why is my lcd screen not working arduino free sample
I am getting crazy on my first LCD example. I use an Arduino Uno and a brick chasis stacked onto it like in the 2nd picture on page 3 (the red one) of:
I did most of the examples for simple sensors and then tried the LCD example on page 16 (16 x 2 characters). I connected the 10 pin cable on BUS 2 of the brick chasis and on the LCD board, set the power switch to ON and backlight to OFF. The Uno board is connected via USB to my laptop.
Please post all of the code. Is this snippet in setup() or is it in loop(). If it is in loop() you are wasting our time - you must get the static display working first.
For each variation we need to see a copy of the actual code along with a picture of the result. The exact "weird" text is important, especially if it is the same each time.
I didn"t include the wires for the pot because that all works great. I figured you just wanted to see the data lines. I am wanting to try liquidcrystal1.0 however I attempted to try liquidcrystal440 couple days ago but stopped because when I copied the lib zip file over it wanted to write over my existing liquidchrystal, I assumed it would be named different but its not. So now after reading some I found I am suppose to rename my other liquidcrystal and then unzip the liquidcrystal1.0 . Is this right? seems silly I have to rename everything again if I use a different LCD, wonder why they cant come up with different names so they can all be in the same folder and then we can just #include the one we need for that project, like any other include file.
It is possible that you have a display with a controller that is out of spec (running slower than normal). Unfortunately there is nothing in LiquidCrystal.h that has anything to do with timing.
You could try using the LiquidCrystal1.0 library. This is the latest version of LiquidCrystal440 which was written for 40x4 displays but also works with the more common displays. I believe that it does a better job with "slow" LCD controllers. Start here: Google Code Archive - Long-term storage for Google Code Project Hosting..
Did you notice the difference in the appearance on my code versus the appearance of yours. After you paste in your code you should highlight it and use the "Code" button (which looks like a "#" symbol).
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Just connect the 100mm male-male jumper leads from breadboard to Uno GND, 5V, D2-D9. If you place the wires in straight lines it is easy to view on a photo.
The two controllers are in the attached photo are HC245, the seller sent me the sample code, but only this code works, I can do no other work, the following code that works:
There are various LCD displays out there, with little "I2C" boards on them to allow you to control the display with just 4 wires. I have had various problems with them and want to offer you some code.
I modified some existing code so that it talked to every possible I2C device, assumed it was an LCD display, and displayed its address on the LCD display, so you can see it! As a backup, in case the contrast is not set properly, it sends the I2C address down the serial port so you can see what it is. If you see an I2C address appearing on the Serial port, adjust your contrast on the back of the display.
This stems from the fact that the LCD controller itself does not inherently support the function and in fact treats the ASCII codes for and as displayable characters instead of control codes.
The fact that the LiquidCrystal library inherits from Print class and thus permits the use of println() essentially makes things worse. Instead of barfing and spitting out an error message it just happily displays two unrelated characters on the screen and the uninitiated have no idea of the cause.
In my opinion the basic LiquidCrystal library should concentrate on implementing all of the capabilities of the LCD controller and no more. If people want a library that more closely emulates a CRT (or LCD) terminal that is fine, but I think it should be done in a different library.
Yes, as I say, that error has been simply copied by one "tutorial" after another, and incorporated into the I²C backpacks since it "sort of" works so people think it is OK. But it makes contrast setting more difficult and wastes half a milliamp. That may not seem much to worry about except that the LCD itself uses less than a milliamp and this would be significant it operating from a battery. The backlight of course draws 20 mA.
Not really. You will note if you tried both ways, that the contrast control is much more flexible connected this way. Instead of working only over a very narrow range at one end, it works over a much wider range - at both ends.
This is the equivalent of turning the potentiometer all the way to the ground end. In general, it will work and is OK to test if you are having problems (as you are), but generally does not provide the clearest display.
And indeed, if that is the display with no code running, the fact that you get only half a line of blocks demonstrates that the display is definitely faulty.
So the verdict is a dead display. I was a bit puzzled with your original picture and thought you had a 2004 display but of course, it is a 1602. On a 2004, the uninitialised display is "blocks" on the first and third line.
Pardon us when we ask for your actual code, but we always want to check what is in your IDE, not what the tutorial said because - it isn"t always the same.
Not sure what you are trying to articulate there, but if you are talking about the resistor in series with pin 15, that is another story. It is unnecessary with AFAIK, all of the currently available 1602 and 2004 modules since "R8" on the back of the module is "101" or 100 Ohms.
Well, it always used to be, but on the one shown in #11, "R7" is now 330 Ohms so the external resistor is even less necessary. I can"t quite see what "R8" is doing here, but it appears to add another 220 Ohms also. An extra resistor will not hurt things, it will just dim the backlight slightly and save some current.
In this Arduino tutorial we will learn how to connect and use an LCD (Liquid Crystal Display)with Arduino. LCD displays like these are very popular and broadly used in many electronics projects because they are great for displaying simple information, like sensors data, while being very affordable.
