lcd module commands in stock

We come across Liquid Crystal Display (LCD) displays everywhere around us. Computers, calculators, television sets, mobile phones, and digital watches use some kind of display to display the time.

An LCD screen is an electronic display module that uses liquid crystal to produce a visible image. The 16×2 LCD display is a very basic module commonly used in DIYs and circuits. The 16×2 translates a display of 16 characters per line in 2 such lines. In this LCD, each character is displayed in a 5×7 pixel matrix.

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 backward to adjust the LCD contrast.

A 16X2 LCD has two registers, namely, command and data. The register select is used to switch from one register to other. RS=0 for the command register, whereas RS=1 for the data register.

Command Register: The command register stores the command instructions given to the LCD. A command is an instruction given to an LCD to do a predefined task. Examples like:

Data Register: The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD. When we send data to LCD, it goes to the data register and is processed there. When RS=1, the data register is selected.

Generating custom characters on LCD is not very hard. It requires knowledge about the custom-generated random access memory (CG-RAM) of the LCD and the LCD chip controller. Most LCDs contain a Hitachi HD4478 controller.

CG-RAM address starts from 0x40 (Hexadecimal) or 64 in decimal. We can generate custom characters at these addresses. Once we generate our characters at these addresses, we can print them by just sending commands to the LCD. Character addresses and printing commands are below.

LCD modules are very important in many Arduino-based embedded system designs to improve the user interface of the system. Interfacing with Arduino gives the programmer more freedom to customize the code easily. Any cost-effective Arduino board, a 16X2 character LCD display, jumper wires, and a breadboard are sufficient enough to build the circuit. The interfacing of Arduino to LCD display is below.

The combination of an LCD and Arduino yields several projects, the most simple one being LCD to display the LED brightness. All we need for this circuit is an LCD, Arduino, breadboard, a resistor, potentiometer, LED, and some jumper cables. The circuit connections are below.

16×2 LCD is named so because; it has 16 Columns and 2 Rows. There are a lot of combinations available like, 8×1, 8×2, 10×2, 16×1, etc. But the most used one is the 16*2 LCD, hence we are using it here.

All the above mentioned LCD display will have 16 Pins and the programming approach is also the same and hence the choice is left to you. Below is the Pinout and Pin Description of 16x2 LCD Module:

These black circles consist of an interface IC and its associated components to help us use this LCD with the MCU. Because our LCD is a 16*2 Dot matrix LCD and so it will have (16*2=32) 32 characters in total and each character will be made of 5*8 Pixel Dots.  A Single character with all its Pixels enabled is shown in the below picture.

So Now, we know that each character has (5*8=40) 40 Pixels and for 32 Characters we will have (32*40) 1280 Pixels. Further, the LCD should also be instructed about the Position of the Pixels.

It will be a hectic task to handle everything with the help of MCU, hence an Interface IC like HD44780 is used, which is mounted on LCD Module itself. The function of this IC is to get the Commands and Data from the MCU and process them to display meaningful information onto our LCD Screen.

The LCD can work in two different modes, namely the 4-bit mode and the 8-bit mode. In 4 bit mode we send the data nibble by nibble, first upper nibble and then lower nibble. For those of you who don’t know what a nibble is: a nibble is a group of four bits, so the lower four bits (D0-D3) of a byte form the lower nibble while the upper four bits (D4-D7) of a byte form the higher nibble. This enables us to send 8 bit data.

As said, the LCD itself consists of an Interface IC. The MCU can either read or write to this interface IC. Most of the times we will be just writing to the IC, since reading will make it more complex and such scenarios are very rare. Information like position of cursor, status completion interrupts etc. can be read if required, but it is out of the scope of this tutorial.

The Interface IC present in most of the LCD is HD44780U,in order to program our LCD we should learn the complete datasheet of the IC. The datasheet is given here.

There are some preset commands instructions in LCD, which we need to send to LCD through some microcontroller. Some important command instructions are given below:

Above figure shows that each LCD have its own pixel rows and columns like 1×16 has single raw and sixteen columns i.e. 16 pixel and each pixel size is of 5×8 as shown but we can see only 5×7 cause last raw is used by cursor.

The Serial Monitor is a convenient way to view data from an Arduino, but what if you want to make your project portable and view sensor values without access to a computer? Liquid crystal displays (LCDs) are excellent for displaying a string of words or sensor data.

