nodemcu-firmware/lua_modules/dht22

DHT22 module

This module is compatible with DHT22 and DHT21.
Supports nodemcu with or without floating point.
No need to use a resistor to connect the pin data of DHT22 to ESP8266.

Example

PIN = 4 --  data pin, GPIO2

dht22 = require("dht22")
dht22.read(PIN)
t = dht22.getTemperature()
h = dht22.getHumidity()

if h == nil then
  print("Error reading from DHT22")
else
  -- temperature in degrees Celsius  and Farenheit
  -- floating point and integer version:
  print("Temperature: "..((t-(t % 10)) / 10).."."..(t % 10).." deg C")
  -- only integer version:
  print("Temperature: "..(9 * t / 50 + 32).."."..(9 * t / 5 % 10).." deg F")
  -- only float point version:
  print("Temperature: "..(9 * t / 50 + 32).." deg F")
  
  -- humidity
  -- floating point and integer version
  print("Humidity: "..((h - (h % 10)) / 10).."."..(h % 10).."%")
end

-- release module
dht22 = nil
package.loaded["dht22"]=nil

Functions

read

read(pin)
Read humidity and temperature from DHT22.

Parameters:

• pin - ESP8266 pin connect to data pin in DHT22

getHumidity

getHumidity()
Returns the humidity of the last reading.

Returns:

• last humidity reading in per thousand

getTemperature

getTemperature()
Returns the temperature of the last reading.

Returns:

• last temperature reading in 0.1ºC