In this very simple example, I will setup a NodeMCU to connect to my MQTT broker and light its LED depending on received messages. This gives a very simple IOT device to test the MQTT protocol.
Controlling NodeMCU’s LED through MQTT
Path to “Magic button” S01E01
This is the code to blink a LED on a GPIO on an ESP8266-1 loaded with NodeMCU. What is of particular interest is the GPIO0 and GPIO2 values.
GPIO0=3 GPIO2=4 pin = GPIO0 gpio.mode(pin, gpio.OUTPUT) lighton=0 tmr.alarm(0,1000,1,function() if lighton==0 then lighton=1 gpio.write(pin, gpio.HIGH) -- 512/1024, 50% duty cycle else lighton=0 gpio.write(pin, gpio.LOW) end print(lighton) end)