lcd displays with arduino quotation

This tutorial includes everything you need to know about controlling a character LCD with Arduino. I have included a wiring diagram and many example codes. These displays are great for displaying sensor data or text and they are also fairly cheap.

The first part of this article covers the basics of displaying text and numbers. In the second half, I will go into more detail on how to display custom characters and how you can use the other functions of the LiquidCrystal Arduino library.

As you will see, you need quite a lot of connections to control these displays. I therefore like to use them with an I2C interface module mounted on the back. With this I2C module, you only need two connections to control the LCD. Check out the tutorial below if you want to use an I2C module as well:

These LCDs are available in many different sizes (16×2 1602, 20×4 2004, 16×1 etc.), but they all use the same HD44780 parallel interface LCD controller chip from Hitachi. This means you can easily swap them. You will only need to change the size specifications in your Arduino code.

For more information, you can check out the datasheets below. The 16×2 and 20×4 datasheets include the dimensions of the LCD and in the HD44780 datasheet you can find more information about the Hitachi LCD driver.

Most LCDs have a built-in series resistor for the LED backlight. You should find it on the back of the LCD connected to pin 15 (Anode). If your display doesn’t include a resistor, you will need to add one between 5 V and pin 15. It should be safe to use a 220Ω resistor, but this value might make your display a bit dim. You can check the datasheet for the maximum current rating of the backlight and use this to select an appropriate resistor value.

After you have wired up the LCD, you will need to adjust the contrast of the display. This is done by turning the 10 kΩ potentiometer clockwise or counterclockwise.

Plug in the USB connector of the Arduino to power the LCD. You should see the backlight light up. Now rotate the potentiometer until one (16×2 LCD) or 2 rows (20×4 LCD) of rectangles appear.

In order to control the LCD and display characters, you will need to add a few extra connections. Check the wiring diagram below and the pinout table from the introduction of this article.

We will be using the LCD in 4-bit mode, this means you don’t need to connect anything to D0-D3. The R/W pin is connected to ground, this will pull the pin LOW and set the LCD to WRITE mode.

To control the LCD we will be using the LiquidCrystal library. This library should come pre-installed with the Arduino IDE. You can find it by going to Sketch > Include Library > LiquidCrystal.

The example code below shows you how to display a message on the LCD. Next, I will show you how the code works and how you can use the other functions of the LiquidCrystal library.

After including the library, the next step is to create a new instance of the LiquidCrystal class. The is done with the function LiquidCrystal(rs, enable, d4, d5, d6, d7). As parameters we use the Arduino pins to which we connected the display. Note that we have called the display ‘lcd’. You can give it a different name if you want like ‘menu_display’. You will need to change ‘lcd’ to the new name in the rest of the sketch.

In the loop() the cursor is set to the third column and first row of the LCD with lcd.setCursor(2,0). Note that counting starts at 0, and the first argument specifies the column. If you do not specify the cursor position, the text will be printed at the default home position (0,0) if the display is empty, or behind the last printed character.

Next, the string ‘Hello World!’ is printed with lcd.print("Hello World!"). Note that you need to place quotation marks (” “) around the text. When you want to print numbers or variables, no quotation marks are necessary.

The LiquidCrystal Arduino library has many other built-in functions which you might find useful. You can find an overview of them below with explanation and some code snippets.

Clears the LCD screen and positions the cursor in the upper-left corner (first row and first column) of the display. You can use this function to display different words in a loop.

This function turns off any text or cursors printed to the LCD. The text/data is not cleared from the LCD memory. This means it will be shown again when the function display() is called.

Scrolls the contents of the display (text and cursor) one space to the left. You can use this function in the loop section of the code in combination with delay(500), to create a scrolling text animation.

This function turns on automatic scrolling of the LCD. This causes each character output to the display to push previous characters over by one space. If the current text direction is left-to-right (the default), the display scrolls to the left; if the current direction is right-to-left, the display scrolls to the right. This has the effect of outputting each new character to the same location on the LCD.

The following example sketch enables automatic scrolling and prints the character 0 to 9 at the position (16,0) of the LCD. Change this to (20,0) for a 20×4 LCD.

With the function createChar() it is possible to create and display custom characters on the LCD. This is especially useful if you want to display a character that is not part of the standard ASCII character set.

