ESP8266 WiFi – Temperatuur en luchtvochtigheid sensor DHT 11

Op deze pagina vind je een voorbeeld om via de ESP-01 module een DHT11/22 sensor te gebruiken via de GPIO pinnen met de firmware NodeMCU.

Hardware

BESTEL NU!

Met deze module kun je de temperatuur en luchtvochtigheid meten, hij is door de fabrikant al behoorlijk geijkt, eventuele aanpassingen (bijvoorbeeld ijken) kunnen softwarematig gedaan worden.

Werkt op: 5V.
Temperatuur bereik: 0 – +50 ºC.
Temperatuur nauwkeurigheid: ±2,0 ºC.
Vochtigheid bereik: 20-95% RH.
Vochtigheid nauwkeurigheid: ±5,0% RH.
Response tijd: < 5 sec.

Pinout

Pin:	Functie:
01	+5V
02	Data
03	NC (niet aangesloten)
04	GND

De Keyes versie (met weerstand):

[table “6” not found /]

LET OP: Er zijn ook andere versie in omloop, controleer altijd de pinout of raadpleeg de handleiding!

Wat heb je nodig?

1) ESPlorer IDE

2) firmware:

Je zal zelf een firmware moeten proberen (20150107 wordt aanbevolen), ook wordt de float versie aanbevolen, dit is wat ik getest heb:
WERKT – nodemcu_20150107.bin
WERKT – nodemcu_float_0.9.5_20150318.bin
WERKT NIET – nodemcu_float_0.9.6-dev_20150704.bin

Sluit de DHT11/22 module aan op volgens onderstaand schema:

ESP8266 ESP-01 GPIO DHT11 schema

Upload deze “library” code als dht_lib.lua

Tip: Download de code en sla het op als bestand, gebruik de “Upload…” knop in ESPlorer.

-- ***************************************************************************
-- for communication of DHT sensor only
-- DHT module for ESP8266 with nodeMCU floating point
-- Written by Javier Yanez
-- but based on a script of Pigs Fly from ESP8266.com forum
-- MIT license, http://opensource.org/licenses/MIT
-- ***************************************************************************
 
local moduleName = ...
local M = {}
_G[moduleName] = M
 
local humidity
local temperature
 
function M.read(pin)
  local checksum
  local checksumTest
  humidity = 0
  temperature = 0
  checksum = 0
 
  -- Use Markus Gritsch trick to speed up read/write on GPIO
  local gpio_read = gpio.read
 
  local bitStream = {}
   for j = 1, 40, 1 do
    bitStream[j] = 0
  end
  local bitlength = 0
 
  -- Step 1:  send out start signal to DHT22
  gpio.mode(pin, gpio.OUTPUT)
  gpio.write(pin, gpio.HIGH)
  tmr.delay(100)
  gpio.write(pin, gpio.LOW)
  tmr.delay(20000)
  gpio.write(pin, gpio.HIGH)
  gpio.mode(pin, gpio.INPUT)
 
  -- Step 2:  DHT22 send response signal
  -- bus will always let up eventually, don't bother with timeout
  while (gpio_read(pin) == 0 ) do end
  local c=0
  while (gpio_read(pin) == 1 and c < 500) do c = c + 1 end
  -- bus will always let up eventually, don't bother with timeout
  while (gpio_read(pin) == 0 ) do end
  c=0
  while (gpio_read(pin) == 1 and c < 500) do c = c + 1 end
 
  -- Step 3: DHT22 send data
  for j = 1, 40, 1 do
    while (gpio_read(pin) == 1 and bitlength < 10 ) do
      bitlength = bitlength + 1
    end
    bitStream[j] = bitlength
    bitlength = 0
    -- bus will always let up eventually, don't bother with timeout
    while (gpio_read(pin) == 0) do end
  end
   hum=" "
   tem=" "
   chk=" "
  --DHT data acquired, process.
  for i = 1, 16, 1 do
  hum=hum.." "..tostring(bitStream[i])
  tem=tem.." "..tostring(bitStream[i+16])
    if (bitStream[i] > 3) then
      humidity = humidity + 2 ^ (16 - i)
    end
    if (bitStream[i + 16] > 3) then
      temperature = temperature + 2 ^ (16 - i)
    end
  end
  for i = 1, 8, 1 do
  chk=chk.." "..tostring(bitStream[i+32])
    if (bitStream[i + 32] > 3) then
      checksum = checksum + 2 ^ (8 - i)
    end
  end
    checksumTest = (bit.band(humidity, 0xFF) + bit.rshift(humidity, 8) + bit.band(temperature, 0xFF) + bit.rshift(temperature, 8))
  checksumTest = bit.band(checksumTest, 0xFF)
 
  if temperature > 0x8000 then
    -- convert to negative format
    temperature = -(temperature - 0x8000)
  end
 
  -- conditions compatible con float point and integer
  if (checksumTest - checksum >= 1) or (checksum - checksumTest >= 1) then
    humidity = nil
  end
  --print("checksum ", checksum)
  --print("checksumTest ", checksumTest)
  --print("humidity - timing of bits ",hum)
  --print("temperat - timing of bits ",tem)
  --print("checksum - timing of bits ",chk)
end
 
function M.getTemperature()
  return temperature
end
 
function M.getHumidity()
  return humidity
end
 
return M

100

101

102

103

104

105

106

107

108

-- ***************************************************************************

-- for communication of DHT sensor only

-- DHT module for ESP8266 with nodeMCU floating point

-- Written by Javier Yanez

-- but based on a script of Pigs Fly from ESP8266.com forum

-- MIT license, http://opensource.org/licenses/MIT

-- ***************************************************************************

local moduleName = ...

