arduino and dht11 output to lcd module in stock

Here is the simple code that will make it work correctly. I had the same issue and just figured it out. I put some comments about the changes I made and stuff I figured out…. Make sure you have the 3 libraries that are noted “#include”

This tutorial explains how to read or control modules using Arduino libraries which will be very important in any project, for it not only makes the code minimalistic, it also saves precious time.

The temperature and humidity sensor is a popular Arduino project because of its practicality and of its use of inexpensive modules. Keep in mind that this project is scalable and could also be used with a DHT22 for a much more accurate reading.

The DHT11 is a 4-pin sensor used to measure temperature and ambient humidity. This sensor can measure tempareture that ranges from 0°C - 50°C (± 2°C accuracy), and can measure ambient humidity that ranges from 20% RH - 90% RH (± 5% accuracy).

The DHT11 sensor included in the Arduino Upgraded Starter Kit comes with an ADC (Analog-to-Digital Converter) so the number of pins used will be lessend to three.

The 1602 LCD module is a 16-pin device used for display purposes. It is labeled 1602 because 16 characters can be displayed in a row, and this particular module has 2 rows. In total, it can display 32 characters at once.

The 1602 LCD Module included in the Arduino Upgraded Starter Kit already has a soldered I2C Module. This is especially helpful for those with no soldering tools and those who are saving space for the pins since using an I2C module lessens the number of pins used from sixteen pins (for parallel interface) to only four (for I2C)

The potentiometer (small blue screw knob) mounted on the I2C module is used to control the contrast of the display. Turning it full counter clockwise will result in an empty display so make sure to test this out when troubleshooting later on!

These modules would require long codes to make it function accordingly. However, there is also the option of using libraries to make these modules work with far lesser code.

Aftwerwards, you can verify if you had included the library by going back to Sketch -> Include Librarythen scroll down until you find the Contributed libraries block and saw your included user-library.

This is also a default Arduino function. Any commands set here will be looped indefinitely. The showTempHumi() function is called here and it"s designed to allow the sensor to read the temperature and humidity every two seconds.

This is a function that focuses on the display. Remember to always set the command lcd.clear() in a loop so the updated temperature and humidity would show and will not simply append after the last character on the previous set.

The dht is signalling the code that the user is going to call a function from this library. That part of the function is user-defined and could be named anyway the user wanted as highlighted below.

https://store.createlabz.com/blogs/createlabz-tutorials/humidity-and-temperature-sensing-using-dht11-and-20-4-lcd-display-on-arduino-uno-1?_pos=1&_sid=5bfdb52c8&_ss=r

In my photograph at the top of the post, you can see it is important to keep the build neat, as there are lots of connections which must be made. Neat work is facilitated is you use short jumper wires, instead of the big male to male wires. You can get a jumper wire set that will keep your work neat HERE.  I am not trying to sell you a bunch of junk, but as projects get more complicated, you really need to use the short straight wires, or your build will become a rat’s nest.

Hello friends! Welcome back to ElectroDuino. This blog is based on DHT11 Temperature and Humidity Sensor Arduino Code with LCD Display. Here we will discuss Introduction Temperature and Humidity Monitoring System, Circuit diagram, Working and DHT11 Temperature and Humidity sensor Arduino Code with LCD Display.

In the previous blog posts, we were learning about the “DHT11 Temperature and Humidity Sensor Module” and “Interfacing DHT11 with Arduino”. In this project, we will discuss how to make a Temperature and Humidity Monitoring System. Where we will print the Temperature and Humidity value on a 16×2 LCD display using DHT11 and Arduino. DHT11 is the cheapest humidity and temperature sensor, it provides high reliability and long-term stability output. This is a very small and portable Temperature and Humidity Monitoring system so we can use it at home, office, school, etc. places. It gives us the Temperature and Humidity value of around it 24 x7. Here we will build this system and learn how to write the DHT11 Temperature and Humidity Sensor Arduino Code with LCD Display.

Before writing the Arduino Code we need to install two Libraries in our Arduino IDE Software, one is ” dht.h ” DHT11 sensor Library and Another one is “LiquidCrystal.h” 16×2 LCD Display Library You can Download the Library file by click on the Download Button.

The DHT11 temperature and humidity sensor calibrated the digital signal output. Using specialized digital-signal and temperature and humidity sensing technology, it ensures high reliability and long-term stability. This sensor includes relative-type component and humidity measurement of the NTC temperature measurement component, and connects with excellent quality, fast response, anti-interference speed, a high performance 8-bit microcontroller capacity and cost effectiveness.