Technical info: LCDs that are based on the Hitachi HD44780 LCD controller have two types of memories: CGROM and CGRAM (Character Generator ROM and RAM). CGROM generates all the 5 x 8 dot character patterns from the standard 8-bit character codes. CGRAM can generate user-defined character patterns.

/* Example sketch to create and display custom characters on character LCD with Arduino and LiquidCrystal library. For more info see www.www.makerguides.com */

After including the library and creating the LCD object, the custom character arrays are defined. Each array consists of 8 bytes, 1 byte for each row. In this example 8 custom characters are created.

In this article I have shown you how to use an alphanumeric LCD with Arduino. I hope you found it useful and informative. If you did, please share it with a friend that also likes electronics and making things!

I would love to know what projects you plan on building (or have already built) with these LCDs. If you have any questions, suggestions, or if you think that things are missing in this tutorial, please leave a comment down below.

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.

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:

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 . When you include a library in a program, all of the code in the library gets uploaded to the Arduino along with the code for your program.

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:

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.

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 (°):

If you found this article useful, subscribe via email to get notified when we publish of new posts! And as always, if you are having trouble with anything, just leave a comment and I’ll try to help you out.

We have published quite a number of tutorials using different displays with the Arduino, with the most recent being the tutorial on displaying graphics on all kind of displays with Arduino. For today’s tutorial, we will look into achieving more with displays by implementing a menu based system with the Nokia 5110 LCD display and the Arduino. The menu is one of the easiest and most intuitive ways through which users interact with products that require navigation. From mobile phone to PCs, its applications are endless. Today we will explore how to add this cool feature to your Arduino project.

At the heart of today’s project is the Nokia 5110 LCD Display. The Nokia 5110 LCD is one of the most popular LCD display among makers. It was originally developed for use as a screen for cell phones and was used in lots of mobile phones during the 90’s. The display uses a low power CMOS LCD controller/driver, the PCD8544, which drives the 84×48px graphics display. In a normal state, the display consumes about 6 to 7mA which makes it quite ideal for low power devices. We have published quite a number of tutorials on this display that might help you understand how to drive such a display.

To showcase how to create the menu on a display with the Arduino, we will build a simple demo menu with three pages.  To navigate through the menu, we will use 3x push buttons. The first to scroll up, the second to scroll down and the third one to select a highlighted option. The first screen/page of the menu will serve as the home page and will host the options that open the next two screens/pages. The second page will open after the first menu option on the homepage has been selected. Users will be able to change the contrast of the display using the up and down push buttons to increase or reduce it respectively. By pressing the select button, users will be able to go back to the home page. The second option on the homepage displays the third page, where users will be able to turn the backlight of the display on/off by pressing the select item button.

To make the schematics easy to follow, a pin map of the connection between the Arduino Uno and the Nokia 5110, which isthe major component, is shown below.

Looking at the schematics, you will see that the push buttons are connected to the Arduino without the common pull-up or pull-down resistors. This is because we will use the Arduino’s internal pull-up resistor. You can read more about using pull-up/down resistors here. If you have any challenges understanding the concept, do reach out to me via the comment section.

To be fair, the code for today’s tutorial is a little bit complex and while I will do my best to break it down and ensure you understand the basics, it might take you building your own menu to fully grab the concept. The code for today is heavily dependent on two major libraries; The Adafruit GFX library and the Adafruit Nokia 5110 LCD Library. The Adafruit GFX library is probably one of the libraries we use the most in our tutorials. It makes it easy to display graphics and perform simple animations on supported displays. The Nokia 5110 LCD library, on the other hand, reduces the amount of work and code required to interact with the LCD.

We start the code as with other sketches by including all the libraries required for the project which in this case, are the Adafruit GFX and Nokia 5110 LCD libraries.

Next, we write the void setup function. Here we declare all the pins to which the push buttons are connected as inputs and set digital pin 7 as output since the Light pin of the LCD is connected to it. This pin will be used to turn the backlight on/off later on.

Go through the schematics one more time to ensure everything is connected as it should be, then connect the Arduino to your computer and upload the code. After a couple of seconds, you should see the menu displayed on the LCD and it should respond to the push buttons when pressed.

In the previous tutorial I showed how to build a weather station using DHT11 and BMP180 with an Arduino. However, the project has a downside which is the power consumption of the 16X2 LCD. If we were building a battery powered project with the desire to last for several weeks and probably several months, like a weather station for instance, then we’ll have to replace the LCD keypad shield from the previous tutorials and go for something like the low powered Nokia 5110 84×84 LCD display. In this tutorial I will be showing you how to drive this display with the Arduino and thus build projects with longer battery life.