You can watch the following video or read the written tutorial below. It includes everything you need to know about using an LCD character display with Arduino, such as, LCD pinout, wiring diagram and several example codes.
An LCD character display is a unique type of display that can only output individual ASCII characters with fixed size. Using these individual characters then we can form a text.
If we take a closer look at the display we can notice that there are small rectangular areas composed of 5×8 pixels grid. Each pixel can light up individually, and so we can generate characters within each grid.
The number of the rectangular areas define the size of the LCD. The most popular LCD is the 16×2 LCD, which has two rows with 16 rectangular areas or characters. Of course, there are other sizes like 16×1, 16×4, 20×4 and so on, but they all work on the same principle. Also, these LCDs can have different background and text color.
It has 16 pins and the first one from left to right is the Groundpin. The second pin is the VCCwhich we connect the 5 volts pin on the Arduino Board. Next is the Vo pin on which we can attach a potentiometer for controlling the contrast of the display.
Next, The RSpin or register select pin is used for selecting whether we will send commands or data to the LCD. For example if the RS pin is set on low state or zero volts, then we are sending commands to the LCD like: set the cursor to a specific location, clear the display, turn off the display and so on. And when RS pin is set on High state or 5 volts we are sending data or characters to the LCD.
Next comes the R/W pin which selects the mode whether we will read or write to the LCD. Here the write mode is obvious and it is used for writing or sending commands and data to the LCD. The read mode is used by the LCD itself when executing the program which we don’t have a need to discuss about it in this tutorial.
Next is the E pin which enables the writing to the registers, or the next 8 data pins from D0 to D7. So through this pins we are sending the 8 bits data when we are writing to the registers or for example if we want to see the latter uppercase A on the display we will send 0100 0001 to the registers according to the ASCII table. The last two pins A and K, or anode and cathode are for the LED back light.
After all we don’t have to worry much about how the LCD works, as the Liquid Crystal Library takes care for almost everything. From the Arduino’s official website you can find and see the functions of the library which enable easy use of the LCD. We can use the Library in 4 or 8 bit mode. In this tutorial we will use it in 4 bit mode, or we will just use 4 of the 8 data pins.
We will use just 6 digital input pins from the Arduino Board. The LCD’s registers from D4 to D7 will be connected to Arduino’s digital pins from 4 to 7. The Enable pin will be connected to pin number 2 and the RS pin will be connected to pin number 1. The R/W pin will be connected to Ground and theVo pin will be connected to the potentiometer middle pin.
We can adjust the contrast of the LCD by adjusting the voltage input at the Vo pin. We are using a potentiometer because in that way we can easily fine tune the contrast, by adjusting input voltage from 0 to 5V.
Yes, in case we don’t have a potentiometer, we can still adjust the LCD contrast by using a voltage divider made out of two resistors. Using the voltage divider we need to set the voltage value between 0 and 5V in order to get a good contrast on the display. I found that voltage of around 1V worked worked great for my LCD. I used 1K and 220 ohm resistor to get a good contrast.
There’s also another way of adjusting the LCD contrast, and that’s by supplying a PWM signal from the Arduino to the Vo pin of the LCD. We can connect the Vo pin to any Arduino PWM capable pin, and in the setup section, we can use the following line of code:
It will generate PWM signal at pin D11, with value of 100 out of 255, which translated into voltage from 0 to 5V, it will be around 2V input at the Vo LCD pin.
Here’s a simple code through which we can explain the working principle of the Liquid Crystal library. This is the code of the first example from the video:
First thing we need to do is it insert the Liquid Crystal Library. We can do that like this: Sketch > Include Library > Liquid Crystal. Then we have to create an LC object. The parameters of this object should be the numbers of the Digital Input pins of the Arduino Board respectively to the LCD’s pins as follow: (RS, Enable, D4, D5, D6, D7). In the setup we have to initialize the interface to the LCD and specify the dimensions of the display using the begin()function.
The cursor() function is used for displaying underscore cursor and the noCursor() function for turning off. Using the clear() function we can clear the LCD screen.
In case we have a text with length greater than 16 characters, we can scroll the text using the scrollDisplayLeft() orscrollDisplayRight() function from the LiquidCrystal library.
We can choose whether the text will scroll left or right, using the scrollDisplayLeft() orscrollDisplayRight() functions. With the delay() function we can set the scrolling speed.
The first parameter in this function is a number between 0 and 7, or we have to reserve one of the 8 supported custom characters. The second parameter is the name of the array of bytes.
So, we have covered pretty much everything we need to know about using an LCD with Arduino. These LCD Character displays are really handy for displaying information for many electronics project. In the examples above I used 16×2 LCD, but the same working principle applies for any other size of these character displays.
I hope you enjoyed this tutorial and learned something new. Feel free to ask any question in the comments section below and don’t forget to check out my full collection of 30+ Arduino Projects.
In this circuit, you’ll learn about how to use an LCD. An LCD, or liquid crystal display, is a simple screen that can display commands, bits of information, or readings from your sensor - all depending on how you program your board. In this circuit, you’ll learn the basics of incorporating an LCD into your project.
