how to program lcd display arduino brands

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Arduinos are popular microcontroller boards and a common desired functionality is to use them to drive LCD screens, usually to relay information to the user. In this tutorial, I will teach you how to use the Adafruit I2C/SPI LCD Backpack with an Arduino microcontroller board to drive a LCD.

LCDs require many connections to a driver to work. Managing all these connections all the time can become both cumbersome and annoying. Luckily, Adafruit has made an I2C/SPI LCD Backpack that works with most LCDs. This backpack conveniently reduces the number of connections between your microcontroller and the LCD to 4.

I always like to make a wiring diagram (Figure 1: Arduino-LCD Schematic) using Fritzing, an open-sources schematic capture and PCB routing software. You can download Fritzing using the following link (optional): http://fritzing.org/home/

Pin 1 on the LCD goes to Pin 1 on the LCD Backpack. The rest of the pins are wired sequentially. This can be done on a breadboard or the backpack can be soldered to LCD as I have done.

I2C and SPI are two very popular serial interface buses. This tutorial covers interfacing your Arduino to the LCD Backpack using I2C, but the LCD Backpack can interface with SPI too. You can set the I2C address (A0, A1, A2) or enable SPI (SPI Enable) by jumpering the solder jumpers on the backpack (Figure 2: Solder Jumpers on LCD Backpack). The only circuit using I2C in the tutorial is the LCD Backpack, so we do not need to change the current configurations. This means the LCD Backpack will have an I2C address of 0 (0x00).

To interface the LCD Backpack to the Arduino, connect 5V and a ground pin on the Arduino to the 5V and ground pin on the LCD Backpack. This will provide the LCD and LCD Backpack with power. Note: The LCD requires 5V minimum to work properly. The next two connections are serial data and serial clock. The serial clock connection (orange wire) is between the SCL pin on the Arduino and the CLK pin on the backpack. The serial data connection (blue wire) is between the SDA pin on the Arduino and the DAT pin on the backpack.

The first part of the code is to include the Adafruit_LiquidCrystal header file. This allows you to use the functions in this library. Because the Adafruit_LiquidCrystal library is automatically downloaded with Arduino IDE, this tutorial doesn’t cover downloading Arduino libraries.

Before writing to the LCD, it needs to be initialized. The “begin” function does this by telling the LCD Backpack how many characters are on the display. Since the LCD I am using has a backlight, I also turn the backlight on.

Now that the LCD is initialized, I write “Test Code” to check that everything is working. This code sets the cursor to a starting position, writes “Test” to the display, waits 2 seconds, and then clears the display.

The loop part of the code uses the millis() function and divides by 1000 to compute how long the program has been running. The code then uses the print and setCursor functions to display the program time across the LCD. The loop then waits a second before repeating.

Upload the code to the Arduino. Make sure the Arduino is connected using the 9V Power Adapter because power over USB is not sufficient to power both the Arduino and the LCD display. Once the program begins you should see “Test” across the LCD display as the program runs through setup (Figure 2: LCD Displaying “Test”). When the program loop begins you will see the time program displayed and updating every second (Figure 3: LCD Display Program Runtime – 8(s)). Congrats! You now have an easy-to-use LCD screen for your Arduino board and can use it as a display for future projects. A tip to keep in mind: I2C is a slow bus and if you are constantly updating your LCD you will take time away from the controller performing other tasks.

Liquid Crystal displays or LCDs have been used in electronics equipment since the late 1970s.   LCD displays have the advantage of consuming very little current And they are ideal for your Arduino projects.

In this article and in the accompanying video I’ll show you how easy it is to add an LCD display to your next Arduino design. I’ll also show you a very popular Arduino Shield that has a keypad which you can use in your projects as well.

Today LCD displays are used in a variety of items from test equipment to televisions. They’re inexpensive and versatile, this makes them ideal for all sorts of designs.

LCD displays do not emit light. Instead they block the passage of light, like little windows which open and shut the let light through. The liquid crystals used inside LCD displays are sandwiched between two layers of polarized material. By changing the orientation of the liquid crystals they allow light to pass or they block the light entirely.

Because transmissive LCD displays (the type we will be using) work by blocking light they require a backlight. Several methods have been used to create back lights including electroluminescent panels and fluorescent tubes.   these days the most common form of backlight is an LED, in fact so-called LED televisions are usually just LCD screens with an LED backlight system.

Another type of LCD display, the passive-matrix display, does not require a backlight, it works using reflected light. This type of display is often found in digital watches.

The principles of liquid crystals were discovered in the late 1880s but work on Modern LCD displays did not begin until the mid-1960s. a number of patents were filed in the early 1970s and in 1973 the Sharp Corporation introduced LCD displays for calculators.

The first color LCD displays were developed in the early 1980s but production units were not commonly available until the mid-1990s. By the late 1990s LCD displays were quite common.

A number of LCD displays are available for experimenters. These low-cost monochrome displays are ideal for use with microcontrollers like the Arduino and micro computers like the Raspberry Pi.

These displays are available in a number of different configurations. The part number for the display generally relates to the number of rows and columns in the display.

Common display configurations include 16 x 2, 16 x 4 and 20 x 4.  All of these displays are used in a virtually identical fashion the only difference being the number of columns and rows they have.

The LCD1602 display module is a very popular and inexpensive LCD display.  It is available in a number of different colors such as blue yellow and green and can easily be connected to an Arduino or Raspberry Pi.

In operation data is sent down the parallel data lines for the display. There are two types of data that can be sent to the display. The first type of data are the ASCII characters which are to be displayed on the display. The other type of data are the control characters that are used to activate the various display functions.

Brightness– This is the input for the brightness control voltage, which varies between 0 and 5 volts to control the display brightness. On some modules this pin is labeled V0.

Because the LCD module uses a parallel data input it requires 8 connections to the host microcontroller for the data alone. Add that to the other control pins and it consumes a lot of connections.  On an Arduino Uno half of the I/O pins would be taken up by the display, which can be problematic if you want to use the I/O pins for other input or output devices.

In 4-wire mode the data is sent a half a byte at a time, thus requiring only 4 data connections. The upper half of the data input (D4 to D7) is used while the other pins are not connected to anything.

We will begin our experiments by hooking up the LCD1602 to an Arduino Uno and running a few of the example sketches included with the Arduino IDE.  This will allow you to get familiar with the display without needing to write any code.

