IoT Projects - ESP8266 [CTC-3D Printer Upgrade]

Based on the previous blog posts on MQTT, ESP8266-01 and NodeMCU, I decided as mentioned before to upgrade my newly acquired 3D printer, a CTC-3D dual extruder printer.

The printer is awesome and while it already operates remotely via Octoprint on Cubietruck (see previous posts), I did find it useful to add a cooling system to it as well as some lighting inside the chassis, both to be remotely controlled as well.

This post is all about the lua scripts loaded to the ESP8266-01 wifi module, in order to achieve this.

First off, I had several issues with memory usage while using a stock nodeMCU firmware, meaning, a build containing all the available modules.

Trimming the fat from the firmware proved quite valuable in memory terms (check previous posts).

Then, moving on to the lua scripts, I managed to devise a basic management system where I can now update the wifi module configurations for WiFi and MQTT broker over the air, using the MQTT messaging system.

config_wifi.lua:

wifi_ssid='wifiHotspot'
wifi_pass='w1f1P4ss'

config_mqtt.lua:

mqtt_host='192.168.1.2'
mqtt_port=1883
mqtt_topic='topic-'..node.chipid() 

bootup.lua:
 

function bootup()
    wifi.setmode(wifi.STATION)
    wifi.sta.config(wifi_ssid,wifi_pass)
end

mqtt_connect.lua:



function mqttActivate()
            m:connect(mqtt_host, mqtt_port, 0, function(conn)
                print("connected to mqtt broker!")
                m:subscribe("/"..mqtt_topic,0, function(conn)
                 tmr.stop(3)
                 tmr.stop(2)
                end)
            end)
end

function mqttConnect()
  m = mqtt.Client(wifi.sta.getmac(), 120, "user", "password")
  m:lwt("/lwt", wifi.sta.getmac(), 0, 0)

  m:on("offline", function(con)
       tmr.alarm(2, 10000, 1, function()
        print ("reconnecting to mqtt broker...")
        mqttActivate()
       end)
  end)

  tmr.alarm(3, 10000, 1, function()
        print("connecting to mqtt broker...")
   mqttActivate()
  end)

  mqttParse()

end


mqtt_parse.lua:



function mqttParse()
  m:on("message", function(conn, topic, data)
    if data ~= nil then
      local i=1
      local offset=0
      while string.find(data,";") do

       field = string.sub(data, offset, string.find(data,":")-1)
       dataArray[field] = string.sub(data, string.find(data,":")+1, string.find(data,";")-1)
       data = string.sub(data, string.find(data, ";") + 1, string.len(data))

       i = i + 1
      tmr.wdclr()
      end

      if dataArray['type'] == 'config-update' then 
       confUpdate()
      elseif dataArray['type'] == 'gpio-control' then
       gpioControl()
      end
    end
  end)
end

config_update.lua:

function confUpdate()
 print('changing configuration for module: '..dataArray['setting'])

 if dataArray['setting'] == 'wifi' then
  file.open("config_wifi.lua", "w+")
  file.writeline('wifi_ssid=\''..dataArray['ssid']..'\'')
  file.writeline('wifi_pass=\''..dataArray['pass']..'\'')
  file.close()
 elseif dataArray['setting'] == 'mqtt' then
  file.open("config_mqtt.lua", "w+")
  file.writeline('mqtt_host=\''..dataArray['host']..'\'')
  file.writeline('mqtt_port='..dataArray['port'])
  file.writeline('mqtt_topic=\'topic-'..node.chipid()..'\'')
  file.close()
 end

 node.restart()

end

gpio_control.lua:



function gpioControl()
 print('setting GPIO pin: '..dataArray['gpio'])
 
 pin=0
 
 if dataArray['gpio'] == '0' then
  pin=3
 elseif dataArray['gpio'] == '2' then
  pin=4
 end

 if dataArray['state'] == 'on' then
  gpio.write(pin, gpio.HIGH)
 elseif dataArray['state'] == 'off' then
  gpio.mode(pin, gpio.INPUT)
 end

end

init.lua: 

require 'config_wifi'
require 'config_mqtt'
require 'bootup'
require 'mqtt_connect'
require 'mqtt_parse'
require 'config_update'
require 'gpio_control'

dataArray={}

bootup()

gpio.mode(3, gpio.INPUT)
gpio.mode(4, gpio.INPUT)

mqttConnect()

The WiFi module will try to connect the the WiFi network and from there, to the

MQTT broker. Once connected, it will register to a new topic based on its ID,

which you'll be able to catch in the MQTT broker log file.

You'll want to compile all scripts, except for config_wifi.lua, config_mqtt.lua

and init.lua.

I'm still learning Lua, hadn't used it before, which is to say that there's

definitely room for improvement here - however, as they stand, these

scripts do the job in allowing for remote, on demand control!

And finally, at this point, you'll be able to publish messages

to your MQTT broker server in order to operate your wifi module:

mosquitto_pub -h 192.168.1.2 -p 1883 -t /topic-12345678 -m 'type:gpio-control;gpio:0;state:on;'
mosquitto_pub -h 192.168.1.2 -p 1883 -t /topic-12345678 -m 'type:gpio-control;gpio:0;state:off;'
mosquitto_pub -h 192.168.1.2 -p 1883 -t /topic-12345678 -m 'type:gpio-control;gpio:2;state:on;'
mosquitto_pub -h 192.168.1.2 -p 1883 -t /topic-12345678 -m 'type:gpio-control;gpio:2;state:off;'

mosquitto_pub -h 192.168.1.2 -p 1883 -t /topic-12345678 -m 'type:config-update;setting:mqtt;host:192.168.1.3;port:1883;'
mosquitto_pub -h 192.168.1.2 -p 1883 -t /topic-12345678 -m 'type:config-update;setting:wifi;ssid:wifiHotspot;pass:w1f1P4ss;'