how to program lcd display quotation

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 . 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:

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:

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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About: I"ve been a president at two colleges and currently provide consulting services for small businesses, non-profits, and educational organizations. In a previous life, I was a human factors engineer and human pe…

If you like collecting quotations like I do, then this instructable is for you. This instructable will show you how to put together a way to display your quotes for all to see, using things you probably already have around the house.

Any kind of quote will do, but because the picture frame scrolls through the images that will contain the quotes it works best if you keep the quotes short. Longer quotes, although interesting, may not remain on screen long enough to be read. If you have a number of longer quotations, see "Some Final Notes" at the end of this instructable for tips that you can consider for longer display times.

Look at the sample images stored on your LCD picture frame. For my frame, all of the sample images were 856x480 pixels. To determine this, right click on the image file, and select Properties. You should see a number of tabs, one of which should be called “Details.” Click on the details tab; under Image you should see a width and height. Write this down or keep the window open, because we will use it to set up PowerPoint.

Take the smaller of the two numbers (usually the height), and divide that by the larger number. In my case, 480/856=0.5607. Checking the table below (which shows common screen image ratios), I can see that the native images on my LCD picture frame are just about in 16:9 format.

Open PowerPoint, and start a new presentation. On the ribbon, click Design, Page Setup. In the setup dialog box, select the image format that matches the native format of your LCD picture frame. We do this because it helps prevent the software driving the frame from cropping or stretching the images unnecessarily. Click Home on the ribbon.

Now, look for the New Slide button. In the lower-right corner of the button, there should be a small arrow. Click on the arrow, which should bring up a bunch of options for slide layouts. Select the Blank Slide.

At this point, your presentation should have two slides: The initial default title slide, and your newly inserted blank slide. Click on the first slide (the title slide), click your right mouse button, and select delete. You should be left with a single blank slide in your presentation, sized to the native image size of your LCD picture frame.

In many cases, the picture won’t fill the slide because it’s in a different format than the native format for the LCD picture frame. Thus, we’ll need to resize the image to fit. At the same time, we don’t want to distort the image either. Here’s the most straightforward approach:

Move the image all the way to the right edge of the PowerPoint slide, then up until the top of the image aligns with the top of the slide. The image should “snap” to the edges of the slide.

Grab the lower-left corner of the image and drag it to the left-center edge of the slide. By grabbing the lower-left corner (or any corner, for that matter), you maintain the aspect ratio of the image and you can resize it without distortion. Again, the image should snap to the edge of the slide.

With the picture still selected, click on the “Crop” button. The circle-shaped resize handles at the image’s corners should change to crop handles. Grab the bottom-center crop handle with your mouse, and push up until it snaps onto the bottom of the slide.

A word about cropping the images: When you crop images, you may lose parts of the image that make it a pleasing composition. Feel free to drag any of the crop handles and move the photo around until you get the image looking the way you want. Just make sure when you’re finished, the image is aligned with the edges of the PowerPoint slide.

Select the image, and click the Format button under Picture Tools on the ribbon. Select the “Compress Pictures” button. In the Compress Pictures dialog, choose “Options.” Set up the Compression Options like the image below and click OK. You’ll only have to make these settings the first time. Finally, click OK on the Compress Pictures dialog. This makes the image smaller, and removes the cropped portions of the picture, leaving a slide-filling image.

Click Insert on the ribbon, and click on the text box button. Select a font, font color, and size that make the quote readable. Move to your word processing file with your quotes, highlight and copy the quotation you want to use, and then use "Paste Special, Unformatted Text" to paste the quotation into the text box.

Resize the text box as necessary, and place it in a good location on the image. For the quote here I used 24-point Arial Black in white (I have seen the quote attributed to Will Rodgers, Fred Rogers, and Wynn Catlin; I think Will is most likely but I’m amused by the incongruity of attributing it to Mr. Rogers!).

1. PowerPoint 2007 has an option under the Insert ribbon called “Photo Album.” This will bring in many photos at once, into different slides. However, it brings in all the images in 4:3 format. I haven"t found a way to change this. If you change the slide layout of the Photo Album to something else (like 16:9) PowerPoint stretches the images to fit.

3. Once you add your first quote, select the text box and copy it. Then, move to each slide and select “Paste.” This will place a formatted text box on each slide, in the same location from which it was copied. This is a great place to start. One caveat: When pasting your quotes from your word processing program, use “Paste Special” and choose unformatted text. That preserves your text box formatting.