We need to hookup our LCD display to our Arduino. The display can use any of the Arduino digital I/O pins as it has no special requirements, but if you hook it up as I’ve illustrated here you can run the example sketches without needing to make any modifications.

In addition to the LCD1602 display ands the Arduino Uno you will need a 10K trimpot ot potentiometer, this is used a s a brightness control for the display. You’ll also need a 220 ohm resistor to drop the voltage for the displays LED backlight.

The Arduino IDE includestheLiquidCrystallibraryand this library has a number of example sketches. I’ll go over three of them here but you can also try the other ones.

The sketch starts with a number of credits and a description of the required hardware hookup. You’ll note that this is the same hookup you just performed on your Arduino and LCD module.

We then initialize an object that we call “lcd” using the pinouts of the LCD display. If you decide to hook up your display to different pins then you’ll need to modify this section.

In the beginning of the loop we set our cursor to the first position in the second row. Note that the row numbers start with zero so the second row is row 1.

That ends the loop, so we start back at the top of the loop and repeat. The result will be a counter on the second line that counts seconds from the htime the Arduino was last reset.

Load the sketch up to your Arduino and observe your display. If you don’t see anything try adjusting the brightness control that you wired to the display.

The second example we will try isthe Scroll sketch. Scrolling is a useful technique when you can’t get your text to fit on one line of the LCD display.

In the loop the code demonstrates the use of thescrollDisplayLeftandscrollDisplayRightfunctions.  As their names imply they move the text in a left or right direction.

Finally the last counter moves the text 16 positions to the left again, which will restore it back to the center of the display. The loop then repeats itself.

Custom characters are useful when you want to display a character that is not part of the standard 127-character ASCII character set. Thi scan be useful for creating custom displays for your project.

A character on the display is formed in a 5 x 8 matrix of blocks so you need to define your custom character within that matrix. To define the character you’ll use thecreateCharfunctionof the LiquidCrystal library.  You are limited to defining a maximum of eight characters.

To usecreateCharyou first set up an array of bytes with 8 elements.  Each element in the array defines one row of the character in the 5 x 8 matrix.  You then use createCharto assign a number from 0 to 7 to that array.

The Custom Character demonstration requires one additional component to be wired to the Arduino, a potentiometer (10K or greater) wired up to deliver a variable voltage to analog input pin A0.

As with the previous sketches we examined this one starts by loading theLiquidCrystallibrary and defining an object calledlcdwith the connection information for the display.  It then moves on to define the custom characters.

The last two arrays,amsUpandarmsDowndefine the shape of a little “stickman”, or “stickperson” if you want to be politically correct! This is done to show how we can animate a character on the display.

Then the five custom characters are assigned a unique integer using the createChar function. Remember, you can define a maximum of eight custom characters in a sketch.

Finally the setup routine ends by printing a line to the first row of the LCD display. The line makes use of two of the custom characters, the “heart” and the “smiley”.

We begin by reading the value of the voltage on pin A0 using the ArduinoanalogReadfunction. As the Arduino has a 10-bit analog to digital converter this will result in a reading ranging from 0 to 1023.

We then use an Arduinomapfunction to convert this reading into a range from 200 to 1000. This value is then assigned to an integer calleddelayTime, which as its name implies represents a time delay period.

One thing you may have noticed about using the LCD display module with the Arduino is that it consumes a lot of connections. Even in 4-wire mode there are still a total of seven connections made to the Arduino digital I/O pins. As an Arduino Uno has only 14 digital I/O pins that’s half of them used up for the display.

In other cases you would need to resort to using some of the analog pins as digital pins or even moving up to an Arduino Mega which has many more I/O pins.

But there is another solution. Use the I2C bus adapter for the LCD display and connect using I2C.  This only consumes two I/O pins and they aren’t even part of the set of digital I/O pins.

The I2C or IIC bus is theInter Integrated Circuitbus. It was developed by Philips Semiconductors in 1982 for use in the television industry.  The idea was to allow the integrated circuits in televisions to “talk” to one another using a standard bus.

The bus has evolved to be used as an ideal method of communicating between microcontrollers, integrated circuits, sensors and micro computers.  You can use it to allow multiple Arduinos to talk to each other, to interface numerous sensors and output devices or to facilitate communications between a Raspberry Pi and one or more Arduinos.

In I2C communications there is the concept of Master and Slave devices. There can be multiples of each but there can only be one Master at any given moment. In most Arduino applications one Arduino is designated Master permanently while the other Arduinos and peripherals are the Slaves.

The Master transmits the clock signal which determines how fast the data on the bus is transferred. There are several clock speeds used with the I2C bus. The original design used 100 KHz and 400 KHz clocks.  Faster rates of 3.4 MHz and higher are available on some I2C configurations.

Every device on the I2C bus has a unique address. When the Master wants to communicate with a Slave device it calls the Slaves address to initiate communications.

The I2C Adapter for the LCD display is a tiny circuit board with 16 male header pins soldered to it. These pins are meant to be connected directly to the 16-pin connection on the LCD1602 display (or onto other displays that use the same connection scheme).

The device also has a 4-pin connector for connection to the I2C bus. In addition there is a small trimpot on the board, this is the LCD display brightness control.

Most of these devices have three jumpers or solder pads to set the I2C address. This may need to be changed if you are using multiple devices on the same I2C bus or if the device conflicts with another I2C device.

Most Arduino Unos also have some dedicated pins for I2C, these are internally connected to A4 and A5 and are usually located above the 14 digital I/O pins.  Some models of the Uno have additional I2C connectors as well.

Note how much easier it is to use the I2C connection, which does not consume any of the Arduino Unos 14 digital I/O pins. Since A4 and A5 are being used for the I2C bus they can’t be used as analog inputs in this configuration.

If you don’t know the address you’ll need to find it out before you can run the sketches I’m about to show you. Fortunately there is a simple way of doing this, thanks to the great work of Nick Gammon.

Nick has written a simple I2C scanner sketch that he’s put into the public domain. It scans your I2C bus and gives you back the address of every I2C device it finds.  I’ve repeated Nick’s sketch here, it’s also in the ZIP file that you can download with all of the code for this article.