“Humidity” refers to the presence of water vapor in the atmosphere. Relative humidity is a measure of how close to saturation the air is with water vapor. If there is a lot of water vapor in the air, the humidity will be high.

Relative humidity (RH) is the ratio between the actual amount of water vapor present in the air and the maximum amount of water vapor that the air can hold at a given temperature.it is expressed as a percentage. At 100% RH, condensation occurs, and at 0% RH, the air is completely dry.

LCD stands for liquid crystal display. 16×2 LCD is named because; It has 16 columns and 2 rows. A lot of combinations like 8×1, 8×2, 10×2, 16×1 etc. are available. But the most commonly used is 16×2 LCD. So, it will have a total of 16×2 = 32 characters and each character will be composed of 5×8 pixel dots. For more information on LCD, please go LCD (Liquid Crystal) Display With Arduino Board.

Light emitted diodes (LED) are a semiconductor light source that emits light when the current flows through it. Electrons in semiconductor re-assemble electron holes and release energy in the form of photons. The color of light (consistent with photon energy) is determined by the energy required for electrons to cross the band gap of the semiconductor. In my previous tutorial, I explained How to blink led with Arduino board.

Pins 7-14 (Data Pins/D0) D7): These pins are used to send data to the display. In 4-wire mode, only four pins are attached to a microcontroller unit, 0 to 3, while in 8-wire mode, 8 pins are connected to microcontroller units 0 to 7.

Connect to the LED 220ohm resistor with the breadboard and attach to PIN6 and PIN7 of Arduino (digital PIN). And connect the small legs of both LED to the ground.

After connection, you must install the the LiquidCrystal library which has a folder you will place into your Arduino/libraries folder.Then write a simple program using the Arduino board in Arduino IDE software:

As a result, dht11 sensor data automatically captures data and your LCD will show humidity and temperature reading, And both LED lights will show the humidity and temperature shown in the following diagram:

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Welcome to ProteShea – in this project, we’re going to interface a DHT11 temperature and humidity sensor, and display the data on a 16×2 LCD. If you haven’t read

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Please see Project 9 on how to interface the 16×2 LCD in 4-bit mode. You should have pins 4, 6, and 11 – 14 of the LCD connected to Uno pins 2, 3, and 4 – 7, respectively.

The 20×4 LCD adds two extra rows and four extra columns per row compared to the 16×2 LCD. Similar to the 16×2, the 20×4 LCD uses the Hitachi controller so the commands and interfaces are the same. It also has the same 16-pin header, allowing you to unplug the 16×2 LCD and plug in the 20×4 without changing any wiring. The only thing we have to change is one line of code, lcd.begin(20, 4), which specifies the columns (first argument) and rows (second argument) of the LCD.

There are different types of DHT sensors such as the DHT11, DHT21, DHT22, DHT33, and DHT44. They all measure both temperature and humidity, but the difference lies mostly in their accuracy and sampling rate. For example, we show a side-by-side comparison in the table below of the two most popular DHT sensors, DHT11 and DHT22. The DHT22 has a better accuracy and range, but it has a slower sampling rate, it’s bigger in size, and double the cost of the DHT11.

To measure the temperature and humidity, a thermistor and a capacitive humidity sensor are used, respectively. The resistance of a thermistor changes with a change in temperature – as the temperature increases, the resistance decreases. For the humidity sensor, the resistance between the two electrodes changes with a change in humidity. Both of these changes in resistance are measured by the IC on the sensor and sent to the host via a 1-wire interface. Each sample consists of a 40-bit data packet.

We are using a 3-pin DHT11 sensor as shown in the image below. The pins are “+”, “OUT”, and “-.” The sensor can be supplied with both +5Vdc or +3.3Vdc – we’ll be supplying +5Vdc to it.

We are mounting the DHT11 sensor to the 2.54mm pitch section of Modulus with a right-angle (R/A) female header, as shown in the image below. Solder the 4-pin R/A female header to the edge of the board. Next, solder a 4-pin male header adjacent to the female header. Once you have the headers soldered on, flip the board over and make a solder bridge between the adjacent pins of the headers.

Wire-wrap the “+” pin to +5Vdc which is any of the pins in column 20 on the 4×26-pin breakout. Then wire-wrap the “-” pin to the GND vector just below the 4×26-pin breakout. Use a 12″ F/M jumper to connect the “OUT” pin to pin 8 of the Uno.