4. My LCD picture frame doesn’t let you change the display time for pictures, and some of the transitions happen too quickly to allow you to read the entire quote. You can do what I did, which was to make two copies of every slide. PowerPoint is creative in its naming; the slides are called Slide1.jpg, Slide2.jpg, et cetera. I named my copies Slide1a.jpg, Slide2a.jpg. The file system sorts the original and the copy together when the files are named this way, so every quote is displayed twice with an intervening transition.

5. If you don’t have a lot slides suitable for quotes, consider visiting a site like Interface Lift, which has a wide range of images in a variety of formats for desktop wallpapers. Chances are, you’ll be able to find images in a format suitable for the native format of your LCD picture frame.

6. Finally, experiment with fonts and type colors. You can even use transparent fills in the text box to make the text stand out a bit more if your slide has a complex background.

There are two points we have to emphasize:Outer Dimension and Main Application. There are the most important factors and it is necessary for us to know them. If we don’t even know the outer dimension and the main application, we don’t know where to start.

This project is created byDIYODE Magazineand is originally published onDIYODE Magazinewhere they also did an informative review on Seeed Studio"s Wio Terminal. I personally love this project and decided to share it here on Hackster. Please do note the following documentation is written byDIYODE Magazine Team.

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.

If you’re new to programming, this code may appear daunting, but it’s really just our Wio Terminal pretending to be a computer sending a web request and reading the response. An API is just an ‘application programming interface’ and is a fancy way of saying it’ll be the source of our data.

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.

The ‘wasPressed’ variable will be used during the main loop to ensure we only display one new quote when the button is pressed, and not to continue looking for quotes when the button is held. This is typically referred to as state detection, and we’ll talk about this shortly.void setup() {

Our setup code is verbose but should be fairly self-explanatory as we read through it. We’re starting the TFT screen and setting its rotation, background settings and a placeholder text while we wait for a connection to the WiFi.

To make the WiFi and networking features work, you’ll need to reflash the WiFi firmware on the Wio Terminal. The official Seeed guide can be found here:https://wiki.seeedstudio.com/Wio-Terminal-Wi-Fi/

It’s not as difficult as it sounds, and it only took us 10 minutes. If you’re wondering why the WiFi isn’t working on your Wio Terminal, there’s a good chance that this will fix the problem.

Also notice that there is a considerable number of calls to the Serial command, which essentially allows us to debug and inspect the functionality of the Wio Terminal by opening the Serial Monitor (Shortcut – Ctrl+Shift+M).void loop() {

This is where the real heavy lifting happens! In our loop function, we’re using that ‘wasPressed’ variable mentioned before to respond only when the button is pressed, and not continuously held.

The getQuoteResponse() function is where the request actually happens, which consists of opening our URL (feel free to visit the URL shown, it will show a random programming quote in your browser), and loading it from a JSON format. We won’t go into JSON formats and the specifics of it in this project, but essentially its a field and value-based system where attributes are given names. Our response usually comes in this format:{"id":"5a6ce86f2af929789500e824","author":"Ken Thompson","en":"One of my most productive days was throwing away 1,000 lines of code."}

In this case, if we refer to the field “author”, it’s value is “Ken Thompson”. That’s why in our code, we can refer to fields to get their values.int len = 23;

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!

We’re all done! Now just hit the upload button, ensuring that the Wio Terminal is switched on. After a couple of seconds of letting it connect to our WiFi…

…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.

OK, this is the sketch that I used to try out user-defined characters on a four-row, 20 character LCD. If you have a two-row LCD, you"ll have to change the calls to "drawbar" in the main loop. You"ll need a potentiometer with the track connected to 0V and 5V, and the wiper connected to analog in 0. Turn (or slide) the pot to see the bar extend across the LCD. The crucial command to the LCD is 0x40, which is used to position the "cursor" in the CGRAM, which is where the user-defined characters are stored. A call to "home" is required after defining the characters, to put the cursor back into the main display memory. All this is documented in the HD44780 data sheet.

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:

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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.

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.

When looking closely at the array, you will see the following. Each row consists of 5 numbers corresponding to the 5 pixels in a 5 x 8 dot character. A 0 means pixel off and a 1 means pixel on.