Load this sketch into your Arduino then open your serial monitor. You’ll see the I2C address of your I2C LCD display adapter. You can then make note of this address and use it in the sketches we’ll be looking at now.

In order to run the subsequent sketches you’ll need to install another library. This is theNewLiquidCrystallibrarywhich, as its name implies, is an improved version of the LiquidCrystal library packaged with your Arduino IDE.

This library includes libraries for running the I2C adapter, which is why we are going to use it. But ist also can be used as a replacement for the original LiquidCrystal library and it offers improved performance over the original.

Remember that you’ll need to know the address of your I2C adapter before you run this sketch, so if you don’t know it go back and run Nick Gammon’s I2C Scanner first.

The sketch starts by loading the ArduinoWirelibrary. This is the Arduino library that facilitates communications over I2C and it’s part of your Arduino IDE installation.

On the next line we define the connections to the LCD display module from the I2C Adapter,. Note that these are NOT the connections from the Arduino, they are the connections used by the chip on the adapter itself.

In setup we set the size of the display and then print “Hello world!” on the first line in the first position.  After a short delay we print “How are you?” on the second line.

The next demo uses theautoscrollfunction to scroll some text.  We first print the text “Scroll demo – “ and then implement a counter to count from 0 to 9 while scrolling the text.

Load the sketch and run it on your Arduino. If you can’t get it to work check out the address and connection information to be sure you have it right.

In this project we will put together a digital temperature and humidity gauge.  It’s pretty accurate thanks to the use of a DHT22 temperature and humidity sensor. You could also substitute a cheaper DHT11 sensor but it won’t be as accurate.

We need to make a minor wiring adjustment to the hookup with our I2C adapter, specifically we will need to add a DHT22 temperature and humidity sensor into the circuit. The wiring is shown here:

As you can see the DHT22 is connected with its output tied to pin 7 of the Arduino. The other two connections are 5 volts and ground. Note that pin 3 of the DHT22 is not used.

This sketch also makes use of theDHTlibrary from Adafruit. We used this library in a previous article, “Using the HC-SR04 Ultrasonic Distance Sensor with Arduino” so you may want to take a look at that one in order to get it installed.

The key thing to note is that this library is dependant upon another Adafruit library, theirUnified Sensorlibrary. Both can be installed using the Library Manager in your Arduino IDE.

The sketch is similar to our demo sketch in that it creates an “lcd” object with the I2C and display connection information.  It also defines a couple of parameters for the DHT22 sensor, as well as some floating variables to hold the temperature and humidity values.

Note that this displays the temperature in Celsius. If you want to change this to Fahrenheit its a simple matter of using some math. The formula( temp * 1.8 ) + 32will convert the results to Fahrenheit.

So far we have used the LCD1602 display module for all of our experiments. For our final demonstration we’ll switch to a popular Arduino shield that contains a LCD1602 along with some push buttons.

The LCD Keypad Shield is available from several different manufacturers. The device fits onto an Arduino Uno or an Arduino Mega and simplifies adding an LCD display to your project.

The Reset button is simply connected to the Arduino Reset pin and works just like the Reset button on the Arduino itself. This is common on many shields as the shields physically cover the Reset button.

The other five push buttons can really be used for anything you’d like to use them for. And the way they are hooked up is very interesting, at least it is to me!

Instead the buttons are connected to a resistor array that acts as a voltage divider. The entire array is connected to the Arduino’s analog A0 pin.  One pin for five push buttons.

Pressing each button will send a voltage to the analog A0 pin. Because of the arrangement of the resistors each button will send a different voltage to the analog pin. By measuring the voltage level you can determine which button was pressed.

Note that the LCD is being used in 4-wire mode. The LCD itself is the same one used on the LCD1602 module, so all of the code for that module will work with the LCD Keypad Shield as well.

Now that you know how the LCD Keypad module works and which Arduino pins it uses all that remains is to install it onto your Arduino and load the demo sketch.

One thing – once the shield is installed on the Arduino you won’t have easy access to the unused I/O pins to connect any sensors or output devices you may want to use (although the demo sketch doesn’t need anything else connected).  There are a couple of ways to get around this:

Use a shield that exposes the pins for prototyping before you install the LCD Keypad shield. In the video associated with this article I use a “Screw Shield” that brings all of the Arduino I/O pins out to a series of screw connectors. There are other similar shields. Using one of these shields is the easiest way to work with the LCD Keypad shield, as well as other Arduino shields.

The sketch begins by including theLiquidCrystallibrary. You can use the original one or the one includes with theNewLiquidCrystallibrary.  We then set up an object with the LCD connections, note that these are just hard-coded as they won’t change.

Next we define a number of constants, one for each of the push buttons. Note that nothing is defined for the Reset button as it simply mimics the Arduino Reset button, however a constant is defined for the “none” condition.

We then define two variables. The first one holds the value of the selected pushbutton, the second holds the analog reading from port A0 where the push button input is detected.

After that we define a function calledread_LCD_buttons().  This function reads the value on analog port A0 and returns an integer corresponding to the button integers we defined earlier. Note that the function adds approximately 50 to each of the manufacturers specified values to account for intolerances in the resistors in the voltage divider.

We start the loop by placing the cursor 9 spaces over on the second line. We then use themillisfunction to display a counter that counts the time since the Arduino was reset. This is to test the Reset button.

We then call ourread_LCD_buttons()function and use it to display the value of the push button, right before the counter. Then we end the loop and do it again.

Load the code onto the Arduino and run it. You should see the value of each button as you press it, along with a counter that increments each second. If you press Reset the counter should reset itself back to zero.

As you can see LCD displays are pretty simple to use thanks to the availability of some excellent libraries for the Arduino.  As these displays are also very inexpensive they will make an ideal addition to many of your Arduino projects.

And finally the LCD Keypad Shield is a convenient method of adding both a display and a simple keypad to your project, no wiring or soldering required.

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Hello friend welcome to “Techno-E-Solution” in this article we are going to learn how to connect LCD display with Arduino Uno and print "Hello World!" on LCD using Arduino Uno. The 16x2 LCD is most popular LCD in electronics projects. In upcoming project we need this display in our project so it"s the beginners level tutorial learn this tutorial with fun. So friends let"s get started..........

A PCB Design Problems Detector, An Engineering Solution Provider Import the Gerber file with one click. No need for complicated file reading steps to review easily and improve efficiency.