First, place the breadboard in the bottom storage compartment to limit the length of the jumper wires. You’ll need to supply +5V and GND to the power and ground rails on the breadboard by using the provided banana jack to test-lead clip cables. You will need two male header pins to mount the test-lead clips on the breadboard side. Plug the Type A side of the USB cable into USB1 receptacle and the Type B side into the Uno’s receptacle. Power up the FuelCan with the AC-DC power adapter.

Once the wiring is complete and the FuelCan is powered up, we can now load the sketch onto the Uno. The first sketch is used with the 16×2 LCD. The second sketch is used with the 20×4 LCD. The DHT11 sensor is sampled every two seconds since sampling faster causes errors.

Want to keep a log of the climate in your greenhouse, build a humidor control system, or track temperature and humidity data for a weather station project? AOSONG’s DHT11 or DHT22 Temperature and Humidity Sensor could be the perfect fit for you!

These sensors are factory-calibrated and do not require any external components to function. With just a few connections and a bit of Arduino code, you can begin measuring relative humidity and temperature right away.

They provide temperature and humidity readings accurate to within one decimal place, which is a plus. The only drawback is that they only provide new data every second or two, but for the price and performance, it’s hard to complain.

The DHT11 and the DHT22 are the two most widely used sensors in the DHTxx series. They look kind of the same and have the same pinout, but their specs are different.

Of the two, the DHT22 is more expensive and, undoubtedly, has better specifications. The DHT22 can measure temperatures from -40°C to +125°C with an accuracy of ±0.5°C, while the DHT11 can measure temperatures from 0°C to 50°C with an accuracy of ±2°C. In addition, the DHT22 sensor can measure relative humidity from 0 to 100% with an accuracy of 2-5%, while the DHT11 sensor can only measure relative humidity from 20 to 80% with an accuracy of 5%.

Despite the fact that the DHT22 is more accurate, precise, and capable of operating in a wider range of temperature and humidity, there are three areas where the DHT11 completely outperforms the DHT22 – It is more affordable, more compact, and has a higher sampling rate. DHT11 takes a reading once per second (or 1Hz sampling rate), while DHT22 takes a reading once every two seconds (or 0.5Hz sampling rate).

Despite these differences, the operating voltage of both sensors ranges from 3 to 5 volts, with a maximum current of 2.5mA (during conversion). The best part is that DHT11 and DHT22 sensors are swappable, which means that if you build your project with one, you can simply unplug it and replace it with another. Your code may need to be tweaked slightly, but the wiring remains the same!

The humidity sensing component has two electrodes with a moisture-holding substrate (usually a salt or conductive plastic polymer) in between. As the humidity rises, the substrate absorbs water vapor, resulting in the release of ions and a decrease in the resistance between the two electrodes. This change in resistance is proportional to the humidity, which can be measured to estimate relative humidity.

Technically, all resistors are thermistors in the sense that their resistance changes slightly with temperature, but the change is typically very small and difficult to measure.

Thermistors are designed so that their resistance changes dramatically with temperature (by 100 ohms or more per degree). The term “NTC” stands for “Negative Temperature Coefficient,” which means that resistance decreases as temperature rises.

The sensor also includes an 8-bit SOIC-14 packaged IC. This IC measures and processes the analog signal using stored calibration coefficients, converts the analog signal to digital, and outputs a digital signal containing the temperature and humidity.

VCC pin provides power to the sensor. Despite the fact that the supply voltage ranges from 3.3V to 5.5V, a 5V supply is recommended. With a 5V power supply, the sensor can be placed up to 20 meters away. With 3.3V supply voltage, the sensor can be placed up to 1 meter away; otherwise, the line voltage drop will cause measurement errors.

Connecting DHT sensors to Arduino is straightforward. They have fairly long 0.1′′-pitch pins, allowing them to be easily plugged into any breadboard. Connect the VCC pin to the Arduino’s 5V and the GND pin to ground. Finally, connect the Data pin to digital pin #8.

To ensure proper communication between the sensor and MCU, you must also add a 10K pull-up resistor between the Data line and VCC (to keep the signal HIGH). If you have a breakout board for the sensor, you do not need to add an external pull-up resistor, as it already contains one.

The DHTxx sensors have their own proprietary single-wire data transfer protocol. This protocol requires precise timing. We don’t have to worry too much about this, though, because we’ll be using the DHTlib library, which handles almost everything.