It is possible to edit each row by hand, but I recommend using this visual tool on GitHub. This application automatically creates the character array and you can click on the pixels to turn them on or off.

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.

From Figure 3 above we can see that the DDRAM controller should have a memory map of 104 bytes (00H to 67H = 68H = 104D), but the location that can be used is only 80 bytes 00H-27H (40 bytes) and 40H-67H (40 bytes); Note that the 28H-3FH address (24 location) is not visible.

LCD connected to this controller will adjust itself to the memory map of this DDRAM controller; each location on the LCD will take 1 DDRAM address on the controller. Because we use 2 × 16 type LCD, the first line of the LCD will take the location of the 00H-0FH addresses and the second line will take the 40H-4FH addresses of the controller DDRAM; so neither the addresses of the 10H-27H on the first line or the addresses of the 50H-67H on the second line on DDRAM is used.

To be able to display a character on the first line of the LCD, we must provide written instructions (80h + DDRAM address where our character is to be displayed on the first line) in the Instruction Register-IR and then followed by writing the ASCII code of the character or address of the character stored on the CGROM or CGRAM on the LCD controller data register, as well as to display characters in the second row we must provide written instructions (C0H + DDRAM address where our character to be displayed on the second line) in the Instructions Register-IR and then followed by writing the ASCII code or address of the character on CGROM or CGRAM on the LCD controller data register.

As mentioned above, to display a character (ASCII) you want to show on the LCD, you need to send the ASCII code to the LCD controller data register-DR. For characters from CGROM and CGRAM we only need to send the address of the character where the character is stored; unlike the character of the ASCII code, we must write the ASCII code of the character we want to display on the LCD controller data register to display it. For special characters stored on CGRAM, one must first save the special character at the CGRAM address (prepared 64 addresses, namely addresses 0–63); A special character with a size of 5 × 8 (5 columns × 8 lines) requires eight consecutive addresses to store it, so the total special characters that can be saved or stored on the CGRAM addresses are only eight (8) characters. To be able to save a special character at the first CGRAM address we must send or write 40H instruction to the Instruction Register-IR followed by writing eight consecutive bytes of the data in the Data Register-DR to save the pattern/image of a special character that you want to display on the LCD [9, 10].

We can easily connect this LCD module (LCD + controller) with MCS51, and we do not need any additional electronic equipment as the interface between MCS51 and it; This is because this LCD works with the TTL logic level voltage—Transistor-Transistor Logic.

The voltage source of this display is +5 V connected to Pin 2 (VCC) and GND power supply connected to Pin 1 (VSS) and Pin 16 (GND); Pin 1 (VSS) and Pin 16 (GND) are combined together and connected to the GND of the power supply.

Pins 7–14 (8 Pins) of the display function as a channel to transmit either data or instruction with a channel width of 1 byte (D0-D7) between the display and MCS51. In Figure 6, it can be seen that each Pin connected to the data bus (D0-D7) of MCS51 in this case P0 (80h); P0.0-P0.7 MCS-51 connected to D0-D7 of the LCD.

Pins 4–6 are used to control the performance of the display. Pin 4 (Register Select-RS) is in charge of selecting one of the 2 display registers. If RS is given logic 0 then the selected register is the Instruction Register-IR, otherwise, if RS is given logic 1 then the selected register is the Data Register-DR. The implication of this selection is the meaning of the signal sent down through the data bus (D0-D7), if RS = 0, then the signal sent from the MCS-51 to the LCD is an instruction; usually used to configure the LCD, otherwise if RS = 1 then the data sent from the MCS-51 to the LCD (D0-D7) is the data (object or character) you want to display on the LCD. From Figure 6 Pin 4 (RS) is connected to Pin 16 (P3.6/W¯) of MCS-51 with the address (B6H).

Pin 5 (R/W¯)) of the LCD does not appear in Figure 6 is used for read/write operations. If Pin 5 is given logic 1, the operation is a read operation; reading the data from the LCD. Data will be copied from the LCD data register to MCS-51 via the data bus (D0-D7), namely Pins 7–14 of the LCD. Conversely, if Pin 5 is given a voltage with logical 0 then the operation is a write operation; the signal will be sent from the MCS51 to LCD through the LCD Pins (Pins 7–14); The signal sent can be in the form of data or instructions depending on the logic level input to the Register Select-RS Pin, as described above before if RS = 0 then the signal sent is an instruction, vice versa if the RS = 1 then the signal sent/written is the data you want to display. Usually, Pin 5 of the LCD is connected with the power supply GND, because we will never read data from the LCD data register, but only send instructions for the LCD work configuration or the data you want to display on the LCD.

