspberrypi:/sys/class/gpio/gpio26 $ echo 0 >value
pi@raspberrypi:/sys/class/gpio/gpio26 $ cat value
0