Hello friends welcome back to Techno-E-solution, In previous video we see how to interface LCD 16×2 to Arduino Uno, but there are very complicated circuits, so in this tutorial, I"ll show you how to reduce circuitry by using I2C module which is very compact & easy to connection. Simply connect I2C module with LCD parallel & connect I2C modules 4 pins to Arduino. I2C module has 4 output pins which contains VCC, GND, SDA, SCL where 5V supply gives to I2C module through VCC & GND to GND of Arduino. SDA is a data pin & SCL is clock pin of I2C module. To interface LCD and I2C with Arduino we need Liquid Crystal I2C Library in Arduino IDE software.

To make this project we need Arduino Liquidcrystal library in Arduino IDE. Follow following steps to add this library in Arduino IDE software.Open Arduino IDE Software.

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Liquid Crystal Display is made use in various kinds of devices from small display screen in calculator to large screens in televisions. There are lots of advantages in using the LCD displays in systems like power efficiency, thin size, low cost etc. LCD based small display modules are normally found in all kinds of embedded devices.The LCD even though looks simple, but it is actually difficult to make it work.

The LCD works with voltage pulses only and that with precise timing and voltage levels. Hence special kinds of LCD drivers are developed to drive the LCD. Two or more of this kind of driver ICs together with the LCD screen forms LCD modules which are normally found in embedded systems.The LCD module makes a system stand-alone which can take input and display the corresponding output. This particular project demonstrates how to interface a 16x2 LCD display with an Arduino board.

Any AVR microcontroller based board which follows the standard Arduino schematic and is flashed with the Arduinobootloadercan be called an Arduino board. There is no other tool available which helps in easy prototyping like the Arduino does.  The Arduino board has all the required circuitary to get the built-in AVR microcontroller running. When it comes to programming the Arduino board anyone who have basic knowledge of c programming can quickly get started with the Arduino IDE. The tutorial onGetting started with Arduinoexplains about the steps required to get start with an Arduino board.The Arduino board used in this project is the Arduino pro-mini board and the IDE version of the Arduino is 1.0.3 for windows. The image of the Arduino pro-mini board and the Arduino IDE are shown below;

Since the Arduino pro-mini board has no circuitary for interfacing it with the serial port or the USB port of the PC, an external USB to TTL converter board is required to connect it with the PC. This hardware helps in programming the Arduino board and also helps in the serial communication with the USB port of the PC.

It is assumed that the reader has gone through the projectand tried out all the things discussed there.The Arduino IDE has so many functions which help one to interface the four bit LCD module. There are functions to initialize the LCD module and to write character characters in the LCD module. The functions used in the coding of this projects are lcd.begin(), and lcd.print(). The functions are available in the library and one should initialize the library before using those functions.

This function should be called to initialize the four bit LCD library and then only the library functions can be called in the code. The function has six parameters which should be provided during a function call as per the circuit connection with the Arduino board and the LCD module. The details of the function parameters are listed in the order below.

For example the following statement can be used to initialize an LCD library for the code written for the circuit in which the RS pin is connected to pin12, Enable pin to 11, and D4, D5, D6 and D7 to pins 5, 4, 3 and 2 resepectievely.

This function can be used to initialize the LCD module. The first parameter is the number of rows of the LCD module in use and the second parameter is the number of columns. The lcd.begin() function can be used to initialize a 16*2 LCD using the statement;

This function is used to display an ASCII character or string in an LCD screen. If a value is provided as the parameter of the function, it will format that value into displayable string and then display it on the LCD.

The lcd.print() function is analogues to the function Serial.print() discussed with the projecton how to do serial debugging with Arduino,how to do serial input and output with Arduinoandhow send serial data from Arduino.

The above statement will print the string “hello world” in the LCD screen. If the value of a variable need to be printed on the LCD screen the same function can be used as it can format a value to the ASCII string representing the value.

The code first includes the library which has all the function required to access the LCD module. The 16*2 LCD module used in this project is initialized using the function lcd.begin(). The function lcd.print() is then used to print data on the LCD module.

The code initializes the module, display a string in the module using the functions available in the library. The code the blinks an LED in an infinite loop using the pinMode () and digitalWrite () functions discussed in the project onandhow to use digital input and output of Arduino.

In the previous tutorial, we discussed multiplexingseven-segment displays(SSDs). Continuing with the display devices, in this tutorial, we will cover how to interface character LCD when using Arduino. Character LCDs are the most common display devices used in embedded systems. These low-cost LCDs are widely used in industrial and consumer applications.

Display devices in embedded systemsMost devices require some sort of display for various reasons. For example, an air-conditioner requires a display that indicates the temperature and AC settings. A microwave oven requires a display to present the selected timer, temperature, and cooking options. A car dashboard uses a display to track distance, fuel indication, mileage, and fuel efficiency. Even a digital watch requires a display to showcase the time, date, alarm, and modes.

The display devices used in embedded circuits — whether they are industrial devices, consumer electronic products, or fancy gadgets — are used either to indicate some information or to facilitate machine-human interface.

For instance,LEDsare used as indicators of mutually exclusive conditions. The SSDs are used to display numeric information. The Liquid Crystal Displays (LCDs), TFTs, and OLED displays are used to present the more complicated information in embedded applications. Often, this complication arises due to the text or graphical nature of the information or the interface.

The character LCDs are used where the information or interface is of a textual nature. The graphical LCDs are used where the information or interface is of a graphical nature. The graphical LCDs that are used to design machine-human interfaces may also have touchscreens.

Character LCDsCharacter LCDs are useful in showing textual information or to provide a text-based, machine-human interface. It’s even possible to display some minimal graphics on these LCDs. These are low-cost LCD displays that fit in a wide range of embedded applications.

Generally, character LCDs do not have touchscreens. And unlike graphical LCDs, these LCDs do not have continuous pixels. Instead, the pixels on character LCDs are arranged as a group of pixels or dot-matrix of pixels of fixed dimensions.

Each dot-matrix of a pixel is intended to display a text character. This group of pixels is usually of 5×7, 5×8, or 5×10 dimensions — where the first digit indicates the number of columns of pixels and the second digit indicates the number of rows of pixels. For example, if each character has 5×8 dimensions, then the character is displayed by illuminating 5 columns and 8 rows of pixels/dots. This may include pixels used to show the cursor.