local M = {}

_G[moduleName] = M

local humidity

local temperature

function M.read(pin)

local checksum

local checksumTest

humidity = 0

temperature = 0

checksum = 0

-- Use Markus Gritsch trick to speed up read/write on GPIO

local gpio_read = gpio.read

local bitStream = {}

for j = 1, 40, 1 do

bitStream[j] = 0

end

local bitlength = 0

-- Step 1: send out start signal to DHT22

gpio.mode(pin, gpio.OUTPUT)

gpio.write(pin, gpio.HIGH)

tmr.delay(100)

gpio.write(pin, gpio.LOW)

tmr.delay(20000)

gpio.write(pin, gpio.HIGH)

gpio.mode(pin, gpio.INPUT)

-- Step 2: DHT22 send response signal

-- bus will always let up eventually, don't bother with timeout

while (gpio_read(pin) == 0 ) do end

local c=0

while (gpio_read(pin) == 1 and c < 500) do c = c + 1 end

-- bus will always let up eventually, don't bother with timeout

while (gpio_read(pin) == 0 ) do end

c=0

while (gpio_read(pin) == 1 and c < 500) do c = c + 1 end

-- Step 3: DHT22 send data

for j = 1, 40, 1 do

while (gpio_read(pin) == 1 and bitlength < 10 ) do

bitlength = bitlength + 1

end

bitStream[j] = bitlength

bitlength = 0

-- bus will always let up eventually, don't bother with timeout

while (gpio_read(pin) == 0) do end

end

hum=" "

tem=" "

chk=" "

--DHT data acquired, process.

for i = 1, 16, 1 do

hum=hum.." "..tostring(bitStream[i])

tem=tem.." "..tostring(bitStream[i+16])

if (bitStream[i] > 3) then

humidity = humidity + 2 ^ (16 - i)

end

if (bitStream[i + 16] > 3) then

temperature = temperature + 2 ^ (16 - i)

end

for i = 1, 8, 1 do

chk=chk.." "..tostring(bitStream[i+32])

if (bitStream[i + 32] > 3) then

checksum = checksum + 2 ^ (8 - i)

end

checksumTest = (bit.band(humidity, 0xFF) + bit.rshift(humidity, 8) + bit.band(temperature, 0xFF) + bit.rshift(temperature, 8))

checksumTest = bit.band(checksumTest, 0xFF)

if temperature > 0x8000 then

-- convert to negative format

temperature = -(temperature - 0x8000)

end

-- conditions compatible con float point and integer

if (checksumTest - checksum >= 1) or (checksum - checksumTest >= 1) then

humidity = nil

end

--print("checksum ", checksum)

--print("checksumTest ", checksumTest)

--print("humidity - timing of bits ",hum)

--print("temperat - timing of bits ",tem)

--print("checksum - timing of bits ",chk)

end

function M.getTemperature()

return temperature

end

function M.getHumidity()

return humidity

end

return M

Gebruik de volgende code om de temperatuur en luchtvochtigheid weer te geven, sla het op als dhtread.lua:

Let op!: Geef hierin ook aan of het een DHT11 of DHT22 sensor betreft.

sensorType="dht11"  -- set sensor type dht11 or dht22
 
    PIN = 4 --  data pin, GPIO2
    humi=0
    temp=0
    --load DHT module for read sensor
function ReadDHT()
    dht=require("dht_lib")
    dht.read(PIN)
    chck=1
    h=dht.getHumidity()
    t=dht.getTemperature()
    if h==nil then h=0 chck=0 end
    if sensorType=="dht11"then
        humi=h/256
        temp=t/256
    else
        humi=h/10
        temp=t/10
    end
    fare=(temp*9/5+32)
    print("Humidity:    "..humi.."%")
    print("Temperature: "..temp.." deg C")
    -- release module
    dht=nil
    package.loaded["dht_lib"]=nil
end
ReadDHT()

sensorType="dht11" -- set sensor type dht11 or dht22

PIN = 4 -- data pin, GPIO2

humi=0

temp=0

--load DHT module for read sensor

function ReadDHT()

dht=require("dht_lib")

dht.read(PIN)

chck=1

h=dht.getHumidity()

t=dht.getTemperature()

if h==nil then h=0 chck=0 end

if sensorType=="dht11"then

humi=h/256

temp=t/256

else

humi=h/10

temp=t/10

end

fare=(temp*9/5+32)

print("Humidity: "..humi.."%")

print("Temperature: "..temp.." deg C")

-- release module

dht=nil

package.loaded["dht_lib"]=nil

end

ReadDHT()

Om de sensor uit te lezen start het bestand dhtread.lua

dofile("dhtread.lua")

resultaat:

Humidity: 39%
Temperature: 21 deg C

1 2	Humidity: 39% Temperature: 21 deg C

bron:
scottsnowden.co.uk

Zoeken

ESP8266 WiFi – Temperatuur en luchtvochtigheid sensor DHT 11 (NodeMCU)

Hardware

Pinout