To install the library, navigate to Sketch > Include Library > Manage Libraries… Wait for the Library Manager to download the libraries index and update the list of installed libraries.

After installing the library, copy and paste this sketch into the Arduino IDE. The following test sketch will print the temperature and relative humidity values to the serial monitor. Try out the sketch, and then we’ll go over it in more detail.

The sketch begins by including the DHT library. Following that, we specify the Arduino pin number to which our sensor’s Data pin is connected and create a DHT object.

In the loop, we use the read22(dataPin) function to read the DHT22. This function takes as a parameter the sensor’s Data pin number. When working with DHT11, you must use the read11() function; to do so, you just need to uncomment the second line.

If you’re constructing your own incubator or a similar project, you’ll need a 16×2 character LCD rather than a serial monitor to display the current temperature and humidity levels. So, in this example, we’ll also connect the LCD to the Arduino in addition to the DHT11 and DHT22 sensors.

The sketch below will display the temperature and relative humidity values on the 16×2 character LCD. This sketch is similar to the previous one, except that the values are printed on the LCD.

This project shows the Date, Time, Temperature, Humidity and Alerts you when the temperature breaks a threshold and gives you a timestamp of highest temperature reached.

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/OpenWire.h:74: error: invalid in-class initialization of static data member of non-integral type "OpenWire::Object*"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/OpenWire.h:75: error: invalid in-class initialization of static data member of non-integral type "void (OpenWire::Object::*)(void*)"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/OpenWire.h: In member function "void OpenWire::CallbackPin::SetCallback(OpenWire::Object*, void (OpenWire::Object::*)(void*))":

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/Mitov_SimpleList.h:261: error: invalid in-class initialization of static data member of non-integral type "OpenWire::Pin**"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/Mitov_SimpleList.h:262: error: ISO C++ forbids in-class initialization of non-const static member "Mitov::SimpleList::_size"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/OpenWire.h:147: error: ISO C++ forbids in-class initialization of non-const static member "FIsConnected"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/OpenWire.h:211: error: ISO C++ forbids in-class initialization of non-const static member "FStarted"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/OpenWire.h:536: error: invalid in-class initialization of static data member of non-integral type "OpenWire::Object*"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/OpenWire.h:537: error: invalid in-class initialization of static data member of non-integral type "void (OpenWire::Object::*)(int, void*)"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/Mitov_SimpleList.h:261: error: invalid in-class initialization of static data member of non-integral type "OpenWire::Component**"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/Mitov_SimpleList.h:262: error: ISO C++ forbids in-class initialization of non-const static member "Mitov::SimpleList::_size"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/Mitov_SimpleList.h:261: error: invalid in-class initialization of static data member of non-integral type "OpenWire::Component**"

C:\Users\Patryk\Documents\Arduino\libraries\Mitov/Mitov_SimpleList.h:262: error: ISO C++ forbids in-class initialization of non-const static member "Mitov::SimpleList::_size"

Mitov::LiquidCrystalElementDefineCustomCharacter TArduinoLiquidCrystalElementDefineCustomCharacter1( LiquidCrystalDisplay1, 0, 12, 18, 18, 12, 0, 0, 0, 0 );

Arduino UNO - LCD display and DHT11 sensor with temperarure and humidity measurement. When there is no datafrom the DHT11 sensor, the buzzer will be activated.

Give your next Arduino project the ability to sense the world around it with the inexpensive DHT11 digital temperature & humidity sensor module from AOSONG.

The change in resistance between the two electrodes is proportional to the relative humidity. Higher relative humidity decreases the resistance between the electrodes, while lower relative humidity increases the resistance between the electrodes.

DHt11 also contains a NTC/Thermistor to measure temperature. A thermistor is a thermal resistor whose resistance changes drastically with temperature. The term “NTC” means “Negative Temperature Coefficient”, which means that the resistance decreases with increase of the temperature.

On the other side, there is a small PCB with an 8-bit SOIC-14 packaged IC. This IC measures and processes the analog signal with stored calibration coefficients, does analog to digital conversion and spits out a digital signal with the temperature and humidity.

The DHT11 sensors usually require external pull-up resistor of 10KΩ between VCC and Out pin for proper communication between sensor and the Arduino. However, the module has a built-in pull-up resistor, so you need not add it.

+ (VCC) pin supplies power for the sensor. 5V supply is recommended, although the supply voltage ranges from 3.3V to 5.5V. In case of 5V power supply, you can keep the sensor as long as 20 meters. However, with 3.3V supply voltage, cable length shall not be greater than 1 meter. Otherwise, the line voltage drop will lead to errors in measurement.