The character LCDs are classified by their size, which is expressed as the number of characters that can be displayed. The number of possible characters that can display at a time on the LCD is indicated as the number of columns of characters and the number of rows of characters.

The common size of character LCDs is 8×1, 8×2, 10×2, 16×1, 16×2, 16×4, 20×2, 20×4, 24×2, 30×2, 32×2, 40×2, etc. For example, a 16×2 character LCD can display 32 characters at a time in 16 columns and 2 rows. Generally, characters are displayed as a matrix of black dots while the backlight of LCD may be a monochromatic color like blue, white, amber, or yellow-green.

The character LCDs may use any one of these types. The TN types are low-cost but have a narrow viewing angle and low contrast. The FSTN offers the best contrast and widest viewing angle, but they are more costly. Even character LCDs that use the FSTN display are still cheaper in comparison to graphical LCDs, TFTs, and OLEDs.

Most of the character LCDs use LED backlight and the backlight color can be white, blue, amber, or yellow-green. The other types of a backlight in character LCDs include EL, CCFL, internal power, external power, and 3.3 and 5V backlights. EL and LED backlights are the most common. The LCD may have a reflective, trans-reflective, or transmissive rear polarizer.

The quality of display depends on the LCD type, the backlight, and the nature of a rear polarizer used in the LCD panel. When selecting an LCD panel for an embedded application, it’s important to decide on the quality of the LCD display, according to the requirements. This includes per the application, class of the device, nature of use (such as indoor or outdoor), target users of the device, intended user-experience, operating conditions (such as temperature and operating voltage), and cost limitations.

For example, a character LCD that has to be used for the machine-human interface must have better contrast, a wide viewing angle, and a good backlight.

Even on a character LCD, a large number of pixels have to be controlled to display the text. A 16×2 character LCD in which each character is 5×8 pixels means that a total of 1280 pixels (16×2 characters x 5×8 Pixels) have to be controlled. This requires interfacing the pixels across 16 rows (2 rows of characters x 8 rows in each character) and 80 columns (16 columns of characters x 5 columns in each character) of connections.

This is when pixels are black dots and merely require switching either ON or OFF by the controller to display text characters. On a typical microcontroller, there are not these many I/O pins that can be dedicated to controlling the pixels of an LCD panel. That is why LCD modules have integrated controllers that control the pixels of the LCD. The integrated controller can interface with a microcontroller or a processor via an 8-bit/4-bit parallel port or a serial interface (like I2C). The integrated controller receives data and commands from the microcontroller/processor to display text on the LCD panel via a 4-bit/8-bit parallel or serial interface.

In fact, the LCD module is a complete embedded system comprising of an LCD panel, LCD driver, LCD controller, LED Backlight, internal flags, Address Counter, Display Data RAM (DDRAM), Character Generator ROM (CGROM), Character Generator RAM (CGRAM), Data Register (DR), Instruction Register (IR), and Cursor Control Circuit.

1. LCD Panel. The character LCDs have the dot-matrix LCD panel. The text characters are displayed on the panel according to the commands and data received by the integrated controller.

2. System Interface. This module has a 4-bit and an 8-bit interface to connect with microcontrollers/processors. Some LCD modules also have a built-in serial interface (I2C) for communication with a controller. The selection of interface (4-bit or 8-bit) is determined by the DL bit of the Instruction Register (IR).

3. Data Register (DR). Data Register is an internal register that stores data received by the microcontroller via the system interface. The value populated in the data register is compared with character patterns in Character Generator ROM (CGROM) to generate different standard characters.

4. Instruction Register (IR). Instruction Register is an internal register that stores instructions received by the microcontroller via the system interface.

5. Character Generator ROM (CGROM). It’s an internal Read-Only Memory (ROM) on the LCD module where the patterns for the standard characters are stored. For example, a 16×2 LCD module, CGROM has 5×8 dots, 204 character patterns, and 5×10 dots of 32 characters pattern that are stored. So, the patterns for the 204 characters are permanently stored in the CGROM.

6. Character Generator RAM (CGRAM). The user-defined characters can also be displayed on a character LCD. The patterns for custom characters are stored in CGRAM. On the 16×2 LCD, 5 characters of the 5×8 pixels can be defined by a user program. The user needs to write the font data (which is the character pattern defining what pixels/dots must ON and which must OFF to properly display the character) to generate these characters.

7. Display Data RAM (DDRAM). The data sent to the LCD module by the microcontroller remains stored in DDRAM. In 16×2 character LCD, DDRAM can store a maximum of 80 8-bit characters where the maximum of 40 characters for each row can be stored.

8. Address Counter (AC). The Address Counter is an internal register that stores DDRAM/CGRAM addresses that are transferred by the Instruction register. The AC reads the DDRAM/CGRAM addresses from bits DB0-DB6 of the instruction register. After writing into the DDRAM/CGRAM, the AC is automatically increased by one, while after reading from the DDRAM/CGRAM, the AC is automatically decreased by one.

9. Busy Flag (BF). The bit DB7 of the instruction register is a busy flag of the LCD module. When the LCD is performing some internal operations, this flag is set (HIGH). During this time, the instruction register does not accept any new instruction via the system interface from the microcontroller. New instructions can be written to the IR but only when the busy flag is clear (LOW).

10. Cursor/Blink Control Circuit. This controls the ON/OFF status of the cursor/blink at the cursor position. The cursor appears at the DDRAM address currently set in the AC. For example, if the AC is set to 07H, then the cursor is displayed at the DDRAM address 07H.

11. LCD Driver. It controls the LCD panel and the display. In the 16×2 character LCD, the LCD driver circuit consists of 16 common signal drivers and 40 segment signal drivers.

12. Timing Generation Circuit. It generates the timing signals for the operation of internal circuits, such as the DDRAM, CGRAM, and CGROM. The timing signals for reading RAM (DDRAM/CGRAM) module are generated separately to display characters and timing signals for the internal operations of the integrated controller/processor of LCD. This is so that the display does not interfere with the internal operations of the integrated controller of the LCD module.

Interfacing character LCDsMost of the character LCDs have a 14-pin or 16-pin system interface for communication with a microcontroller/processor. The 16-pin system interface is the most common.

