arduino dht11 lcd display brands

I am going to show you how I made a temp and humidity sensor with an Arduino Uno. My end goal is to make one with an Attiny84 and etch a PCB for it. While I do have the parts and pieces to do this, the weather outside is not cooperating. It is hard to etch a board in my garage at less than 10 degrees Fahrenheit. That will be a different instructable for a later date.

All parts can be purchased at sparkfun or adafruit. Or you can do as I do and salvage as much as you can from old devices.Arduino (I used an UNO R3, but 5V any will work)BreadboardDHT11 temperature and humidity sensor10k ohm potentiometer16x2 LCD screentactile buttonUSB A-B cablePower BankJumper Wires

The LCD display I am using was recovered from an old fire alarm annunciator panel. Pins 15 & 16 are located before Pin 1 and instead of Pin 16 being Gnd, it is actually 5v and Pin 15 is Gnd. Please double check your own display and make sure your pins are correct. As my display pinout is most likely different from almost everybody else, I have made the Fritzing schematic with the "standard" display instead of my exact pinout.

DTH11Pin1 --> 5v and 10k ohm resistorPin2 --> Arduino Pin8 and 10k ohm resistorPin3 --> no connectionPin4 --> Gnd16x2 LCD ScreenPin1 --> GndPin2 --> 5vPin3 --> 10k ohm potentiometer wiper pin ( middle pin. the other two pins on the POT go to 5v and Gnd)Pin4 --> Arduino Pin12Pin5 --> GndPin6 --> Arduino Pin11Pin7 --> no connectionPin8 --> no connectionPin9 --> no connectionPin10 --> no connectionPin11 --> Arduino Pin5Pin12 --> Arduino Pin4Pin13 --> Arduino Pin3Pin14 --> Arduino Pin2Pin15 --> 5vPin16 --> Tactile button (other side of tack button goes to Gnd)

Now, this project uses a DHT11 temperature and humidity sensor with the three pin but you can also use any other sensor the changes in the code should be as per the model. I have used Arduino UNO for this project.

Lastly, the code part where the real understanding begins. So, basically I have used two libraries one for the sensor and the other for the LCD 1602 I2C display. Then let us start:

I wrote the whole code together hope you may not find it too difficult.void setup() {dht.begin();// initialize the sensorlcd.backlight();// turn on lcd backlightlcd.init();// initialize lcd}void loop() {lcd.clear();lcd.setCursor(0,0);// set the cursor on the first row and columnlcd.print("Humidity=");lcd.print((float)dht.readHumidity());//print the humiditylcd.print("%");lcd.setCursor(0,1);//set the cursor on the second row and first columnlcd.print("Temp=");lcd.print((float)dht.readTemperature());//print the temperaturelcd.print("Celsius");delay(2000);lcd.clear();}

I strongly recommend the Arduino Web Editor as you do not need to download any additional libraries since it is pre-included but if you do not use the web editor and use the software instead you may need to make slight changes but the main part remains the same.

This is a simple temperature and humidity monitor device made by use of components like lcd keypad shield , dht11 sensor and arduino mega. The temperature accuracy of dht11 not up to the point but it’s good.

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

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?

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.

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.

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

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.

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?

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

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…

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.

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.

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 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

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.

The DHT11 temperature and humidity sensor is a nice little sensor that provides digital temperature and humidity readings. It’s really easy to set up, and only requires one wire for the data signal. These sensors are popular for use in remote weather stations, soil monitors, and home automation systems.

Programming the DHT11 and connecting it to a Raspberry Pi is pretty simple too. In this tutorial, I’ll show you how to connect the DHT11 to the Raspberry Pi and output the humidity and temperature readings to an SSH terminal or to an LCD. Then I’ll give you some example programs for programming it with either C or Python.

We have another tutorial on the DHT11 for the Arduino that goes into detail on relative humidity and how the DHT11 measures it. So instead of repeating all of that here, check out How to Set Up the DHT11 Humidity Sensor on an Arduino, then come back for the specifics on setting it up on the Raspberry Pi.

But just to quickly summarize… The DHT11 has a surface mounted NTC thermistor and a resistive humidity sensor. An IC on the back of the module converts the resistance measurements from the thermistor and humidity sensor into digital temperature (in °C) and relative humidity measurements.

There are two variants of the DHT11 you’re likely to come across. One is a three pin PCB mounted module and the other is a four pin stand-alone module. The pinout is different for each one, so connect the DHT11 according to which one you have:

I’ll explain how to use both C and Python to get temperature and humidity from the DHT11, so you’ll be able to incorporate the DHT11 into pretty much any existing RPi project.

We’ll be using WiringPi to program the DHT11 in C. If you don’t have WiringPi installed already, follow this link for instructions on how to install WiringPi.

For temperature in Celsius, un-comment line 72 where it says lcdPrintf(lcd, "Temp: %d.0 C", dht11_dat[2]);, then comment out line 73. To find out more about how to control text on an LCD with C, check out How to Setup an LCD on the Raspberry Pi and Program it With C.

We’ll be using the Adafruit DHT11 Python library. You can download the library using Git, so if you don’t have Git installed on your Pi already, enter this at the command prompt:

To output the DHT11 readings to an LCD, we’ll need to install another Python library called RPLCD to drive the LCD. To install the RPLCD library, we first need to install the Python Package Index, or PIP. PIP might already be installed on your Pi, but if not, enter this at the command prompt to install it:

That should about cover most of what you’ll need to get the DHT11 up and running on your Raspberry Pi. Hope this made it easier for you. Be sure to subscribe if you liked this article and found it useful, and if you have any questions or need help with anything, just leave a comment below…

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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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?

DHT11,temperature and humidity sensor is an advanced sensor unit that outputs a calibrated digital signal. It is highly reliable and stable over long term runs. It contains an 8 bit microprocessor and provides fast and high quality response.