DHT11 sensor data to Thingspeak using a Wemos D1

In this example we will connect a DHT11 sensor to our Wemos D1, we will then send the temperature and humidity values to thingspeak.

Wemos_D1_ESP8266

DHT11 digital temperature and humidity sensor is a composite Sensor contains a calibrated digital signal output of the temperature and humidity. Application of a dedicated digital modules collection technology and the temperature and humidity sensing technology, to ensure that the product has high reliability and excellent long-term stability. The sensor includes a resistive sense of wet components and an NTC temperature measurement devices, and connected with a high-performance 8-bit microcontroller.

Typically a DHT11 can be bought in a basic breakout board format but can be bought as a standalone part as well, here is a picture of a typical breakout board, this board holds the sensor and a resistor, the resistor is connected between Vdd (3v3) and the signal pin on the board.

dht11 breakout

If you do not use a module like the one aboveyou can build a similar circuit on a breadboard. Here is a typical schematic, which is basically what the breakout above actually is

 

Dht11_application

You will connect the Gnd of the module (DHt11) to a Gnd on your Wemos board, connect 5v or Vdd of the module (DHt11) to a 3v3 connection on your Wemos and the Sig pin (data pin on the DH11) goes to whatever input you decide to use on your Wemos, in the code below you can see this as

#define DHTPIN 2

 

You will now need to create a new account at thingspeak – https://thingspeak.com. Once done create a new channel and add two new fields, one will hold the temperature reading and the other will hold the humidity reading from our DHT11. This should look something like this

thingspeak channel
thingspeak channel

Parts List

Here are the parts I used

 

Name Links
Wemos Mini
DHT11
Connecting cables

Code

You will need an api key from thingspeak.

 

#include <DHT.h>
#include <ESP8266WiFi.h>

// replace with your channel’s thingspeak API key and your SSID and password
String apiKey = "thingspeak api key";
const char* ssid = "ssid name";
const char* password = "ssid password";
const char* server = "api.thingspeak.com";

#define DHTPIN D2
#define DHTTYPE DHT11 

DHT dht(DHTPIN, DHTTYPE);
WiFiClient client;

void setup() 
{
Serial.begin(115200);
delay(10);
dht.begin();

WiFi.begin(ssid, password);

Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) 
{
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");

}

void loop() 
{

float h = dht.readHumidity();
float t = dht.readTemperature();
if (isnan(h) || isnan(t)) 
{
Serial.println("Failed to read from DHT sensor!");
return;
}

if (client.connect(server,80)) {
String postStr = apiKey;
postStr +="&field1=";
postStr += String(t);
postStr +="&field2=";
postStr += String(h);
postStr += "\r\n\r\n";

client.print("POST /update HTTP/1.1\n");
client.print("Host: api.thingspeak.com\n");
client.print("Connection: close\n");
client.print("X-THINGSPEAKAPIKEY: "+apiKey+"\n");
client.print("Content-Type: application/x-www-form-urlencoded\n");
client.print("Content-Length: ");
client.print(postStr.length());
client.print("\n\n");
client.print(postStr);

Serial.print("Temperature: ");
Serial.print(t);
Serial.print(" degrees Celsius Humidity: ");
Serial.print(h);
Serial.println("Sending data to Thingspeak");
}
client.stop();

Serial.println("Waiting 20 secs");
// thingspeak needs at least a 15 sec delay between updates
// 20 seconds to be safe
delay(20000);
}

 

Results

If you login to your thingspeak account you can view live channel data

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47 COMMENTS

  1. Hi!

    I’m new in Arduino programming and I try to make wemos sensor data, but i have KY-015 whit dht11 sensor, but vhen I connect it and upload your code it cant read from sensor. Can you help me whit changes in sketch that I need to make?

    Thanks!

    • In the ARduino IDE, when you open the Serial monitor at 115200 do you see any output. The Serial.print lies are effectively only useful for debug. The key one is Serial.println(“Failed to read from DHT sensor!”);. All I could recommend is that you double check your wiring in particular the data connection which in this case is the pin with the S beside it

  6. […] Ahora toca el programita que hay que subir. Tendremos que cambiar el pin donde conectamos el dht, en mi caso he usado el D5, (no olvidar sustituir el 2 por D5, no vale solo 5). Además hay que añadir la api key de thingspeak y el usuario y contraseña de tu wifi. El programa que me ha funcionado lo he sacado de: http://www.esp8266learning.com/dht11-sensor-data-to-thingspeak-using-a-wemos-d1.php […]

  7. […] Ahora toca el programita que hay que subir. Tendremos que cambiar el pin donde conectamos el dht, en mi caso he usado el D5, (no olvidar sustituir el 2 por D5, no vale solo 5). Además hay que añadir la api key de thingspeak y el usuario y contraseña de tu wifi. El programa que me ha funcionado lo he sacado de: http://www.esp8266learning.com/dht11-sensor-data-to-thingspeak-using-a-wemos-d1.php […]

    • Some things to check

      Are you using the correct com port in the Arduino IDE for the board
      If you disconnect any external devices connect to the device does the upload work then?
      Try another USB cable – I have had issues with cheaper and nasty ones (its not common though)
      If you had another board you could try that with nothing attached.