To interface the LCD module with a microcontroller or Arduino, the digital I/O pins of the microcontroller must be connected with the RS, RW, EN, and data pins DB0 to DB7.

In 4-bit mode, two pulses are required at the EN pin to write data/instruction to the LCD. At first, the higher nibble of data or the instruction is latched. Then, in the second pulse lower nibble of the data/instruction is transferred.

In an 8-bit mode, the entire 8-bit data/instruction is written to the LCD in a single pulse at the EN pin. So, the 4-bit mode saves the microcontroller pins but has a slight latency in comparison to the 8-bit mode of operation. The 8-bit mode suffers less from latency but engages 4 extra pins from the microcontroller.

It’s also possible to interface the LCD module with Arduino using a serial-to-parallel converter. Then, only two pins of Arduino are required to interface with the LCD module.

The ground pin of the LCD module (pin 1) must be connected to the ground while the VCC pin (pin 2) must be connected to the supply voltage. The 3.3 or 5V pin of Arduino can be used to supply voltage to the LCD module. The VEE pin must be connected to the variable terminal of a variable resistor, and the fixed terminals of the variable resistor must be connected to the VCC and ground.

How character LCD worksIt is possible to read/write data with the LCD module. To write data/instructions to the LCD module, the RW pin must be clear. Then, if the RS is set, an 8-bit data sent by the microcontroller stores in the data register (DR) of the LCD module. This 8-bit data sent by the microcontroller will store in the instruction register (IR) of the LCD module.

When data is sent to the LCD module (RW=0, RS=1, EN=1->0), it is written in the DDRAM and the Address Counter of the LCD is increased by one. The LCD controller compares the 8-bit data with the CGROM addresses and displays the appropriate character on the LCD at the associated DDRAM address. This serves as the instruction to show that the display has been received.

When the instruction is sent to the LCD module (RW=0, RS=0, EN=1->0), it is stored in the instruction register and according to the pre-defined instruction set of the LCD controller, the appropriate operation is executed on the display (to set display ON, set display OFF, set cursor ON, set cursor OFF, clear DDRAM, etc.).

Sometimes, the microcontroller may need to read data from the LCD. A microcontroller can read content from the instruction register, DDRAM, and CGRAM of the LCD. To read data from the LCD, the RW pin must be set. When the RW is set and the RS is clear, the microcontroller reads the content of Instruction Register (IR) — including the busy flag (DB7 of IR) and address counter (DB6 to DB0 of IR) — when applying a HIGH to LOW pulse at EN pin.

When the RW is set and the RS is set, the microcontroller reads the content of the DDRAM or CGRAM according to the current value of the address counter when applying a HIGH to LOW pulse at EN pin.

If the LCD module is interfaced to typical microcontrollers (8051, PIC, AVR, etc.), the RS, RW, EN, and the data bits need to be set individually to perform the read/write operations.

Arduino has a Liquid Crystal library (LiquidCrystal.h) available that makes programming LCD with Arduino extremely easy. This library can be imported by the following statement:

LiquidCrystal() methodThis method is used to create a Liquid Crystal object. The object must be created according to the circuit connections of the LCD module when using Arduino.

The object takes the pin numbers of the Arduino as arguments. The pin numbers where the RS, RW, EN, and the data pins (DB7-DB0 for 8-bit mode and DB7-DB4 for 4-bit mode) of the LCD are connected, has to be passed as arguments in the object definition.

This method is used to initialize the LCD module. The function takes the size of the LCD (expressed by number of columns and rows in the LCD) as the arguments.

This method positions the cursor at the given location on the LCD panel. It takes the column and row as the argument where the cursor has to be placed and a subsequent character has to be displayed.

This method is used to print text to the LCD. It takes a string argument, which has to be displayed at the current cursor position on the LCD. It can take base of the value passed as an optional argument — if only printing numbers.

How to check the LCDA common concern when interfacing the LCD module is to identify whether or not the LCD module is, indeed, working. When connecting the LCD with Arduino (or any other MCU), if only the lower line of the LCD brightens, then the LCD module is working.

Sometimes when you try to print on the LCD, nothing occurs, except the lower line of the LCD illuminating. In this case, the possible reasons can be one of the following:

2. The LCD module might have been interfaced in the reverse pin order (i.e. instead of pins 1 to 16, circuit connections might have been made from pins 16 to 1 of the LCD module).

4. The contrast of the LCD at the VEE pin might not have been adjusted properly. If the adjustment of contrast does not work, try connecting the VEE pin directly to the ground, so that the LCD module is adjusted to maximum contrast.

5. If after checking all the circuit connections, LCD panel still does not display text, check if the code uploaded to Arduino is correct or not. For example, it is possible that if the LCD display is not cleared after initialization, garbage values may display on the LCD instead of the intended text.

Components required1. Arduino UNO x12. 16×2 character LCD x13. 10K Pot x14. 330 Ohms Resistor or any low-value resistor x15. Breadboard x16. Male-to-Male Jumper Wires or Connecting Wires

Circuit connectionsThe LCD module used in this project is JHD162A. This is a 16×2 LCD module with 5×8 character dots. The LCD module has a 16-pin interface. The LCD is interfaced with Arduino in 4-bit mode.

Pin 1 (GND) and 16 (LED) of the LCD module are connected to ground while pin 2 (VCC) is connected to the VCC. The pin 15 (LED+) from the LCD module is, once again, connected to the VCC via a small-value resistor. The pin 3 (VEE) is connected to the variable terminal of a pot while the fixed terminals of the pot are connected to the ground and VCC.

The R/W pin is connected to the ground as Arduino will only write data to the LCD module. The RS, EN, DB4, DB5, DB6, and DB7 pins of the LCD are connected to pins 13, 11, 7, 6, 5, and 4 of Arduino UNO, respectively. The breadboard supplies the common ground. The 5V supplies the rail from one of the ground pins and 5V pin of the Arduino UNO, respectively.

The LCD module is connected with Arduino in a 4-bit mode. First, the LCD is initialized and the display is cleared to get rid of any garbage values in the DDRAM. The cursor is set to column 1 of the line 0, and the text, “EEWORLDONLINE” is printed on LCD.

Next, the cursor is moved to column 0 of line 1 and text, “EngineersGarage” is printed on the LCD. A delay of 750 milliseconds is given and the LCD is cleared again.