Open Up the Arduino IDE software on your computer. Coding in the Arduino language will control your circuit. Open the code for Circuit 15 by accessing the “SIK Guide Code” you downloaded and placed into your “Examples” folder earlier.
This bit of code tells your Arduino IDE to include the library for a simple LCD display. Without it, none of the commands will work, so make sure you include it!
This is the first time you’ll fire something up on your screen. You may need to adjust the contrast to make it visible. Twist the potentiometer until you can clearly see the text!
Initially, you should see the words “hello, world!” pop up on your LCD. Remember you can adjust the contrast using the potentiometer if you can’t make out the words clearly. If you have any issues, make sure your code is correct and double-check your connections.
Liquid Crystal displays or LCDs have been used in electronics equipment since the late 1970s. LCD displays have the advantage of consuming very little current And they are ideal for your Arduino projects.
In this article and in the accompanying video I’ll show you how easy it is to add an LCD display to your next Arduino design. I’ll also show you a very popular Arduino Shield that has a keypad which you can use in your projects as well.
Today LCD displays are used in a variety of items from test equipment to televisions. They’re inexpensive and versatile, this makes them ideal for all sorts of designs.
LCD displays do not emit light. Instead they block the passage of light, like little windows which open and shut the let light through. The liquid crystals used inside LCD displays are sandwiched between two layers of polarized material. By changing the orientation of the liquid crystals they allow light to pass or they block the light entirely.
Because transmissive LCD displays (the type we will be using) work by blocking light they require a backlight. Several methods have been used to create back lights including electroluminescent panels and fluorescent tubes. these days the most common form of backlight is an LED, in fact so-called LED televisions are usually just LCD screens with an LED backlight system.
Another type of LCD display, the passive-matrix display, does not require a backlight, it works using reflected light. This type of display is often found in digital watches.
The principles of liquid crystals were discovered in the late 1880s but work on Modern LCD displays did not begin until the mid-1960s. a number of patents were filed in the early 1970s and in 1973 the Sharp Corporation introduced LCD displays for calculators.
The first color LCD displays were developed in the early 1980s but production units were not commonly available until the mid-1990s. By the late 1990s LCD displays were quite common.
A number of LCD displays are available for experimenters. These low-cost monochrome displays are ideal for use with microcontrollers like the Arduino and micro computers like the Raspberry Pi.
These displays are available in a number of different configurations. The part number for the display generally relates to the number of rows and columns in the display.
Common display configurations include 16 x 2, 16 x 4 and 20 x 4. All of these displays are used in a virtually identical fashion the only difference being the number of columns and rows they have.
The LCD1602 display module is a very popular and inexpensive LCD display. It is available in a number of different colors such as blue yellow and green and can easily be connected to an Arduino or Raspberry Pi.
In operation data is sent down the parallel data lines for the display. There are two types of data that can be sent to the display. The first type of data are the ASCII characters which are to be displayed on the display. The other type of data are the control characters that are used to activate the various display functions.
Brightness– This is the input for the brightness control voltage, which varies between 0 and 5 volts to control the display brightness. On some modules this pin is labeled V0.
Because the LCD module uses a parallel data input it requires 8 connections to the host microcontroller for the data alone. Add that to the other control pins and it consumes a lot of connections. On an Arduino Uno half of the I/O pins would be taken up by the display, which can be problematic if you want to use the I/O pins for other input or output devices.
In 4-wire mode the data is sent a half a byte at a time, thus requiring only 4 data connections. The upper half of the data input (D4 to D7) is used while the other pins are not connected to anything.
We will begin our experiments by hooking up the LCD1602 to an Arduino Uno and running a few of the example sketches included with the Arduino IDE. This will allow you to get familiar with the display without needing to write any code.
We need to hookup our LCD display to our Arduino. The display can use any of the Arduino digital I/O pins as it has no special requirements, but if you hook it up as I’ve illustrated here you can run the example sketches without needing to make any modifications.
In addition to the LCD1602 display ands the Arduino Uno you will need a 10K trimpot ot potentiometer, this is used a s a brightness control for the display. You’ll also need a 220 ohm resistor to drop the voltage for the displays LED backlight.
The Arduino IDE includestheLiquidCrystallibraryand this library has a number of example sketches. I’ll go over three of them here but you can also try the other ones.
The sketch starts with a number of credits and a description of the required hardware hookup. You’ll note that this is the same hookup you just performed on your Arduino and LCD module.
We then initialize an object that we call “lcd” using the pinouts of the LCD display. If you decide to hook up your display to different pins then you’ll need to modify this section.
In the beginning of the loop we set our cursor to the first position in the second row. Note that the row numbers start with zero so the second row is row 1.
That ends the loop, so we start back at the top of the loop and repeat. The result will be a counter on the second line that counts seconds from the htime the Arduino was last reset.
Load the sketch up to your Arduino and observe your display. If you don’t see anything try adjusting the brightness control that you wired to the display.