Connections are fairly simple. Start by connecting + (VCC) pin to the 5V output on the Arduino and connect – (GND) to ground. Finally, connect the Out pin to the digital pin #8.

DHT11 sensors have their own single wire protocol for transferring the data. This protocol requires precise timing. Fortunately, DHT Library was written to hide away all the complexities so that we can issue simple commands to read the temperature and humidity data.

The following test sketch will print the temperature and relative humidity values on the serial monitor. Try the sketch out; and then we will explain it in some detail.

The sketch starts by including DHT library and defining the Arduino pin number to which our sensor’s Out pin is connected. Then we create a DHT object to access special functions related to the library.

Sometimes you come up with an idea where you want to monitor temperature and humidity levels in your DIY incubator. Then you’ll probably need 16×2 character LCD to display prevailing conditions in your incubator, instead of a serial monitor. So, in this example, we’ll hook the LCD up to the Arduino along with the DHT11 module.

The following sketch will print the temperature and relative humidity values on the 16×2 character LCD. It uses the same code except we print values on LCD.

It’s a low cost digital temperature and humidity sensor module which based on the new DHT11 sensor. The Grove DHT11 sensor requires only one I/O pin for the communication with the master device.

The Grove DHT11 temperature & humidity sensor uses the upgraded version of DHT11. In this version, resistive humidity components is replaced by capacitive humidity components, temperature and humidity measurement ranges are wider and temperature resolution is higher.

Seeed Studio provides a nice open source library for their LCD module which can be installed from Arduino IDE library manager (Sketch —> Include Library —> Manage Libraries …, in the search box write “grove lcd” and install the one from Seeed Studio).

They (Seeed Studio) also provide a library for their Grove DHT11 sensor but I recommend to use the one given by Adafruit Industries which can be installed also through library manager (in the search box write “dht sensor” and choose the one written by Adafruit) or manually, download links are below:

I have the dht11 reading and printing to lcd and serial monitor.I have the dht11 controlling two relays one for temp and one for humidity.When the relay turns on the dht11 stops sending readings and freezes and stops reading? Any way I can fix that ?thanks

From what I’ve read from the datasheet it can’t be read from more than once every 2 seconds. Changing the delay to 2000 cleared the issue up right away for me

The output is to the serial monitor, unless you have connected an LCD. The video will show you how to open the serial monitor if you don’t already know how to.

A quick question tho, do you have a tutorial on how to connect this to a wireless transceiver?? also in theory could i connect more then one humidity detector to an arduino in order to detect humidity from more then one spot? Thank you again and i’ve subscribed!

Hi Jose, you can definitely connect more than one sensor to a single Arduino. You would basically duplicate the code, and have a separate pins read the data from each sensor. As for connecting them to a wireless tranceiver, I’m sure it’s possible, but you would probably need to use another microcontroller as a hub to transmit the data. I haven’t tried it yet though, so don’t take my word for it!

Hello, I built my first arduino project (measuring the room temperature and humidity with the DHT11) during Christmas holidays. The readings of the values were shown on the screen of my laptop. The measured room temperature was correct, but the measured humidity was much too low (about 20%RH). What can be the reason for ithe low humidity? And how can the sensor (if needed) be recalibrated?

I haven’t tried connecting multiple sensors, but it should be fairly easy. You would just duplicate the code and use a separate pin to read the data for each sensor

Probably not, since the signal is at the same voltage as Vcc. If you swap the Vcc and signal pins, the output will just read -999.00 for temp and humidity.

vcc is the left one, signal the middle one and ground is the round one, in case of a 3 pin DHT11. the diagram above is not right. i was getting the same problem here.

IN MY CASE IN THE DHT-11 BOARD WRONG RESISTOR WAS SOLDERED, WITHOUT KNOWING TAT I HAD TRIED ALL STUFF, GIVEN 10K PULL UP ADDITIONALLY.. DIDN’T WORKED FINALLY TRACED THE RESISTANCE BETWEEN PINS IT WAS 5 OHMS.. THEN BACK TRACED & REMOVED TAT & PULLED UP WITH 10k SOLVED MY ISSUE.. GUESS U TOO HAVE THE SAME ISSUE.. JUST CHK OUT..

The diagram is correct for most three pin DHT11 modules. Depending on the manufacturer, the pins on the PCB might be different though. The pins should be labelled with S for signal and “-” or “GND” ground.