The cursor is moved to column 0 of the line 0 and the text, “EngineersGarage” is printed on the LCD. The cursor is then moved to column 1 of line 1 and text, “EEWORLDONLINE” is printed on the LCD.

Programming guideThe LiquidCrystal.h library is imported in the code. Then, an object defined by the variable “lcd” is defined for the LiquidCrystal class.

In the loop() function, the LCD display is cleared using the clear() method and he cursor is set at column 1 of line 0 by using the setCursor() method. The text “EEWORLDONLINE” is printed using the print() method on the “lcd” object. Similarly, the text “EngineersGarage” is printed at column 0 of line 1. A delay of 750 milliseconds is given by using the delay() function.

The body of the loop() function will keep repeating itself until Arduino is shutdown. Therefore, both texts keep displaying on the LCD module, alternating their position between line 0 and 1 of the panel.

If you’ve ever tried to connect an LCD display to an Arduino, you might have noticed that it consumes a lot of pins on the Arduino. Even in 4-bit mode, the Arduino still requires a total of seven connections – which is half of the Arduino’s available digital I/O pins.

The solution is to use an I2C LCD display. It consumes only two I/O pins that are not even part of the set of digital I/O pins and can be shared with other I2C devices as well.

True to their name, these LCDs are ideal for displaying only text/characters. A 16×2 character LCD, for example, has an LED backlight and can display 32 ASCII characters in two rows of 16 characters each.

If you look closely you can see tiny rectangles for each character on the display and the pixels that make up a character. Each of these rectangles is a grid of 5×8 pixels.

At the heart of the adapter is an 8-bit I/O expander chip – PCF8574. This chip converts the I2C data from an Arduino into the parallel data required for an LCD display.

In addition, there is a jumper on the board that supplies power to the backlight. To control the intensity of the backlight, you can remove the jumper and apply external voltage to the header pin that is marked ‘LED’.

If you are using multiple devices on the same I2C bus, you may need to set a different I2C address for the LCD adapter so that it does not conflict with another I2C device.

An important point here is that several companies manufacture the same PCF8574 chip, Texas Instruments and NXP Semiconductors, to name a few. And the I2C address of your LCD depends on the chip manufacturer.

According to the Texas Instruments’ datasheet, the three address selection bits (A0, A1 and A2) are placed at the end of the 7-bit I2C address register.

By shorting the solder jumpers, the address inputs are puled LOW. If you were to short all three jumpers, the address would be 0x20. The range of all possible addresses spans from 0x20 to 0x27. Please see the illustration below.

According to the NXP Semiconductors’ datasheet, the three address selection bits (A0, A1 and A2) are also placed at the end of the 7-bit I2C address register. But the other bits in the address register are different.

By shorting the solder jumpers, the address inputs are puled LOW. If you were to short all three jumpers, the address would be 0x38. The range of all possible addresses spans from 0x38 to 0x3F. Please see the illustration below.

So your LCD probably has a default I2C address 0x27Hex or 0x3FHex. However it is recommended that you find out the actual I2C address of the LCD before using it.

Connecting an I2C LCD is much easier than connecting a standard LCD. You only need to connect 4 pins instead of 12. Start by connecting the VCC pin to the 5V output on the Arduino and GND to ground.

Now we are left with the pins which are used for I2C communication. Note that each Arduino board has different I2C pins that must be connected accordingly. On Arduino boards with the R3 layout, the SDA (data line) and SCL (clock line) are on the pin headers close to the AREF pin. They are also known as A5 (SCL) and A4 (SDA).

After wiring up the LCD you’ll need to adjust the contrast of the display. On the I2C module you will find a potentiometer that you can rotate with a small screwdriver.

Plug in the Arduino’s USB connector to power the LCD. You will see the backlight lit up. Now as you turn the knob on the potentiometer, you will start to see the first row of rectangles. If that happens, Congratulations! Your LCD is working fine.

To drive an I2C LCD you must first install a library called LiquidCrystal_I2C. This library is an enhanced version of the LiquidCrystal library that comes with your Arduino IDE.

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

The I2C address of your LCD depends on the manufacturer, as mentioned earlier. If your LCD has a Texas Instruments’ PCF8574 chip, its default I2C address is 0x27Hex. If your LCD has NXP Semiconductors’ PCF8574 chip, its default I2C address is 0x3FHex.

So your LCD probably has I2C address 0x27Hex or 0x3FHex. However it is recommended that you find out the actual I2C address of the LCD before using it. Luckily there’s an easy way to do this, thanks to the Nick Gammon.

But, before you proceed to upload the sketch, you need to make a small change to make it work for you. You must pass the I2C address of your LCD and the dimensions of the display to the constructor of the LiquidCrystal_I2C class. If you are using a 16×2 character LCD, pass the 16 and 2; If you’re using a 20×4 LCD, pass 20 and 4. You got the point!

First of all an object of LiquidCrystal_I2C class is created. This object takes three parameters LiquidCrystal_I2C(address, columns, rows). This is where you need to enter the address you found earlier, and the dimensions of the display.

In ‘setup’ we call three functions. The first function is init(). It initializes the LCD object. The second function is clear(). This clears the LCD screen and moves the cursor to the top left corner. And third, the backlight() function turns on the LCD backlight.

After that we set the cursor position to the third column of the first row by calling the function lcd.setCursor(2, 0). The cursor position specifies the location where you want the new text to be displayed on the LCD. The upper left corner is assumed to be col=0, row=0.

There are some useful functions you can use with LiquidCrystal_I2C objects. Some of them are listed below:lcd.home() function is used to position the cursor in the upper-left of the LCD without clearing the display.

lcd.scrollDisplayRight() function scrolls the contents of the display one space to the right. If you want the text to scroll continuously, you have to use this function inside a for loop.

lcd.scrollDisplayLeft() function scrolls the contents of the display one space to the left. Similar to above function, use this inside a for loop for continuous scrolling.

If you find the characters on the display dull and boring, you can create your own custom characters (glyphs) and symbols for your LCD. They are extremely useful when you want to display a character that is not part of the standard ASCII character set.

As discussed earlier in this tutorial a character is made up of a 5×8 pixel matrix, so you need to define your custom character within that matrix. You can use the createChar() function to define a character.