Since we are just going to drive the display we won’t be needing sensors for this tutorial, however we will need the components listed below which include the Nokia 5110 itself and we will show how to drive the display using an Arduino board.

The Nokia 5110 display is basically a graphic LCD display useful for a lot of applications. It was intended originally to be used as a screen for cell phones and was used in lots of mobile phones during the 90’s. This display uses a low powered CMOS LCD controller/driver PCD8544, which drives the graphic display of size 84×48. It is very cheap and costs about 3$. You can get one here.

The Nokia 5110 LCD can display text, graphics as well as bitmaps. When this display is fully lit, it draws about 10mA but with the backlight off, it draws as low as 0.4mA. The power consumed by this display is very low compared to that of the keypad LCD shield used in the previous tutorial. I will be using the Arduino Mega for this tutorial as usual and you can buy one here. You can also buy jumpers, breadboards and power bank which you will be needing for this tutorial.

Before we start writing the code for this project, first we need to download the 5110 LCD graph library that was made by rinky-dink electronics. The library does most of the heavy lifting and makes it easy for us o use the LCD. Click here to visit the download page and then download the LCD5110_graph zip file. When done, unzip the file to your preferred location and then rename the unzipped folder to something simple like “LCD5110”. Copy and paste this folder in your arduino library folder, then run your arduino IDE.

Click on the file, then on examples and then click on LCD5110. Since we are using the Arduino Mega, under the LCD5110 drop down click on Arduino (AVR) and the open up the LCD graph demo file.

In the code we only have to change a few things. we can see from the comment section above that the RST pin of the display was connected to pin 11 but in our case we connected this pin to pin 12 of the Arduino Mega. We also have to change the CS from pin 12 to 11.

The first line after the comment section, the LCD5110 library was included and after that a myGLCD object was created with the numbers being the pins to which the LCD is connected. The last two values in the myGLCD object is the RST and CS values which has been changed as explained initially.

with this done, we move to the setup function. In the setup function, the InitLCD method is used to initialize the display and this method takes in a parameter for the display contrast. The contrast value is between 0-127 and since we didn’t pass in any value the default value which is 70 will be used. Next, the setFont method is called which sets smallFont as the display font style is called and lastly, the randomSeed function which is used to initialize the random number generator using analogRead on an unconnected pin as a random input.

In the loop function, on the first line the screen buffer is cleared using the clrScr method. The drawBitmap method was used to draw the arduino logo and this logo is placed in the screen buffer when the method is called. The update method is used to copy the screen buffer to the screen then we give it a delay of 2 seconds before clearing the screen buffer again.

Most of the functions used in the project have names that are self-explanatory like myGLCD.drawLine needs no explanation for instance as its clear the function draws a line.

Here is the full code for this project. Its an example from the Library named LCD5110_Graph_Demo and how to get to it has been described at the beginning of this section.

Are you bored by making those projects that don’t grab your interest? And, that’s why feeling demotivated? And are you looking for some interesting project that excites and motivates you? You’re in the right spot. Because, In this tutorial, we’ll interface “Nokia 5110 LCD with Arduino UNO” The Nokia 5110 LCD is one of the devices that are used to display words, numbers, images, etc. The reason to use Nokia LCD is that it’s inexpensive and easily get interfaced with Arduino.

Nokia 5110 is a simple graphic LCD. Initially, it was made to use as a mobile phone screen. The LCD contains the PCD8544 controller in it. Practically, it’s a low-powered controller. This controller was designed to display 48 rows and 84 cols on an LCD screen. The LCD is easy to solder and mount on board. Also, it’s easy to interface with any microcontroller.

Assemble the circuit to interface “Nokia 5110 LCD with Arduino UNO” according to the above-given diagram. Upload the code in Arduino. When you upload the code in it, the Arduino transfers it to the LCD through wires/buses. And, you will see that LCD will display “Hello World”. Use the potentiometer to increase or decrease the light intensity.

In the void setup, initialize the LCD by Lcd.begin(84, 48). Remember, that this 84 and 48 is the dimension of LCD. Then createchar( ) is used to create the character fonts for the LED matrices.