      Basically you are just ruling things out – incorrect settings, power issues, faulty hardware

  10. Hi, okay I know I’m so annoying but, I changed dht11 for dht22 they are more accur..
    But now, in log:

    Connect to: Applepen
    ……
    Wi-Fi connected

    Exception (0):
    epc1=0x40106da9 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

    ctx: cont
    sp: 3ffef650 end: 3ffef880 offset: 01a0

    >>>stack>>>
    3ffef7f0: 0000ffff 00ffff00 3ffee6ac 40203966
    3ffef800: 3fffdad0 00000000 3ffee6ac 402039bc
    3ffef810: 7fc00000 00000000 3ffee6ac 40202426
    3ffef820: 3ffe8580 3ffe8360 3ffee824 40203d88
    3ffef830: 3fff018c 40202edc 3ffee824 40203dac
    3ffef840: 3ffe8364 3ffee728 3ffee824 40202375
    3ffef850: feefeffe feefeffe feefeffe 3ffee850
    3ffef860: 3fffdad0 00000000 3ffee848 4020455c
    3ffef870: feefeffe feefeffe 3ffee860 40100718
    <<<stack<<<

    ets Jan 8 2013,rst cause:2, boot mode:(3,6)

    load 0x4010f000, len 1384, room 16
    tail 8
    chksum 0x2d
    csum 0x2d
    v60000318
    ~ld

    and then again, and again.. it can be some problem with router? I used router for Xiaomi, but now I have Linksys wrt54gl.

    but anyways.. thank you for any help 🙁

  11. Hello guys… this was my first project with the wemos and I woundering how to do an offset on the sensor.

    The sensor is showing way off the real temperature so I whant to calibrate it with an offset.

  12. What DHT-library did you use? The one I have installed has got a file named dht.h instead of DHT.h. After I have changed the sketch at 2 lines (“#include ” and “dht dht(DHTPIN, DHTTYPE);”), I got these errors:

    Blink:11: error: ‘DHT11’ was not declared in this scope
    #define DHTTYPE DHT11
    ^
    /tmp/arduino_modified_sketch_951828/Blink.ino:13:17: note: in expansion of macro ‘DHTTYPE’
    dht dht(DHTPIN, DHTTYPE);
    ^
    etc.

    Thank you!

      • #include

        #define DHTPIN D2
        #define DHTTYPE DHT11

        DHT dht(DHTPIN, DHTTYPE);

        void setup()
        {
        Serial.begin(115200);
        delay(10);
        dht.begin();

        }

        void loop()
        {

        float h = dht.readHumidity();
        float t = dht.readTemperature();
        if (isnan(h) || isnan(t))
        {
        Serial.println(“Failed to read from DHT sensor!”);
        return;
        }

        Serial.print(“Temperature: “);
        Serial.print(t);
        Serial.print(” degrees Celsius Humidity: “);
        Serial.print(h);
        delay(1000);

        }

        • Sorry I didn’t add a reply (see below for my first reaction). In the meantime I noticed that “D2” doesn’t work for my, neither does “2”. I have to use “5” (and put the wire in connection “D15/SCL/D3”). With this change I shall try your sketch again tomorrow.
          The values for temperature en humidity are both too low, resp. 2 degrees celcius and 20%. Is there a simple solution for that?

  19. Hi. I’m using Wemos D1 mini and Wemos DHT shield. It shows me wrong temperature and humidity. I’ve set it to DHT11, but it don’t shows real values. It’s just a little bit.
    About 5°C and 20% humadity.

  20. I am using a D1R1 board, same as pictured above, but am unable to make this work on D2, although I can make it work on D5. I tried an even simpler program, doing a digitalRead on pin 2 (with D2 tied to a pushbutton to ground and a pullup resistor) and it seems to read the value at boot, but doesn’t show changes. Same for D3.
    I’m compiling with board set to WeMos D1(retired).
    Any thoughts on what’s going on?

  22. Thanks for this mate it works perfectly, the only thing i had to change was the ssid name/password and the D2 pin to D8 (one im using for the dht11). Massively appreciate it, hope you’re still creating!

  23. after the compile, the error message as follows. What is wrong?. Please help…

    In file included from d:\Arduino\libraries\DHT_sensor_library\DHT_U.cpp:22:0:
    d:\Arduino\libraries\DHT_sensor_library\DHT_U.h:25:29: fatal error: Adafruit_Sensor.h: No such file or directory
    #include
    ^
    compilation terminated.
    Multiple libraries were found for “DHT.h”
    Used: d:\Arduino\libraries\DHT_sensor_library
    Not used: d:\Arduino\libraries\Grove_Temperature_And_Humidity_Sensor
    Using library DHT_sensor_library at version 1.3.0 in folder: d:\Arduino\libraries\DHT_sensor_library
    Using library ESP8266WiFi at version 1.0 in folder: C:\Users\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.4.1\libraries\ESP8266WiFi
    exit status 1
    Error compiling for board WeMos D1 R2 & mini.

  24. Hi, Please Help me

    I have tried this code with WeMos D1 R2 and all I am getting is “Failed to read from DHT sensor!”

    My DHT11 sensor is working well for Arduino UNO board but fails on WeMos D1 R2, please help me to fix this issue

  25. Great example! It took me 5 minutes to register at thingspeak.com and 5 minutes to upload the code into my Wemos D1; little change – DHT22 insteasd of DHT11 as the latter is not so accurate. Thanks a lot + wishes for new creations!

  26. Hello!

    For a school project we need to get data from a temperature/humidity sensor (DHT11) and a dust sensor written to a SD card. Our group like to go further so we bought the Wemos and make it upload the data from the DHT11 to thingspeak to our own website.
    We got it to work, but we can’t get the dust sensor to work correctly, it’s a Shinyei PPD42. We can’t get the script working correctly.
    Can anybody help us?

    Thanks in advance!