The second example we will try isthe Scroll sketch. Scrolling is a useful technique when you can’t get your text to fit on one line of the LCD display.
In the loop the code demonstrates the use of thescrollDisplayLeftandscrollDisplayRightfunctions. As their names imply they move the text in a left or right direction.
Finally the last counter moves the text 16 positions to the left again, which will restore it back to the center of the display. The loop then repeats itself.
Custom characters are useful when you want to display a character that is not part of the standard 127-character ASCII character set. Thi scan be useful for creating custom displays for your project.
A character on the display is formed in a 5 x 8 matrix of blocks so you need to define your custom character within that matrix. To define the character you’ll use thecreateCharfunctionof the LiquidCrystal library. You are limited to defining a maximum of eight characters.
The Custom Character demonstration requires one additional component to be wired to the Arduino, a potentiometer (10K or greater) wired up to deliver a variable voltage to analog input pin A0.
As with the previous sketches we examined this one starts by loading theLiquidCrystallibrary and defining an object calledlcdwith the connection information for the display. It then moves on to define the custom characters.
Each character is defined as an array with 8 elements, the zeros and ones in the array indicate which elements in the character should be on and which ones should be off. Five arrays are defined, although the sketch actually only used four of them.
The last two arrays,amsUpandarmsDowndefine the shape of a little “stickman”, or “stickperson” if you want to be politically correct! This is done to show how we can animate a character on the display.
Finally the setup routine ends by printing a line to the first row of the LCD display. The line makes use of two of the custom characters, the “heart” and the “smiley”.
We begin by reading the value of the voltage on pin A0 using the ArduinoanalogReadfunction. As the Arduino has a 10-bit analog to digital converter this will result in a reading ranging from 0 to 1023.
We then use an Arduinomapfunction to convert this reading into a range from 200 to 1000. This value is then assigned to an integer calleddelayTime, which as its name implies represents a time delay period.
One thing you may have noticed about using the LCD display module with the Arduino is that it consumes a lot of connections. Even in 4-wire mode there are still a total of seven connections made to the Arduino digital I/O pins. As an Arduino Uno has only 14 digital I/O pins that’s half of them used up for the display.
In other cases you would need to resort to using some of the analog pins as digital pins or even moving up to an Arduino Mega which has many more I/O pins.
But there is another solution. Use the I2C bus adapter for the LCD display and connect using I2C. This only consumes two I/O pins and they aren’t even part of the set of digital I/O pins.
The I2C or IIC bus is theInter Integrated Circuitbus. It was developed by Philips Semiconductors in 1982 for use in the television industry. The idea was to allow the integrated circuits in televisions to “talk” to one another using a standard bus.
The bus has evolved to be used as an ideal method of communicating between microcontrollers, integrated circuits, sensors and micro computers. You can use it to allow multiple Arduinos to talk to each other, to interface numerous sensors and output devices or to facilitate communications between a Raspberry Pi and one or more Arduinos.
Power– This can be either 5 Volts or 3.3 volts, depending upon the application. Note that there are many precautions that must be observed if you are interfacing a 3.3 volt and 5 volt I2C device on the same bus.
In I2C communications there is the concept of Master and Slave devices. There can be multiples of each but there can only be one Master at any given moment. In most Arduino applications one Arduino is designated Master permanently while the other Arduinos and peripherals are the Slaves.
The Master transmits the clock signal which determines how fast the data on the bus is transferred. There are several clock speeds used with the I2C bus. The original design used 100 KHz and 400 KHz clocks. Faster rates of 3.4 MHz and higher are available on some I2C configurations.
The I2C Adapter for the LCD display is a tiny circuit board with 16 male header pins soldered to it. These pins are meant to be connected directly to the 16-pin connection on the LCD1602 display (or onto other displays that use the same connection scheme).
The device also has a 4-pin connector for connection to the I2C bus. In addition there is a small trimpot on the board, this is the LCD display brightness control.
Most of these devices have three jumpers or solder pads to set the I2C address. This may need to be changed if you are using multiple devices on the same I2C bus or if the device conflicts with another I2C device.
Most Arduino Unos also have some dedicated pins for I2C, these are internally connected to A4 and A5 and are usually located above the 14 digital I/O pins. Some models of the Uno have additional I2C connectors as well.
Note how much easier it is to use the I2C connection, which does not consume any of the Arduino Unos 14 digital I/O pins. Since A4 and A5 are being used for the I2C bus they can’t be used as analog inputs in this configuration.
Not all I2C adapters have the same I2C address, Most have address 0x20 but some use address 0x27 or 0x3F. You can change the address of your adapter by shorting some of the solder pads on the board.
If you don’t know the address you’ll need to find it out before you can run the sketches I’m about to show you. Fortunately there is a simple way of doing this, thanks to the great work of Nick Gammon.
Nick has written a simple I2C scanner sketch that he’s put into the public domain. It scans your I2C bus and gives you back the address of every I2C device it finds. I’ve repeated Nick’s sketch here, it’s also in the ZIP file that you can download with all of the code for this article.