Pin 6 of the LCD (EN¯) is a Pin used to enable the LCD. The LCD will be enabled with the entry of changes in the signal level from high (1) to low (0) on Pin 6. If Pin 6 gets the voltage of logic level either 1 or 0 then the LCD will be disabled; it will only be enabled when there is a change of the voltage level in Pin 6 from high logic level to low logic level for more than 1000 microseconds (1 millisecond), and we can send either instruction or data to processed during that enable time of Pin 6.

Pin 3 and Pin 15 are used to regulate the brightness of the BPL (Back Plane Light). As mentioned above before the LCD operates on the principle of continuing or inhibiting the light passing through it; instead of producing light by itself. The light source comes from LED behind this LCD called BPL. Light brightness from BPL can be set by using a potentiometer or a trimpot. From Figure 6 Pin 3 (VEE) is used to regulate the brightness of BPL (by changing the current that enters BPL by using a potentiometers/a trimpot). While Pin 15 (BPL) is a Pin used for the sink of BPL LED.

4RSRegister selector on the LCD, if RS = 0 then the selected register is an instruction register (the operation to be performed is a write operation/LCD configuration if Pin 5 (R/W¯) is given a logic 0), if RS = 1 then the selected register is a data register; if (R/W¯) = 0 then the operation performed is a data write operation to the LCD, otherwise if (R/W¯) = 1 then the operation performed is a read operation (data will be sent from the LCD to μC (microcontroller); it is usually used to read the busy bit/Busy Flag- BF of the LCD (bit 7/D7).

5(R/W¯)Sets the operating mode, logic 1 for reading operations and logic 0 for write operations, the information read from the LCD to μC is data, while information written to the LCD from μC can be data to be displayed or instructions used to configure the LCD. Usually, this Pin is connected to the GND of the power supply because we will never read data from the LCD but only write instructions to configure it or write data to the LCD register to be displayed.

6Enable¯The LCD is not active when Enable Pin is either 1 or 0 logic. The LCD will be active if there is a change from logic 1 to logic 0; information can be read or written at the time the change occurs.

Display brilliant colors on the Displaytech 3.5 inch TFT LCD module! This LCD display has 320 x 240 RGB resolution and uses the NewVision NV3035C single chip digital driver. The TFT driver IC supports 16M colors allowing for a range of hues to be displayed and can also support up to 22 different types of input video formats within RGB, CCIR656, and CCIR601 video formats. The 3.5” TFT is available with a touch screen panel in either resistive (single-finger or stylus pressure) or capacitive (five-finger, multi-gesture) touchscreen technology.

9. Since LCD itself is not luminiferous, the design of Backlight System, which is valuable in both theory and application, becomes the focus of the research in display and imaging domain.

14. In achieving the LCD: Chinese character display (different way of model), light stick, rolling and display digital map display and a series of functions.

18. Introduces the SED1330 LCD controller used in the design of instrumentation, and it"s application of character mode to display chinese[sentencedict.com], and relevant program design.

19. The modern looking dials are clear and easy to read with the 2009 model year update seeing the LCD trip computer that displays average fuel economy and the outside temperature.

20. Note: You may exit the configuration mode without making changes by pressing the STOP button repeatedly until the initial bootstrap loader message reappears on the LCD screen.

25. In this chapter the paper also introduces the method of measure and correction GAMMA curve, put forward the framework of LCD TV display characteristic measurement and correction system.

26. The intelligence vortex flowmeter system is consisted of vortex sensor, temperature sensor, pressure sensor, LCD module and master controller, etc.

27. The hardware design of speech terminal is simple with a LCD module, while the user interface is more beautiful with the technology of chinese character and menu display.

28. Now that Apple iPad has paved the way, e-reader makers could also be re-evaluating the LCD as an alternative to the bistable, low-power but black-and-white E Ink display.

29. Moire pattern caused by the cascade of periodic structures of LCD, Fresnel lens, and Lenticular lens, etc. is a key concern in designing a high quality LCD rear projection screen.

