开启红色：echo 1 > /sys/class/gpio/gpio2/value
关闭红色：echo 0 > /sys/class/gpio/gpio2/value
开启绿色：echo 1 > /sys/class/gpio/gpio3/value
关闭绿色：echo 0 > /sys/class/gpio/gpio3/value
开启蓝色：echo 1 > /sys/class/gpio/gpio4/value
关闭蓝色：echo 0 > /sys/class/gpio/gpio4/value
通过搭配红绿蓝能显示更多颜色