Then i understood, that the breadboard has not 2 power circuits (top and bottom), but four (top left, top right, bottom left, bottom right). This is the thing which was never said on youtube)

See the section “Output Humidity and Temperature Readings to an LCD Display” on a desktop… If you are viewing it on mobile, the full code might not display. Hope this helps

Can you guys help me in this. All I want is to design a circuit that could predict a rainfall or water and send a message to the user to his phone.Also keeping in mind about the humidity and temperature factors.

It sounds like you want to control the heater with the DHT11 and have the readings output to an LCD too… You can use the DHT11 to control the signal to a 5V relay, similar to what’s done in this article: https://www.circuitbasics.com/build-an-arduino-controlled-power-outlet/

Then you just need to add the code to initialize the LCD, include the LiquidCrystal library, and change the “serialprint()” functions to “lcd.print(). We have another article on setting up an LCD on the Arduino if you need help with it: https://www.circuitbasics.com/how-to-set-up-an-lcd-display-on-an-arduino/

i didnt have any trouble interfacing the arduino, lcd and the dht11 sensor and my codes were quite right since when i run it, nothing’s odd in the output. but when i connect the relay,in which an ac device is connected, as an output that turns on after a couple of minutes, the temperature and humidity dislayed on the lcd becomes odd, like chinese and numbers, after some time. i checked my codes but i cant figure out whats wrong with it.

please help me.. i won’t get Alarm temperature and humidity..and show in lcd display 16×2.. and changeing temperature, humidity alarm set point HOW IS DO… PLEASE HELP ME.

So curiously, I had already downloaded and installed the latest version of DHTLib (v0.1.21) versus the older version (v0.1.14) that is provided here. And I kept getting 0.00 values for the temp and humidity readings as Alex reported on April 20, 2016 in a posting above. I scratched my head for a while until I remembered I had the newer version of the library installed. So I removed that, installed the older v0.1.14 version, and bam, lo and behold, I started getting real values back. So this may be the same problem that Alex had, too.

I’ve looked at the brief changelog history in dht.cpp file, and I’m seeing no obvious reason that might allow v0.1.14 to work, but not the newer v0.1.21. Anyone have thoughts about this?

Any comments about DHTLib v0.1.14 vs. v0.1.21, and why this simple Arduino sketch works in the former, but not the latter? The brief history in the cpp file header for v0.1.21 looks like it took care of a few issues so my first instinct is to use that, but again, it results in all zero readings. Anyway, if no comments, well, I’ll have to take a look through the diffs between the two versions to see what might be causing the issue.

vcc is the left one, signal the middle one and ground is the right one, in case of a 3 pin DHT11. the diagram above is not right. i was getting the same problem here.

The diagram is correct, but your particular DHT11 could have a different pinout depending on the manufacturer. The DHT11 I used is from Keyes, what type do you have?

Are you using the four pin DHT11? If so you’ll need to put a 10K Ohm resistor between the Signal line and Vcc. I just added another diagram to the post to make it a bit clearer. That may be causing your issue.

Thanks a lot, may you please help me out, I am using a Mega 2560 with a DHT11 sensor, my problem is that both temperature and humidity reading is just being reed as 0.00 and they are not changing. What might i be doing wrongly, I have even tried the code that accompanies these tutorials

This seems like a really simple setup, but I’ve been having a lot of trouble setting this up. Have there been changes to this library? I have downloaded it, but arduino still refuses to recognize dht or any of the related functions, like temperature/humidity. It had a lot of trouble with line 3, dht DHT;. Any advice?

Yes, the library was updated recently (v. 0.1.21) and doesn’t seem to work. If you download the zip file I put in the post, it should work. It’s the older version 0.1.14.

Hi, you mentioned you added a piece of code to show the “degree” symbol,” lcd.print((char)223)”, can you tell me if the number 223 is from the ASCII table.

vcc is the left one, signal the middle one and ground is the right one, in case of a 3 pin DHT11. the diagram above is not right. i was getting the same problem here.

i am doing fire alarm system using dht and lcd and GSM sim800l how can i make argument to send message from gsm if the sensor reading is higher that the set temp and how to declare it thanks for your response

After uploading a code my dht-11 keeps reading zero ‘0’ for both humidity and temperature as the output on my serial monitor. please what could be the problem?