To use createChar() you first set up an array of 8 bytes. Each byte in the array represents a row of characters in a 5×8 matrix. Whereas, 0 and 1 in a byte indicate which pixel in the row should be ON and which should be OFF.

CGROM is used to store all permanent fonts that are displayed using their ASCII codes. For example, if we send 0x41 to the LCD, the letter ‘A’ will be printed on the display.

CGRAM is another memory used to store user defined characters. This RAM is limited to 64 bytes. For a 5×8 pixel based LCD, only 8 user-defined characters can be stored in CGRAM. And for 5×10 pixel based LCD only 4 user-defined characters can be stored.

Creating custom characters has never been easier! We have created a small application called Custom Character Generator. Can you see the blue grid below? You can click on any 5×8 pixel to set/clear that particular pixel. And as you click, the code for the character is generated next to the grid. This code can be used directly in your Arduino sketch.

Your imagination is limitless. The only limitation is that the LiquidCrystal library only supports eight custom characters. But don’t be discouraged, look at the bright side, at least we have eight characters.

After the library is included and the LCD object is created, custom character arrays are defined. The array consists of 8 bytes, each byte representing a row of a 5×8 LED matrix. In this sketch, eight custom characters have been created.

Let’s examine the Heart[8] array as an example. You can see how the bits (0s and 1s) are forming a heart shape. 0 turns the pixel off and 1 turns the pixel on.

In setup, a custom character is created using the createChar() function. This function takes two parameters. The first parameter is a number between 0 and 7 to reserve one of the 8 supported custom characters. The second is the name of the array.

In this digital age, we come across LCDs all around us from simple calculators to smartphones, computers and television sets, etc. The LCDs use liquid crystals to produce images or texts and are divided into different categories based on different criteria like type of manufacturing, monochrome or colour, and weather Graphical or character LCD. In this tutorial, we will be talking about the 16X2 character LCD Modules.

The 16x2 LCDs are very popular among the DIY community. Not only that, but you can also find them in many laboratory and industrial equipment. It can display up to 32 characters at a time. Each character segment is made up of 40 pixels that are arranged in a 5x8 matrix. We can create alphanumeric characters and custom characters by activating the corresponding pixels. Here is a vector representation of a 16x2 LCD, in which you can see those individual pixels.

As the name indicates, these character segments are arranged in 2 lines with 16 characters on each line. Even though there are LCDs with different controllers are available, The most widely used ones are based on the famous HD44780 parallel interface LCD controller from Hitachi.

The 16x2 has a 16-pin connector. The module can be used either in 4-bit mode or in 8-bit mode. In 4-bit mode, 4 of the data pins are not used and in 8-bit mode, all the pins are used. And the connections are as follows:

Vo / VEE Contrast adjustment; the best way is to use a variable resistor such as a potentiometer. The output of the potentiometer is connected to this pin. Rotate the potentiometer knob forward and backwards to adjust the LCD contrast.

EnableSends data to data pins when a high to low pulse is given; Extra voltage push is required to execute the instruction and EN (enable) signal is used for this purpose. Usually, we set en=0, when we want to execute the instruction, we make it high en=1 for some milliseconds. After this we again make it ground that is, en=0.

The 16x2 LCD modules are popular among the DIY community since they are cheap, easy to use and most importantly enable us to provide information very efficiently. With just 6 pins, we can display a lot of data on the display.

The module has 16 pins. Out of these 16 pins, two pins are for power, two pins are for backlight, and the remaining twelve pins are for controlling the LCD.

If you look at the backside of the module you can simply see that there are not many components. The main components are the two controller chips that are under the encapsulation. There is an onboard current limiting resistor for the backlight. This may vary from different modules from different manufacturers. The only remaining components are a few complimentary resistors for the LCD controller.

In the module PCB, you may have noticed some unpopulated footprints. These footprints are meant for charge pump circuits based on switched capacitor voltage converters like ICL7660 or MAX660. You can modify your LCD to work with 3.3V by populating this IC and two 10uF capacitors to C1 and C2 footprint, removing Jumper J1 and adding jumper J3. This modification will generate a negative contrast voltage of around 2.5V. This will enable us to use the LCD even with a VCC voltage of 3.3V.

Another issue to be concerned about is the oscillator frequency, i.e. when the supply voltage is reduced, the built-in clock frequency will also get reduced. The Rosc should be changed to a suitable value if any timing issues or command execution issues occur. The typical value of the Rosc for 5V VCC is 91KOhms.

To test whether a 16x2 LCD works or not, connect the VDD, GND and backlight pins to 5v and GND. Connect the centre terminal of a 10K variable resistor to the VEE pin. Connect the other two terminals to VCC and GND. Simply rotate the variable resistor you will see that the contrast will be adjusted and small blocks are visible. If these rectangles are visible, and you were able to adjust the contrast, then the LCD is working

There are 16 pins on the display module. Two of them are for power (VCC, GND), one for adjusting the contrast (VEE), three are control lines (RS, EN, R/W), eight pins are data lines(D0-D7) and the last two pins are for the backlight (A, K).

The 16x2 LCD has 32 character areas, which are made up of a 5x8 matrix of pixels. By turning on or off these pixels we can create different characters. We can display up to 32 characters in two rows.

Yes, we can. We can store up to eight custom characters in the CGRAM (64 bytes in size) area. We can create load the matrix data for these characters and can recall when they need to be displayed.

Controlling the LCD module is pretty simple. Let’s walk through those steps. To adjust the contrast of the LCD, the Vo/ VEE pin is connected to a variable resistor. By adjusting the variable resistor, we can change the LCD contrast.

The RS or registry select pin helps the LCD controller to know whether the incoming signal is a control signal or a data signal. When this pin is high, the controller will treat the signal as a command instruction and if it’s low, it will be treated as data. The R/W or Read/Write pin is used either to write data to the LCD or to read data from the LCD. When it’s low, the LCD module will be in write mode and when it’s high, the module will be in reading mode.

The Enable pin is used to control the LCD data execution. By default, this pin is pulled low. To execute a command or data which is provided to the LCD data line, we will just pull the Enable pin to high for a few milliseconds.

To test the LCD module, connect the VDD, GND, and backlight pins to 5v and GND. Connect the center terminal of a 10K variable resistor to the VEE pin. Connect the other two terminals to VCC and GND as per the below connection diagram-

Simply rotate the