Load this sketch into your Arduino then open your serial monitor. You’ll see the I2C address of your I2C LCD display adapter. You can then make note of this address and use it in the sketches we’ll be looking at now.
In order to run the subsequent sketches you’ll need to install another library. This is theNewLiquidCrystallibrarywhich, as its name implies, is an improved version of the LiquidCrystal library packaged with your Arduino IDE.
This library includes libraries for running the I2C adapter, which is why we are going to use it. But ist also can be used as a replacement for the original LiquidCrystal library and it offers improved performance over the original.
Remember that you’ll need to know the address of your I2C adapter before you run this sketch, so if you don’t know it go back and run Nick Gammon’s I2C Scanner first.
The sketch starts by loading the ArduinoWirelibrary. This is the Arduino library that facilitates communications over I2C and it’s part of your Arduino IDE installation.
On the next line we define the connections to the LCD display module from the I2C Adapter,. Note that these are NOT the connections from the Arduino, they are the connections used by the chip on the adapter itself.
In setup we set the size of the display and then print “Hello world!” on the first line in the first position. After a short delay we print “How are you?” on the second line.
Load the sketch and run it on your Arduino. If you can’t get it to work check out the address and connection information to be sure you have it right.
In this project we will put together a digital temperature and humidity gauge. It’s pretty accurate thanks to the use of a DHT22 temperature and humidity sensor. You could also substitute a cheaper DHT11 sensor but it won’t be as accurate.
We need to make a minor wiring adjustment to the hookup with our I2C adapter, specifically we will need to add a DHT22 temperature and humidity sensor into the circuit. The wiring is shown here:
As you can see the DHT22 is connected with its output tied to pin 7 of the Arduino. The other two connections are 5 volts and ground. Note that pin 3 of the DHT22 is not used.
This sketch also makes use of theDHTlibrary from Adafruit. We used this library in a previous article, “Using the HC-SR04 Ultrasonic Distance Sensor with Arduino” so you may want to take a look at that one in order to get it installed.
The key thing to note is that this library is dependant upon another Adafruit library, theirUnified Sensorlibrary. Both can be installed using the Library Manager in your Arduino IDE.
The sketch is similar to our demo sketch in that it creates an “lcd” object with the I2C and display connection information. It also defines a couple of parameters for the DHT22 sensor, as well as some floating variables to hold the temperature and humidity values.
Note that this displays the temperature in Celsius. If you want to change this to Fahrenheit its a simple matter of using some math. The formula( temp * 1.8 ) + 32will convert the results to Fahrenheit.
So far we have used the LCD1602 display module for all of our experiments. For our final demonstration we’ll switch to a popular Arduino shield that contains a LCD1602 along with some push buttons.
The LCD Keypad Shield is available from several different manufacturers. The device fits onto an Arduino Uno or an Arduino Mega and simplifies adding an LCD display to your project.
The Reset button is simply connected to the Arduino Reset pin and works just like the Reset button on the Arduino itself. This is common on many shields as the shields physically cover the Reset button.
The other five push buttons can really be used for anything you’d like to use them for. And the way they are hooked up is very interesting, at least it is to me!
Instead the buttons are connected to a resistor array that acts as a voltage divider. The entire array is connected to the Arduino’s analog A0 pin. One pin for five push buttons.
Pressing each button will send a voltage to the analog A0 pin. Because of the arrangement of the resistors each button will send a different voltage to the analog pin. By measuring the voltage level you can determine which button was pressed.
Note that the LCD is being used in 4-wire mode. The LCD itself is the same one used on the LCD1602 module, so all of the code for that module will work with the LCD Keypad Shield as well.
Now that you know how the LCD Keypad module works and which Arduino pins it uses all that remains is to install it onto your Arduino and load the demo sketch.
One thing – once the shield is installed on the Arduino you won’t have easy access to the unused I/O pins to connect any sensors or output devices you may want to use (although the demo sketch doesn’t need anything else connected). There are a couple of ways to get around this:
Use a shield that exposes the pins for prototyping before you install the LCD Keypad shield. In the video associated with this article I use a “Screw Shield” that brings all of the Arduino I/O pins out to a series of screw connectors. There are other similar shields. Using one of these shields is the easiest way to work with the LCD Keypad shield, as well as other Arduino shields.
The sketch begins by including theLiquidCrystallibrary. You can use the original one or the one includes with theNewLiquidCrystallibrary. We then set up an object with the LCD connections, note that these are just hard-coded as they won’t change.
Next we define a number of constants, one for each of the push buttons. Note that nothing is defined for the Reset button as it simply mimics the Arduino Reset button, however a constant is defined for the “none” condition.
We then define two variables. The first one holds the value of the selected pushbutton, the second holds the analog reading from port A0 where the push button input is detected.
After that we define a function calledread_LCD_buttons(). This function reads the value on analog port A0 and returns an integer corresponding to the button integers we defined earlier. Note that the function adds approximately 50 to each of the manufacturers specified values to account for intolerances in the resistors in the voltage divider.
