linux操作GPIO通用sysfs方法

echo N > /sys/class/gpio/export               #在gpio文件夹下导出编号为N的GPIO引脚
cat /sys/class/gpio/gpioN/direction           #查看方向
echo out > /sys/class/gpio/gpioN/direction    #设置为输出
echo in > /sys/class/gpio/gpioN/direction     #设置为输入
echo 0 > /sys/class/gpio/gpioN/value          #0/1 开关