Here I’ve added a the 5110 LCD to a logger recording data from a BME280 & Tipping Bucket Rain gauge. If the BME  survives in our field environment, this will become a standard configuration for our climate stations. I

For our first project, we’re using both the inbuilt LCD screen and WiFi module to get text data of famous quotes. Since we’re all nerds at DIYODE, we’ve of course chosen to choose famous programming quotes. The center button of the Wio Terminal will be used to load a new quote and display it on the screen.

WiFi is involved here because we’re using a simple Web API to gather data and display it live. Since it’s connecting to WiFi, we could connect it with virtually any other web interface and make it work.

After installing the required WiFi libraries, we can open a new Arduino sketch and pop in the following initialization code. Unless your WiFi network so happens to be named “YOUR_WIFI_NAME” and has the password “YOUR_WIFI_PASSWORD”, you’ll want to change them to your home network details!

There isn’t a ton of libraries we need to import here. We’re using the Arduino JSON, rpcWiFi and HTTPClient libraries to handle the internet connection and data, and the TFT_eSPI library to handle the screen on the Wio Terminal.

Finally, we can actually draw the quote text on the Wio Terminal’s screen! This isn’t that tricky, except for that weird for loop with the numbers in it. The purpose of this is to provide some basic text wrapping.

Text wrapping is the process of bringing text fields down to the next line on the screen if it’s too long – which is often the case with quotes. The LCD library does have this function built-in, but it wasn’t cooperating for us, so we wrote it ourselves!

Essentially, we’re taking ‘chunks’ out of the text with the substring function and writing each to one line of the Wio Terminal’s LCD screen. The ‘len’ variable describes the number of characters on each line. If the function is confusing, just change some values and observe the effects!

…and boom! It’s all working. Inspiring programming quotes at the press of a button. Obviously, this isn’t the most practical program ever – but it’s a good starting program to experiment with the Wio Terminal and to demonstrate its capabilities with precisely zero external wiring required.

The Snake Eyes Bonnet is a Raspberry Pi accessory for driving two 128x128 pixel OLED or TFT LCD displays, and also provides four analog inputs for sensors. It"s perfect for maki…

Initialize with a string constant in quotation marks; the compiler will size the array to fit the string constant and a terminating null character, Str4

Generally, strings are terminated with a null character (ASCII code 0). This allows functions (like Serial.print()) to tell where the end of a string is. Otherwise, they would continue reading subsequent bytes of memory that aren"t actually part of the string.

This means that your string needs to have space for one more character than the text you want it to contain. That is why Str2 and Str5 need to be eight characters, even though "arduino" is only seven - the last position is automatically filled with a null character. Str4 will be automatically sized to eight characters, one for the extra null. In Str3, we"ve explicitly included the null character (written "\0") ourselves.

Note that it"s possible to have a string without a final null character (e.g. if you had specified the length of Str2 as seven instead of eight). This will break most functions that use strings, so you shouldn"t do it intentionally. If you notice something behaving strangely (operating on characters not in the string), however, this could be the problem.

It is often convenient, when working with large amounts of text, such as a project with an LCD display, to setup an array of strings. Because strings themselves are arrays, this is in actually an example of a two-dimensional array.

Granted, the Arduino doesn’t have much use for text when used on it’s own. It has no display. But a display can be attached, or text can be send/received through the serial port and other ways of communication.

In the case of a string, the array keeps going, until your Arduino finds a NULL character. The NULL character terminates the string – or indicates the end of the string.

It’s character zero. But we do not (yet) have to worry about that – but it is something to keep in mind. Since strings are quite often used, the language “C” which we use for Arduino Programming, comes with a standard library of string related functions, which handle quite a lot already automatically.

Note that if the number is bigger than the number of characters we need, then this will work just fine. However, your Arduino might allocate the extra characters as well and waste memory space as we’re not using it. On the other hand, if you expect the string to change in the program and all those characters might be needed, then you’d already be prepared.

Not really. Remember how I said before that the variable (in our example “Name”) actually points to the memory location of the first element in the array? It’s a memory address, which is not the same as a string. Believe me, this is something you’ll run into quite often, and it’s one of the reason why I’m not a fan of the C-language (I’m more of a Pascal fan – and plenty of people will argue with me on that one).

The code highlighting of the Arduino IDE text editor, will show you if a string “breaks” or not, by changing character colors in the string you just typed.