We start the loop by placing the cursor 9 spaces over on the second line. We then use themillisfunction to display a counter that counts the time since the Arduino was reset. This is to test the Reset button.
We then call ourread_LCD_buttons()function and use it to display the value of the push button, right before the counter. Then we end the loop and do it again.
Load the code onto the Arduino and run it. You should see the value of each button as you press it, along with a counter that increments each second. If you press Reset the counter should reset itself back to zero.
As you can see LCD displays are pretty simple to use thanks to the availability of some excellent libraries for the Arduino. As these displays are also very inexpensive they will make an ideal addition to many of your Arduino projects.
And finally the LCD Keypad Shield is a convenient method of adding both a display and a simple keypad to your project, no wiring or soldering required.
This tutorial shows how to use the I2C LCD (Liquid Crystal Display) with the ESP32 using Arduino IDE. We’ll show you how to wire the display, install the library and try sample code to write text on the LCD: static text, and scroll long messages. You can also use this guide with the ESP8266.
Additionally, it comes with a built-in potentiometer you can use to adjust the contrast between the background and the characters on the LCD. On a “regular” LCD you need to add a potentiometer to the circuit to adjust the contrast.
Before displaying text on the LCD, you need to find the LCD I2C address. With the LCD properly wired to the ESP32, upload the following I2C Scanner sketch.
After uploading the code, open the Serial Monitor at a baud rate of 115200. Press the ESP32 EN button. The I2C address should be displayed in the Serial Monitor.
Displaying static text on the LCD is very simple. All you have to do is select where you want the characters to be displayed on the screen, and then send the message to the display.
In this simple sketch we show you the most useful and important functions from the LiquidCrystal_I2C library. So, let’s take a quick look at how the code works.
The next two lines set the number of columns and rows of your LCD display. If you’re using a display with another size, you should modify those variables.
Then, you need to set the display address, the number of columns and number of rows. You should use the display address you’ve found in the previous step.
To display a message on the screen, first you need to set the cursor to where you want your message to be written. The following line sets the cursor to the first column, first row.
Scrolling text on the LCD is specially useful when you want to display messages longer than 16 characters. The library comes with built-in functions that allows you to scroll text. However, many people experience problems with those functions because:
After reading the previous section, you should be familiar on how this sketch works, so we’ll just take a look at the newly created function: scrollText()
The messageToScroll variable is displayed in the second row (1 corresponds to the second row), with a delay time of 250 ms (the GIF image is speed up 1.5x).
In a 16×2 LCD there are 32 blocks where you can display characters. Each block is made out of 5×8 tiny pixels. You can display custom characters by defining the state of each tiny pixel. For that, you can create a byte variable to hold the state of each pixel.
Then, in the setup(), create a custom character using the createChar() function. This function accepts as arguments a location to allocate the char and the char variable as follows:
In summary, in this tutorial we’ve shown you how to use an I2C LCD display with the ESP32/ESP8266 with Arduino IDE: how to display static text, scrolling text and custom characters. This tutorial also works with the Arduino board, you just need to change the pin assignment to use the Arduino I2C pins.
We hope you’ve found this tutorial useful. If you like ESP32 and you want to learn more, we recommend enrolling in Learn ESP32 with Arduino IDE course.
In this tutorial, I’ll explain how to set up an LCD on an Arduino and show you all the different ways you can program it. I’ll show you how to print text, scroll text, make custom characters, blink text, and position text. They’re great for any project that outputs data, and they can make your project a lot more interesting and interactive.
The display I’m using is a 16×2 LCD display that I bought for about $5. You may be wondering why it’s called a 16×2 LCD. The part 16×2 means that the LCD has 2 lines, and can display 16 characters per line. Therefore, a 16×2 LCD screen can display up to 32 characters at once. It is possible to display more than 32 characters with scrolling though.
The code in this article is written for LCD’s that use the standard Hitachi HD44780 driver. If your LCD has 16 pins, then it probably has the Hitachi HD44780 driver. These displays can be wired in either 4 bit mode or 8 bit mode. Wiring the LCD in 4 bit mode is usually preferred since it uses four less wires than 8 bit mode. In practice, there isn’t a noticeable difference in performance between the two modes. In this tutorial, I’ll connect the LCD in 4 bit mode.
BONUS: I made a quick start guide for this tutorial that you can download and go back to later if you can’t set this up right now. It covers all of the steps, diagrams, and code you need to get started.
Here’s a diagram of the pins on the LCD I’m using. The connections from each pin to the Arduino will be the same, but your pins might be arranged differently on the LCD. Be sure to check the datasheet or look for labels on your particular LCD:
Also, you might need to solder a 16 pin header to your LCD before connecting it to a breadboard. Follow the diagram below to wire the LCD to your Arduino:
The resistor in the diagram above sets the backlight brightness. A typical value is 220 Ohms, but other values will work too. Smaller resistors will make the backlight brighter.
All of the code below uses the LiquidCrystal library that comes pre-installed with the Arduino IDE. A library is a set of functions that can be easily added to a program in an abbreviated format.