I am very happy to inform you that I fixed successfully the temp and humidity project with LCD display. I would like to subscribe but cannot find the link.Many thanks

C:\Users\mhine\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.2.0\cores\esp8266/Arduino.h:227:63: error: cannot convert ‘volatile uint32_t* {aka volatile unsigned int*}’ to ‘volatile uint8_t* {aka volatile unsigned char*}’ in initialization

Hi. I have the same issue with the same board. Did you get it to succeed in the end? I would be interested, but I feel that it may be a compatibility issue with a 3rd-party board. I have tried the exact code with other Arduinos that I have and it works just fine.

I get this same error when I try to use the Arduino 101 instead of the Uno. I think the library doesn’t support the board. I would try finding a different DHT library, there are several others out there.

I Have issues with the Arduino recognizing the file dht.h. Was told no such file exist, meanwhile I have uploaded the zip file into the Arduino IDE, which showed in the file directory.

Did you use the library in the zip file from the post, or did you download it from the Arduino.cc page? Version 0.1.21 has some issues and doesn’t appear to work. The zip file in the post is version 0.1.14, and it does work. Also, are you using the Uno, or another board? I couldn’t get the library to work on my Arduino 101…

In this language, does declaring an object variable (as in “dht DHT;”) automatically instantiate it? I am more used to other languages that would need to follow the declaration with something along the lines of “DHT = new dht(params, for, constructor);” Does this normally go without saying in C++, or is this something the Arduino environment automatically adds at the preprocessing** stage?

**: If not “preprocessing,” then whatever else Arduino parlance calls the process of converting/expanding the “Processing” (??) or “Wiring” (???) code into standard C/C++ ????

hey can you pls help me how to use rf module with the above project. i am using two arduino uno, DHT11, LCD, RF transmitter and receiver. please can u give me a code to display temperature and humidity on the receiver side lcd…

to start the cummunication the ardduino will give LOW to the data line,after the dht finished the transmition of data,the line will return to HIGH,IS THAT CORRECT???

Thanks for the mod, skyfox66. Being in America among the holdouts, I am of course still using degrees F. After days of struggling and searching I finally got this combination of parts and code to work right. (After I found this website).

I connected the LCD and the DHT11 and copied and pasted the code. It uploaded and then I look at my LCD and all I see are white boxes on the top of the display. Can anyone help me?

I copied this exactly and got it to display temperature and humidity, but it flashes -999 for temp and -999 for humidity every other second. For example, it will display correct readings for one second, then the -999 for both readings the next second.. Flashing between the two. Any ideas why it might be doing this. I have been playing with the code, rechecking pins, etc, but I cant seem to pinpoint the problem. Any input is appreciated.

hello, i need some help, i want code for, if i m sending message from mobile (e.g. ABC) to arduino via gsm module then the values of temperature and humidity receiving specific number

I have arn Arduino y module that I am using to trgger an extractor fan in a shower. I was wondering whether this humidity sensor could be used to simply close the 5v circuit so teh fan runs on until teh humidity is below a set vaue. Is that possible simply?

Hi.recently i conduct sensor circuitry.in source code,i notice that it use \xF8 to display temperature in degree celcius.what is the function of that?

I followed the instructions exactly, wiring was good, code was an exact replica of that given. Everything was correct, but I got -999 error message every time. I was using a three pin sensor, triple checked my wiring against the diagram. I increased the delay time to 3000ms. I was definitely using the correct older version of the library. After throwing out the sensor thinking it faulty, I have since discovered that the diagram above is does not apply to every dht11, that there are some where the pins are in a different order.

What does this mean? in every other arduino program I can find that uses additional libraries, the library is called first, then the code goes straight on to initialising the variables and describing the setup. I have not been able to find any other mention of the library name mentioned twice like this. A few people have asked about this, with no answers given. I cant even search for it because I dont know what to search by.

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Clear, informative and knowledgeable. Moisture from the air collects on the film and causes changes in the voltage levels between the two plates. This change is then converted into a digital measurement of the air’s relative humidity after taking the air temperature into account.

You will get 100% humidity if you put the sensor in water and it works. Use an SHT31-D breakout board to detect humidity and temperature. I’m sure you didn’t mean you are going to submerge the sensor. The SHT31-D is more accurate and easier to install and costs about the same as the DHT11 /22 both of which really aren’t accurate at all.

i have changed the sensor, checked voltages at each junction,switched pull up resistor, included the exact library available here but couldn’t get the accurate result,

Ine is set up exactly as you show. I get -999.00 for both humidity and temperature. I have 2 different sensors (both DHT11) and I get the same readings. I even set this up on an RPI 3B+ and the readings were similar. 1.0 temp and humidity. What am I doing wrong?