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.

We have used strings already a few times. Each time when we used a “Serial.print() ” or “Serial.println() “, we actually already used strings. Remember that a text in C needs to be enclosed in double quotes? That would make it a string.

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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.

What this does, is create an array of characters (which is a string), the empty square brackets basically says “compiler! Go figure out yourself how large this array should be“. If we would have entered a number, then that number should at least be big enough to hold our string plus one NULL character.

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.

The variable “Name” points to the memory location of the “H” character of the string, which is at position 0 (zero) and therefor has “0” as it’s index number.

If we send address the whole variable, “Name”, then it would return the address of “Name[0]” but your program will keep pulling up the next index, and the next, and the next, until it reaches that NULL character. So in the end, it will return the text of the string.

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).

Unfortunately this makes things more complicated, and we’d have to assign each character to the proper element. Thank goodness there is a function for that: strcpy() .

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Now sometimes we’d like to print for example double quotes, but just typing them into a string will not work – the string would break. The compiler will think you’re done after seeing the second double quotes and everyting remaining will become an unclear mess.

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 first line shows us the wrong way of doing it. The keywords of importance are printed in orange en the string in a green-like color. But … our string has a chunk of black text in it. The word “guest” is black. It means that this is not part of the string, which is caused by the double quotes around the word “guest”.

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");

This trick has to be used for certain other characters as well, for example starting a new line is an ASCII character (see the character table, and look in the “Esc” column). If we’d like to place a line break (start a new line) in our string, then we would need ASCII character 10, which we write as “\n”.

The error message  invalid conversion from "const char*" to "char"  tells us that we are assigning the wrong kind of datatype to our array element. In simple words: This is because we are trying to assign a string to a character.

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).

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“strlen()” (read as: String Length) takes one parameter, a string, and returns the number of characters in the string. It will however not count the NULL character at the end.

“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?

For one; everything is logically grouped together. There is no confusion to what item the properties or functions belong. So when we aks for properties or call a method (function) of a given object “car” then we know it only relates that that specific car.

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.

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”!!!

Line 10 could also be written as Name = String("Bram"); , which will actually work as well, but now we assign the new object (holding the string “Bram”) to the old object, versus the method in the code where we assign just a string to the object.

Now let’s make that string longer, in the previous example, when using the array of char “string”, we noticed that we had to pay attention to the size of the array, so we wouldn’t go beyond it’s capacity. The “String” object however saves us that worry. It corrects automatically.

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.

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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”.

In line 14, we call the method “concat()” to concatenate ” has two nephews, called Bram and Max!” to the original string “Hans”. As you can see, this works right away. But … there is an easier way to glue an extra string to your “String” object by simply using the plus symbol (+), even the compound operator “+=” works. See lines 27 and 28, where we use “+=” and even the regular “+”.

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”)

When comparing the two strings, it will actually compare the ASCII values. So when it returns a number greater than zero, it actually means that it ran into a character which has a greater ASCII value compared to the other character, in the same position in the other string, and this can be confusing, because we humans would expect “Hans” to be greater than “Hi” – but its not. This is in part also because we humans see the longer string “Hans” as the larger one of the two.

Comparing “String” objects result in the same kind of confusion, but instead of using the “strcmp()” function, we can use the simple comparison operators.

If you have questions, just ask them below in the comment section, and keep in mind: There are no stupid questions! We all had to start at some point!

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.

In the code below, the asterisk after the datatype char "char*" indicates that this is an array of "pointers". All array names are actually pointers, so this is required to make an array of arrays. Pointers are one of the more esoteric parts of C for beginners to understand, but it isn"t necessary to understand pointers in detail to use them effectively here.

Most of the time we use the serial plotter of the Arduino IDE to visualize our solutions or output of a sketch. This is great and a big time saver when you are doing prototyping. But there is a time when your system will go live. If you are for example only sending data from sensors to a database on a Raspberry Pi, than you are able to view the output remote from your PC by connecting to the database. But there are use cases like an indoor weather station, where you want to see the output like the current temperature directly and not when you are on you PC.

Than displays are the way to go. There are different kinds of displays like 7 Segment LED display, 4 Digit 7 Segment display, 8×8 Dot Matrix display, OLED display or the easiest and cheapest version the liquid crystal display (LCD).