In order to use a library, it needs be included in the program. Line 1 in the code below does this with the command #include
Now we’re ready to get into the programming! I’ll go over more interesting things you can do in a moment, but for now lets just run a simple test program. This program will print “hello, world!” to the screen. Enter this code into the Arduino IDE and upload it to the board:
There are 19 different functions in the LiquidCrystal library available for us to use. These functions do things like change the position of the text, move text across the screen, or make the display turn on or off. What follows is a short description of each function, and how to use it in a program.
TheLiquidCrystal() function sets the pins the Arduino uses to connect to the LCD. You can use any of the Arduino’s digital pins to control the LCD. Just put the Arduino pin numbers inside the parentheses in this order:
This function sets the dimensions of the LCD. It needs to be placed before any other LiquidCrystal function in the void setup() section of the program. The number of rows and columns are specified as lcd.begin(columns, rows). For a 16×2 LCD, you would use lcd.begin(16, 2), and for a 20×4 LCD you would use lcd.begin(20, 4).
This function clears any text or data already displayed on the LCD. If you use lcd.clear() with lcd.print() and the delay() function in the void loop() section, you can make a simple blinking text program:
This function places the cursor in the upper left hand corner of the screen, and prints any subsequent text from that position. For example, this code replaces the first three letters of “hello world!” with X’s:
Similar, but more useful than lcd.home() is lcd.setCursor(). This function places the cursor (and any printed text) at any position on the screen. It can be used in the void setup() or void loop() section of your program.
The cursor position is defined with lcd.setCursor(column, row). The column and row coordinates start from zero (0-15 and 0-1 respectively). For example, using lcd.setCursor(2, 1) in the void setup() section of the “hello, world!” program above prints “hello, world!” to the lower line and shifts it to the right two spaces:
You can use this function to write different types of data to the LCD, for example the reading from a temperature sensor, or the coordinates from a GPS module. You can also use it to print custom characters that you create yourself (more on this below). Use lcd.write() in the void setup() or void loop() section of your program.
The function lcd.noCursor() turns the cursor off. lcd.cursor() and lcd.noCursor() can be used together in the void loop() section to make a blinking cursor similar to what you see in many text input fields:
Cursors can be placed anywhere on the screen with the lcd.setCursor() function. This code places a blinking cursor directly below the exclamation point in “hello, world!”:
This function creates a block style cursor that blinks on and off at approximately 500 milliseconds per cycle. Use it in the void loop() section. The function lcd.noBlink() disables the blinking block cursor.
This function turns on any text or cursors that have been printed to the LCD screen. The function lcd.noDisplay() turns off any text or cursors printed to the LCD, without clearing it from the LCD’s memory.
These two functions can be used together in the void loop() section to create a blinking text effect. This code will make the “hello, world!” text blink on and off:
This function takes anything printed to the LCD and moves it to the left. It should be used in the void loop() section with a delay command following it. The function will move the text 40 spaces to the left before it loops back to the first character. This code moves the “hello, world!” text to the left, at a rate of one second per character:
This function takes a string of text and scrolls it from right to left in increments of the character count of the string. For example, if you have a string of text that is 3 characters long, it will shift the text 3 spaces to the left with each step:
Like the lcd.scrollDisplay() functions, the text can be up to 40 characters in length before repeating. At first glance, this function seems less useful than the lcd.scrollDisplay() functions, but it can be very useful for creating animations with custom characters.
lcd.noAutoscroll() turns the lcd.autoscroll() function off. Use this function before or after lcd.autoscroll() in the void loop() section to create sequences of scrolling text or animations.
This function sets the direction that text is printed to the screen. The default mode is from left to right using the command lcd.leftToRight(), but you may find some cases where it’s useful to output text in the reverse direction:
This code prints the “hello, world!” text as “!dlrow ,olleh”. Unless you specify the placement of the cursor with lcd.setCursor(), the text will print from the (0, 1) position and only the first character of the string will be visible.
This command allows you to create your own custom characters. Each character of a 16×2 LCD has a 5 pixel width and an 8 pixel height. Up to 8 different custom characters can be defined in a single program. To design your own characters, you’ll need to make a binary matrix of your custom character from an LCD character generator or map it yourself. This code creates a degree symbol (°):
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The Arduino family of devices is features rich and offers many capabilities. The ability to interface to external devices readily is very enticing, although the Arduino has a limited number of input/output options. Adding an external display would typically require several of the limited I/O pins. Using an I2C interface, only two connections for an LCD character display are possible with stunning professional results. We offer both a 4 x 20 LCD.
The character LCD is ideal for displaying text and numbers and special characters. LCDs incorporate a small add-on circuit (backpack) mounted on the back of the LCD module. The module features a controller chip handling I2C communications and an adjustable potentiometer for changing the intensity of the LED backlight. An I2C LCD advantage is that wiring is straightforward, requiring only two data pins to control the LCD.
