nodemcu的gpio相关操作

nodemcu的gpio设置为输入状态，好像默认是被上拉的，使用的时候注意功耗，当接地时候gpio能输出40ma的电流

gpio.read操作不管是被设置成输入还是输出，这个操作都是读取当前引脚的电平，跟输入输出无关

> gpio.mode(1, gpio.INPUT, gpio.PULLUP)
> = gpio.read(1) -- button not pressed
1
> = gpio.read(1) -- button is pressed
0
> = gpio.read(1) -- button not pressed
1
>



> gpio.mode(2,gpio.OUTPUT)
> gpio.write(2,gpio.HIGH) -- LED OFF
> gpio.write(2,gpio.LOW) -- LED ON


> gpio.mode(1, gpio.INT, gpio.PULLUP)
> gpio.trig(1, "both", function(level)
>> gpio.write(2, level)
>> end)
具体参考
http://blog.falafel.com/programming-gpio-on-the-esp8266-with-nodemcu/