This guide will help you in getting your 16×2 character LCD up and running, as well as other character LCDs (such as 16×4, 16×1, 20×4, etc.) that use Hitachi’s LCD controller chip, the HD44780.

As the name suggests, these LCDs are ideal for displaying only characters. A 16×2 character LCD, for example, can display 32 ASCII characters across two rows.

Character LCDs are available in a variety of sizes and colors, including 16×1, 16×4, 20×4, white text on a blue background, black text on a green background, and many more.

One advantage of using any of these displays in your project is that they are “swappable,” meaning that you can easily replace them with another LCD of a different size or color. Your code will need to be tweaked slightly, but the wiring will remain the same!

Before we get into the hookup and example code, let’s check out the pinout. A standard character LCD has 16 pins (except for an RGB LCD, which has 18 pins).

Vo (LCD Contrast) pin controls the contrast of the LCD. Using a simple voltage divider network and a potentiometer, we can make precise contrast adjustments.

RS (Register Select) pin is used to separate the commands (such as setting the cursor to a specific location, clearing the screen, etc.) from the data. The RS pin is set to LOW when sending commands to the LCD and HIGH when sending data.

R/W (Read/Write) pin allows you to read data from or write data to the LCD. Since the LCD is only used as an output device, this pin is typically held low. This forces the LCD into WRITE mode.

E (Enable) pin is used to enable the display. When this pin is set to LOW, the LCD ignores activity on the R/W, RS, and data bus lines; when it is set to HIGH, the LCD processes the incoming data.

The LCD has two separate power connections: one for the LCD (pins 1 and 2) and one for the LCD backlight (pins 15 and 16). Connect LCD pins 1 and 16 to GND and 2 and 15 to 5V.

Depending on the manufacturer, some LCDs include a current-limiting resistor for the backlight. It is located on the back of the LCD, close to pin 15. If your LCD does not contain this resistor or if you are unsure whether it does, you must add one between 5V and pin 15. It should be safe to use a 220 ohm resistor, although a value this high may make the backlight slightly dim. For better results, check the datasheet for the maximum backlight current and choose an appropriate resistor value.

Let’s connect a potentiometer to the display. This is necessary to fine-tune the contrast of the display for best visibility. Connect one side of the 10K potentiometer to 5V and the other to Ground, and connect the middle of the pot (wiper) to LCD pin 3.

That’s all. Now, turn on the Arduino. You will see the backlight light up. As you turn the potentiometer knob, you will see the first row of rectangles appear. If you have made it this far, Congratulations! Your LCD is functioning properly.

We know that data is sent to the LCD via eight data pins. However, HD44780-based LCDs are designed so that we can communicate with them using only four data pins (in 4-bit mode) rather than eight (in 8-bit mode). This helps us save 4 I/O pins!

The sketch begins by including the LiquidCrystal library. This library comes with the Arduino IDE and allows you to control Hitachi HD44780 driver-based LCD displays.

Next, an object of the LiquidCrystal class is created by passing as parameters the pin numbers to which the LCD’s RS, EN, and four data pins are connected.

In the setup, two functions are called. The first function is begin(). It is used to initialize the interface to the LCD screen and to specify the dimensions (columns and rows) of the display. If you’re using a 16×2 character LCD, you should pass 16 and 2; if you’re using a 20×4 LCD, you should pass 20 and 4.

In the loop, the print() function is used to print “Hello world!” to the LCD. Please remember to use quotation marks " " around the text. There is no need for quotation marks when printing numbers or variables.

The function setCursor() is then called to move the cursor to the second row. The cursor position specifies where you want the new text to appear on the LCD. It is assumed that the upper left corner is col=0 and row=0.

There are many useful functions you can use with LiquidCrystal Object. Some of them are listed below:lcd.home() function positions 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 the above function, use this inside a for loop for continuous scrolling.

lcd.display() function turns on the LCD display, after it’s been turned off with noDisplay(). This will restore the text (and cursor) that was on the display.

The CGROM stores the font that appears on a character LCD. When you instruct a character LCD to display the letter ‘A’, it needs to know which dots to turn on so that we see an ‘A’. This data is stored in the CGROM.

CGRAM is an additional memory for storing user-defined characters. This RAM is limited to 64 bytes. Therefore, for a 5×8 pixel LCD, only 8 user-defined characters can be stored in CGRAM, whereas for a 5×10 pixel LCD, only 4 can be stored.