A standard LCD requires over ten connections, which can be a problem if your Arduino does not have many GPIO pins available. If you happen to have an LCD without an I2C interface incorporated into the design, these can be easily
The LCD displays each character through a matrix grid of 5×8 pixels. These pixels can display standard text, numbers, or special characters and can also be programmed to display custom characters easily.
Connecting the Arduino UNO to the I2C interface of the LCD requires only four connections. The connections include two for power and two for data. The chart below shows the connections needed.
The I2C LCD interface is compatible across much of the Arduino family. The pin functions remain the same, but the labeling of those pins might be different.
Located on the back of the LCD screen is the I2C interface board, and on the interface is an adjustable potentiometer. This adjustment is made with a small screwdriver. You will adjust the potentiometer until a series of rectangles appear – this will allow you to see your programming results.
The Arduino module and editor do not know how to communicate with the I2C interface on the LCD. The parameter to enable the Arduino to send commands to the LCD are in separately downloaded LiquidCrystal_I2C library.
The LiquidCrystal_I2C is available from GitHub. When visiting the GitHub page, select the Code button and from the drop-down menu, choose Download ZIP option to save the file to a convenient location on your workstation.
Before installing LiquidCrystal_I2C, remove any other libraries that may reside in the Arduino IDE with the same LiquidCrystal_I2C name. Doing this will ensure that only the known good library is in use. LiquidCrystal_I2C works in combination with the preinstalled Wire.h library in the Arduino editor.
To install the LiquidCrystal_I2C library, use the SketchSketch > Include Library > Add .ZIP Library…from the Arduino IDE (see example). Point to the LiquidCrystal_I2C-master.zip which you previously downloaded and the Library will be installed and set up for use.
Several examples and code are included in the Library installation, which can provide some reference and programming examples. You can use these example sketches as a basis for developing your own code for the LCD display module.
There may be situations where you should uninstall the Arduino IDE. The reason for this could be due to Library conflicts or other configuration issues. There are a few simple steps to uninstalling the IDE.
The I2c address can be changed by shorting the address solder pads on the I2C module. You will need to know the actual address of the LCD before you can start using it.
Once you have the LCD connected and have determined the I2C address, you can proceed to write code to display on the screen. The code segment below is a complete sketch ready for downloading to your Arduino.
The code assumes the I2C address of the LCD screen is at 0x27 and can be adjusted on the LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27,16,2); as required.
Similar to the cursor() function, this will create a block-style cursor. Displayed at the position of the next character to be printed and displays as a blinking rectangle.
This function turns off any characters displayed to the LCD. The text will not be cleared from the LCD memory; rather, it is turned off. The LCD will show the screen again when display() is executed.
After 40 spaces, the function will loop back to the first character. With this function in the loop part of your sketch, you can build a scrolling text function.
Scrolling text if you want to print more than 16 or 20 characters in one line then the scrolling text function is convenient. First, the substring with the maximum of characters per line is printed, moving the start column from right to left on the LCD screen. Then the first character is dropped, and the next character is displayed to the substring. This process repeats until the full string has been displayed on the screen.
The LCD driver backpack has an exciting additional feature allowing you to create custom characters (glyph) for use on the screen. Your custom characters work with both the 16×2 and 20×4 LCD units.
A custom character allows you to display any pattern of dots on a 5×8 matrix which makes up each character. You have full control of the design to be displayed.
To aid in creating your custom characters, there are a number of useful tools available on Internet. Here is a LCD Custom Character Generator which we have used.
This article gives you a step-by-step guide to becoming a pro in using Liquid Crystal Display. We will use a free Arduino Simulator to try all the examples without leaving your PC. No hardware is needed.
You can see that the first eight characters are user-defined. It allows you to create custom shapes and store them. You will see how to create custom characters and load them in your following Arduino projects. Let us start with a basic example.
We will print a simple text on the LCD using Arduino UNO in this example. In this case, you control what is displayed on the Arduino readily. You only need four cables. Power, Ground, I2C data, and I2C clock.
Use the link above to run the code. You can tinker with the code to change the text displayed or the position. The best thing about the link is that it will save the project as your version. It will be automatically saved under my projects tab on the wokwi site if you are logged in.
The below line code adds the LCD library to your project. This consists of all the LCD-related functions. Since we are using the I2C version, we have included the standard LCD library made for the I2C version.#include
The following line of the code resets and initializes all the LCD registers and prepares them for project usage. This function will be called only once in thesetup()function.lcd.init();
To turn on the backlight, you can use the below code. You will be able to see the contents of the display without a backlight, too, if it is a green LCD. Backlight, nevertheless, makes the project more beautiful and reading crisper.lcd.backlight();
You can mention where the characters should be displayed. You can always use the below function to set/reset the cursor position. This function will be beneficial when you have to display time or a counter that demands the cursor to always be in the same position.
The first parameter tells the position column-wise (0indicated first place,1indicates the second place, and so on). The second parameter tells the row number. We have only two rows (0and1).lcd.setCursor(1, 0);
This completes a basic introduction to the LCD as well as an example project to start the LCD exploration. In the coming sections, we will see different projects as soon as possible
Ms.Josey 
Ms.Josey