Most LCD displays have either 2 rows with 16 characters per row or 4 rows with 20 characters per row. There are LCD screen with and without I2C module. I highly suggest the modules with I2C because the connection to the board is very easy and there are only 2 instead of 6 pins used. But we will cover the LCD screen with and without I2C module in this article.

The following table gives you an overview of all components and parts that I used for this tutorial. I get commissions for purchases made through links in this table.

The LCD display has an operating voltage between 4.7V and 5.3V with a current consumption of 1mA without backlight and 120mA with full backlight. There are version with a green and also with a blue backlight color. Each character of the display is build by a 5×8 pixel box and is therefore able to display custom generated characters. Because each character is build by (5×8=40) 40 pixels a 16×2 LCD display will have 16x2x40= 1280 pixels in total. The LCD module is able to operate in 8-bit and 4-bit mode. The difference between the 4-bit and 8-bit mode are the following:

If we use the LCD display version without I2C connection we have to add the potentiometer manually to control the contrast of the screen. The following picture shows the pinout of the LCD screen.

Also I added a table how to connect the LCD display with the Arduino Uno and the NodeMCU with a description of the LCD pin. To make it as easy as possible for you to connect your microcontroller to the display, you find the corresponding fritzing connection picture for the Arduino Uno and the NodeMCU in this chapter.

3VEEPotentiometerPotentiometerAdjusts the contrast of the display If this pin is grounded, you get the maximum contrast. We will connect the VEE pin to the potentiometer output to adjust the contrast by changing the resistance of the potentiometer.

4RSD12D2Select command register to low when we are sending commands to the LCD like set the cursor to a specific location, clear the display or turn off the display.

7Data Pin 0 (d0)Connected to microcontroller pin and toggled between 1 and 0 for data acknowledgement. So if we want to send data via the data pins 0 to 7, we have to make sure that the enable pin is high.

8Data Pin 1 (d1)Data pins 0 to 7 forms an 8-bit data line. The Data Pins are connection to the Digital I/O pins of the microcontroller to send 8-bit data. These LCD’s can also operate on 4-bit mode in such case Data pin 4,5,6 and 7 will be left free.

Of cause we want to try the connection between the microcontroller and the LCD display. Therefore you find an example sketch in the Arduino IDE. The following section shows the code for the sketch and a picture of the running example, more or less because it is hard to make a picture of the screen ;-). The example prints “hello, world!” in the first line of the display and counts every second in the second row. We use the connection we described before for this example.

Looks very complicated to print data onto the LCD screen. But don’t worry like in most cases if it starts to get complicated, there is a library to make the word for us. This is also the case for the LCD display without I2C connection.

Therefore the next step is to install the library “LiquidCrystal”. You find here an article how to install an external library via the Arduino IDE. After you installed the library successful you can include the library via: #include < LiquidCrystal.h>.

Like I told you, I would suggest the LCD modules with I2C because you only need 2 instead of 6 pins for the connection between display and microcontroller board. In the case you use the I2C communication between LCD and microcontroller, you need to know the I2C HEX address of the LCD. In this article I give you a step by step instruction how to find out the I2C HEX address of a device. There is also an article about the I2C communication protocol in detail.

On the backside is a 10 kΩ potentiometer build in to control the screen contrast. You do not have to add the potentiometer manually like in the version without I2C connection.

The following picture shows how to connect an I2C LCD display with an Arduino Uno. We will use exact this connection for all of the examples in this article.

To use the I2C LCD display we have to install the required library “LiquidCrystal_I2C” by Frank de Brabander. You find here an article how to install an external library via the Arduino IDE. After you installed the library successful you can include the library via: #include < LiquidCrystal_I2C.h>.

The LiquidCrystal library has 20 build in functions which are very handy when you want to work with the LCD display. In the following part of this article we go over all functions with a description as well as an example sketch and a short video that you can see what the function is doing.