I’m a bit new to audrino and i started my first project. I found that this tutorial was the most comprehensive out there, which is awesome. One thing that i’m running into a bit of issue on is that im an “400 invalid_request” while attempting to import the DTH library. I was wondering if you could provide a little assistance to get pass this issue. Please see the full error message below.

I’m wondering if there’s a way to have this working intermittently? I want to moderate the humidity levels in food containers to prevent mould. If this was running off a battery would it last long enough?

I can not keep my display from blinking the temp and humidity values. It displays the value but blinks back and forth to -999.00. Thanks for the help I’m new

Your so awesome dude. I owe you a lot! Thanks for the tutorial dude. you’d help many people. keep going! God bless more power. Im from philippines ^_^

Still getting -999.00 on both temperature and humidity with LCD. If I connects ONLY DTH11 to Arduino with serial monitor it works fine, BUT if I connect it to LCD as described above it shows -999.00 In both LCD and serial monitor. It looks like it disables the DTH11 when connected to LCD. It does not work with dely(2000); or any other value.

i don’t know why but the LCD shows me white circles and within them the text is written also the temp and humidity are a constant 0 even with the serial monitor

It’s good idea for projects. I am thinking of building my own weather unit soon. Please can someone help me with a simulation circuit that will show the response graphs of dht11 for temperature and humidity

How would you configure Celsius to Fahrenheit when doing the LCD version? I read others commenting how with out the LCD but not with the code for using the LCD.

I’m looking to couple this humidity sensor with a 5V relay to actuate a small on/off valve depending on the humidity level. Essentially, I’d like valve to open when the humidity reading from the sensor goes above, say, 75%, and closes when the reading goes below 60%. Do you have any recommendations?

I am a hobbyist and has certain experience in electronics and wish to adopt programming. So kindly some one can help me to achieve the above goal with codes and probable sketches for the connections.Hope to receive a reply in this respect from your side.

HELLO, thank you for the big assistance. I’d like to share to u the screenshoot of my serial monitor output… Atleast let me show how it looks like & help me to debug. Big thanks to you

You have to adjust the wait time to less to count for the fact that the sensor Only gives an output for a small amount of time so play around with that to get it to work

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If you do not know about DHT11, DHT22 temperature sensor and LCD (pinout, how it works, how to program ...), learn about them in the following tutorials:

The above code also work for Arduino Nano. A grandfather, who learns through this tutorial to guide his grandchild has tested this code with Arduino Nano and send us the result like below:

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In the above code, we have used two libraries, the LiquidCrystal and DHT library. The LiquidCrystal comes pre-installed with Arduino. But the DHT library from Adafruit has to be installed manually. You can see the DHT11 Humidity and Temperature Sensor with Arduino tutorial where we have explained how to install the DHT library. These two libraries header files, the LiquidCrystal.h and DHT.h, are included in the program above.

In order to use the DHT library feature, we have to specify which DHT sensor we are using. The DHT library supports DHT11, DHT22 and DHT21 sensors. So to specify that we are using DHT11 we use the define DHTType DHT11 statement. Next we have to specify which microcontroller pin will be connected to the data pin of the sensor and as shown above in dht11 interfacing with arduino wiring diagram, we have to pin 7 and this is done using the define DHTPIN 7 statement.

Down the code we have used the LiquidCrystal lcd() and dht() function to initialize the LCD library and DHT library by specifying which pins are used for each case.

In the setup() function, we initialize and start the DHT sensor using the dht.begin() and the LCD using the lcd.begin() function which requires to specify number of columns(16) and rows(2). After this, we use the print() function to print string "DHT11" on the LCD. The setCursor(0, 1) function puts the string following it("Humidity/Temp.") in the 2nd line of the LCD.

In the loop() function, we first use delay() function to wait for 2 second for DHT sensor and LCD to initialize. Next we have used the readHumidity() and readTemperature() methods of object dht to read humidity and temperature and have stored them in the float variable H and T. The next if statement is to check whether the data read from the sensor are valid or not. If the data read is not valid then error message is shown otherwise the next statement following it are executed. If there is no error, the last statements are just there to print the read values onto the LCD screen.

The LCD will light up only when the all my components are located in the bottom right of the breadboard. Why am I not able to use the entire breadboard for my circuit?