The third line shows us the trick with the backslash. We placed them right before the special character, so the compiler knows that the next character is special and part of the string.

Note that when you want the next character to be special as well, then you’d need to “escape” those as well. For example if we add multiple double quotes around the word “guest”: Serial.println("Hello \"\"guest\"\", welcome to Arduino");

However, if our string becomes shorter, for example by replacing “Hans” with “Max” (my other nephew), then we would need to add the NULL character again:

Obviously, using ASCII is not the obvious way to do it when you’d like to assign text to a string. However, there are scenario’s where this can be very practical. I’ll illustrate this with a quick nonesense example, which quickly lists all the letters of the alphabet, where we can use a “for” loop to count from 65 (=A) to 90 (=Z).

The “for” loop can be used with numbers, or basically anything we can enumerate, or in other words: Data types that we can count with fixed increments, or whole numbers. For example, a byte, or an integer (both whole numbers):

“sizeof()” does the same thing as “strlen()”, however it will include the NULL character in it’s count. It actually returns the size of the full array, even if it would be filled with NULL characters.

When we added ” has two nephews, called Bram and Max!” to that string/array, we royally exceed the pre-defined space, and your Arduino will try to print that anyway. Not being able to find the NULL character (we have overwritten it with a non-NULL character, a space-character, in this example), it will keep spitting out whatever is in memory until it finds a NULL character. Which might be right away, or never …

The tedious and cumbersome things we had to do with the old “string” (lowercase: Array of Char), are done much easier with the “String” (Capital “S”: an object) object … but what is an object?

Another reason is that once an object has been defined, it actually kind-a behaves like a data type, which can use for variables. Say we have one “car” then we create a variable “MyCar” as the object (data type) “car”. But if we have a garage filled with cars, then we can re-use that same definition to create multiple variables (MyCar, YourCar, DadsCar, MomsCar), or even an array of cars (Cars[0], Cars[1], Cars[2],…).

With “Serial” we have already seen the methods (functions) “begin”, “print” and “println”. We call these methods to have the object do something , like start communication, or send a string to our Serial Monitor of our Arduino IDE.

Maybe you’ve now seen that we always call an object in a format like this: OBJECT.METHOD or OBJECT.PROPERTY? We call the object and separate object and method (or property) with a period.

As mentioned and shown before: the array of char variant of a string is a little cumbersome to work with. So the good people at Arduino created an object to make working with strings easier. Again a reminder: it’s the “String” with a capital “S”!!!

As we have seen with the old “string”, we can simply create a variable and assign it a value in one single line. Nothing new there, well except for the keyword “String” of course and the lack of square brackets.

You see? We can assign a much larger string than what we started out with, and when printing it, we experience zero problems. This is already a second point where the object is easier to use.

Now the “String” object, has a lot of methods (functions) we can work with, which can make our life a lot easier when working with strings, and this is where we will really see the power of objects.

We create the String object “Name” and assign it the value “Hans” (lines 7 and 8), which we can print with “Serial” as we have seen before. Now in line 12, we retrieve the length of our string – which is just the number of characters in the string, and not including the NULL terminating character. This is done with the “length()” method of the “String” object: Name.length() . This method will return a number, an integer, which we send right away to “Serial.print”.

The “String” object however is even more powerful and can right away convert a number (int in this example) to a string, and replace or attach it to an existing string – see line 34 – which is something we cannot do with the previous “string” array of characters.

Now if we know that String("some text") returns a “String” object, and we know that we can glue strings together with the plus symbol (+), and we know that “Serial.println()” take a “String” as a parameter,… then we can do some tricks to save us the hassle of writing 2 “Serial” lines (print() and println()) whenever we want to print values or variables.

The reason why this fails, is because we are comparing a string with the memory location “pointer” of an array. Which will not be the same obviuosly. We actually need to use a special function for this: “strcmp()”  (read that as “string compare”)

What is the purpose of declaring LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE); if we are using pins A4 and A5? I know that 0x27 is the ic address but what is the rest for?

I am getting a error while i m going to add zip file of lcd library error id this zip file does not contains a valid library please help me to resolve this issue as soon as possible.....

Hey guys. My LCD works fine using the above instructions (when replacing the existing LCD library in the Arduino directory) but I can"t get the backlight to ever switch off. Suggestions?

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.

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.

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.

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.