temp-mqtt/application.lua

-- init mqtt client without logins, keepalive timer 120s
m = mqtt.Client("esp", 120)

-- init mqtt client with logins, keepalive timer 120sec
--m = mqtt.Client("", 120, "user", "password")

-- setup Last Will and Testament (optional)
-- Broker will publish a message with qos = 0, retain = 0, data = "offline"
-- to topic "/lwt" if client don't send keepalive packet
--m:lwt("/lwt", "offline", 0, 0)

m:on("connect", function(client) print ("connected") end)
m:on("offline", function(client) print ("offline") end)

-- Ice-boil calibration
-- function calibrate(temp)
--    local ReferenceLow = 0.01
--    local ReferenceHigh = 100
--    local ReferenceRange = ReferenceHigh - ReferenceLow
--    local RawLow = TEMP_ICE
--    local RawHigh = TEMP_BOIL
--    local RawRange = RawHigh - RawLow
--    local RawValue = temp
--    local CorrectedValue = (((RawValue - RawLow) * ReferenceRange) / RawRange) + ReferenceLow

--    if RawLow == nil or RawHigh == nil then
--       return temp
--    end

--    return CorrectedValue
-- end

ds_read_counter = 0

function ds_start_read()
   ds18b20.read(
      function(ind,rom,res,raw_temp,tdec,par)
         local mac = string.format("%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X",string.match(rom,"(%d+):(%d+):(%d+):(%d+):(%d+):(%d+):(%d+):(%d+)"))
         --local temp = calibrate(raw_temp)
         local temp = raw_temp
         print(ind,mac,res,temp,raw_temp)
         ok, json = pcall(sjson.encode, {rom=mac, res=res, temp=temp, raw=raw_temp, cnt=ds_read_counter})
         if ok then
            m:publish(MQTT_TOPIC, json, 0, 0, function(client)
                         print("sent "..json.." to "..MQTT_TOPIC)
                         ds_read_counter = ds_read_counter + 1
                         if file.open("counter.txt", "w") then
                            file.write(ds_read_counter)
                            file.close()
                         end
            end)
         else
            print("failed to encode!")
         end
    end,{});
end

function handle_mqtt_connected(client)
   print("mqtt connected")
   -- read last counter
   if file.open("counter.txt", "r") then
      ds_read_counter = file.read()
      file.close()
   end

   -- start temp reading
   ds18b20.setup(TEMP_PIN)
   ds_start_read()
   tmr.create():alarm(TEMP_RATE, tmr.ALARM_AUTO, function(timer) ds_start_read() end)
end

function handle_mqtt_error(client, reason)
  tmr.create():alarm(10 * 1000, tmr.ALARM_SINGLE, do_mqtt_connect)
end

function do_mqtt_connect()
  m:connect(MQTT_SERVER, handle_mqtt_connected, handle_mqtt_error)
end
do_mqtt_connect()