ESP-01 + DHT22: send temperature and humidity to influxdb

user_dht22_influxdb.lua

--
-- send DHT22 sensor values to influxdb database
--

LOCATION = "upstairs.bathroom"

-- #################################

INFLUXDB_HOST = "sun.thomo.de"
INFLUXDB_DB = "lhw5"

-- DHT_PIN = 3 -- GPIO0
DHT_PIN = 4 -- GPIO2

-- #################################

FLOAT_FIRMWARE = (1/3) > 0
CRLF = "\r\n"

wifi.setmode(wifi.STATION)
-- set wifi config via console
-- wifi.sta.config(WIFI_SSID,WIFI_PASSWORD)
wifi.sta.autoconnect(1)

function convertValue(val,val_dec)
  local result
  if FLOAT_FIRMWARE then
    -- Float firmware using this example
    result = string.format("%.1f",val)
  else
    -- Integer firmware using this example
    result = string.format("%d.%03d",val,val_dec)
  end
  return result
end

function buildTempHumiDataLine(format, temp, humi)
  return string.format(format, "temperature", temp)..
    "\n"..
    string.format(format, "humidity", humi)
end

function buildStatusLine(format, msg)
  return string.format(format, "status", msg)
end

function getDHT22Content(location)
  local result

  local dataPattern = "%s"..
    ",location="..location..
    ",sensor=dht22"..
    " value=%s"

  local status, temp, humi, temp_dec, humi_dec = dht.read(DHT_PIN)

  if status == dht.OK then
    local tValue = convertValue(temp, temp_dec)
    local hValue = convertValue(humi, humi_dec)
    result = buildTempHumiDataLine(dataPattern, tValue, hValue)
  elseif status == dht.ERROR_CHECKSUM then
    result = buildStatusLine(dataPattern, "\"Checksum\",ec=1" )
  elseif status == dht.ERROR_TIMEOUT then
    result = buildStatusLine(dataPattern, "\"Timeout\",ec=2" )
  else
    result = buildStatusLine(dataPattern, "\"Unknown\",ec=999")
  end

  return result
end

function buildPostRequest(host, db, data)
  return "POST /write?db="..db.." HTTP/1.1"..CRLF..
    "Host: "..host..CRLF..
    "Connection: close"..CRLF..
    "Content-Type: application/x-www-form-urlencoded"..CRLF..
    "Content-Length: "..string.len(data)..CRLF..
    CRLF..
    data
end

function sendData()
  local content = getDHT22Content(LOCATION)

  socket = net.createConnection(net.TCP, 0)
  socket:on("receive",function(sck, c) print(c) end)
  socket:connect(8086, INFLUXDB_HOST)
  socket:on("connection", function(sck)
    local post_request = buildPostRequest(INFLUXDB_HOST, INFLUXDB_DB, content)
    sck:send(post_request)
  end)
end

-- ###### MAIN #########

tmr.alarm(0, 20 * 1000, tmr.ALARM_AUTO, sendData)

fix to post string values in case of error