LiquidCrystal_I2C()This function creates a variable of the type LiquidCrystal. The parameters of the function define the connection between the LCD display and the Arduino. You can use any of the Arduino digital pins to control the display. The order of the parameters is the following: LiquidCrystal(RS, R/W, Enable, d0, d1, d2, d3, d4, d5, d6, d7)

If you are using an LCD display with the I2C connection you do not define the connected pins because you do not connected to single pins but you define the HEX address and the display size: LiquidCrystal_I2C lcd(0x27, 20, 4);

xlcd.begin()The lcd.begin(cols, rows) function has to be called to define the kind of LCD display with the number of columns and rows. The function has to be called in the void setup() part of your sketch. For the 16x2 display you write lcd.begin(16,2) and for the 20x4 lcd.begin(20,4).

xxlcd.clear()The clear function clears any data on the LCD screen and positions the cursor in the upper-left corner. You can place this function in the setup function of your sketch to make sure that nothing is displayed on the display when you start your program.

xxlcd.setCursor()If you want to write text to your LCD display, you have to define the starting position of the character you want to print onto the LCD with function lcd.setCursor(col, row). Although you have to define the row the character should be displayed.

xxlcd.print()This function displays different data types: char, byte, int, long, or string. A string has to be in between quotation marks („“). Numbers can be printed without the quotation marks. Numbers can also be printed in different number systems lcd.print(data, BASE) with BIN for binary (base 2), DEC for decimal (base 10), OCT for octal (base 8), HEX for hexadecimal (base 16).

xlcd.println()This function displays also different data types: char, byte, int, long, or string like the function lcd.print() but lcd.println() prints always a newline to output stream.

xxlcd.display() / lcd.noDisplay()This function turn on and off any text or cursor on the display but does not delete the information from the memory. Therefore it is possible to turn the display on and off with this function.

xxlcd.scrollDisplayLeft() / lcd.scrollDisplayRight()This function scrolls the contents of the display (text and cursor) a one position to the left or to the right. After 40 spaces the function will loops 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, than the scrolling text function is very handy. First the substring with the maximum of characters per line is printed, moving the start column from the right to the left on the LCD screen. Than the first character is dropped and the next character is printed to the substring. This process repeats until the full string is displayed onto the screen.

xxlcd.autoscroll() / lcd.noAutoscroll()The autoscroll function turn on or off the functionality that each character is shifted by one position. The function can be used like the scrollDisplayLeft / scrollDisplayRight function.

xxlcd. leftToRight() / lcd.rightToLeft()The leftToRight and rightToLeft functions changes the direction for text written to the LCD. The default mode is from left to right which you do not have to define at the start of the sketch.

xxlcd.createChar()There is the possibility to create custom characters with the createChar function. How to create the custom characters is described in the following chapter of this article as well as an example.

xlcd.backlight()The backlight function is useful if you do not want to turn off the whole display (see lcd.display()) and therefore only switch on and off the backlight. But before you can use this function you have to define the backlight pin with the function setBacklightPin(pin, polarity).

xlcd.moveCursorLeft() / lcd.moveCursorRight()This function let you move the curser to the left and to the right. To use this function useful you have to combine it with lcd.setCursor() because otherwise there is not cursor to move left or right. For our example we also use the function lcd.cursor() to make the cursor visible.

xlcd.on() / lcd.off()This function switches the LCD display on and off. It will switch on/off the LCD controller and the backlight. This method has the same effect of calling display/noDisplay and backlight/noBacklight.

To show you some basic examples of the LiquidCrystal and LiquidCrystal_I2C library, you can copy the following example that shows three different functions of the library:

Show or hide a cursor (“_”) that is useful when you create a menu as navigation bar from the left to the right or from the top to the bottom, depending on a horizontal of vertical menu bar. If you are interested how to create a basic menu with the ESP or Arduino microcontroller in combination with the display, you find here a tutorial.

The following code shows you the Arduino program to use all three LCD display functions of the library divided into three separate functions. Also the video after the program shows the functions in action.

The creation of custom characters is very easy if you use the previous mentioned libraries. The LiquidCrystal and also the LiquidCrystal_I2C library have the function “lcd.createChar()” to create a custom character out of the 5×8 pixels of one character. To design your own characters, you need to make a binary matrix of your custom character from an LCD character generator or map it yourself. This code creates a wiggling man.

In the section of the LCD display pinout without I2C we saw that if we set the RS pin to how, that we are able to send commands to the LCD. These commands are send by the data pins and represented by the following table as HEX code.

I hope you learned a lot in this article. Feel free to test the example sketches with your microcontroller. Do you have any questions regarding this article? Use the comment section below and I will answer your question.

Display Logic offers a number of LCD interfaces with a va