After including the library and creating the LCD object, custom character arrays are defined. The array consists of 8 bytes, with each byte representing a row in a 5×8 matrix.

The lcd_data_write_nibble would be identical to lcd_cmd_write_nibble except that we would insert ORI r24, 0x04 after the line with the ANDI instruction in order to set the RS flag.

The next important project after Blinking LEDs with any microcontroller is to display characters on a LCD. In this project, we will see how to interface a LCD with LPC2148 Microcontroller and when we say LCD, a 16 X 2 Alphanumeric LCD module to be specific.

Before going to the actual project, we will discuss a few things about 16 x 2 LCD display. A LCD display or liquid crystal display is a display module with liquid crystals and backlight by LEDs. A 16 x 2 LCD display consists of two rows of display with each row consisting of 16 characters.

The most common type of 16 x 2 LCD display available in the market is JHD162A with either HD44780 or KS0066U Display Controller. HD44780 is manufactured by Hitachi and KS0066U is manufactured by Samsung. Both the controllers are compatible with each other.

From the pin configuration, it is clear that the pins can be sorted according to Power pins, control pins and data pins. Power pins i.e. pins 1, 2, 3, 15 and 16 are used to supply for the module as well as the backlight LEDs. The voltage to the Contract Adjust Pin (Pin 3 or VEE) is usually given from a Potentiometer and will control the contrast of the actual display when the POT is adjusted.

There are 8 data pins for transmitting 8 – bits of data i.e. 1 byte of data at a time. The LCD can be used in either 8 – bit mode or 4 – bit mode. In 4 – bit mode, only 4 of the 8 data lines will be utilized for transmitting the data.

The Enable (E) pin, as the name indicates, is used to enable the execution of the data or instructions. The data or instruction are executed by the LCD module only when a HIGH to LOW pulse is given to the Enable pin i.e. only on the falling edge of a pulse.

From the circuit diagram, the four data pins of the LCD (D4 – D7) are connected to P0.17 to P0.20 pins of the LPC2148. The control pins RS and E are connected to P0.12 and P.13 pins of the LPC2148 MCU.

It is clear from the circuit diagram that the LCD is used in 4 – bit mode. The advantage of using 4 – bit mode in LCD is it requires only 4 pins from the microcontroller, which is very important in resource intensive applications.

There is also a tradeoff of using the 4 – bit mode in LCD. Since only 4 – pins are used, we can send only 4 – bits of data at a time. Hence, in order to send a byte of data, the time will be taken will double that of an 8 – bit mode.

Important Note: The ARM7 MCUs and in particular the LPC2148 MCU works on a 3.3V supply. The ARM7 development board used in the project has a separate 5V supply for the LCD module and doesn’t draw any power from the MCU.

While interfacing the 5V LCD module with a 3.3V MCU like a LPC2148, there is a chance that the connection might work if connected directly. In this case, we need to use a Level Shifter IC as an intermediate module between the MCU i.e. LPC2148 and the LCD Module.

After connecting the LCD module as per the circuit diagram, the first step is to initialize the LCD module. For that, we need to use some of the commands for the LCD in our program. The following table shows a list of commands used for configuring the LCD Module and also their respective functions.

The above table seems confusing and is difficult to understand. Hence, the following table will give you a simplified list of LCD commands and their respective functions.

As we have seen in the previous tutorial how to setup the PLL so that the CPU clock is running at 60 MHz (maximum for LPC2148), we will include that in this code as well. The steps for writing the programming the LCD interface with LPC2148 will be as follows.

/* Function definition of cmd function. It is used to send initializing commands to the LCD module. Hence, the RS pin is set to LOW. Also the code is written two times: once the 4 bits are received, they are shifted and the next 4 bits are captured*/

This serial LCD kit includes a 16x2 LCD together with a small "serial interface" PCB fitted with a PICAXE-18M2 chip. The on-board PICAXE-18M2 chip is provided pre-programmed with the open-source AXE133 firmware, which allows this on-board 18M2 chip to act as a "slave" serial driver for the LCD display. This allows your main project to display text on the serial LCD via simple serout commands, such as

The control codes are identical to our popular AXE033 module, so this kit can be used as an altenate to the AXE033. On this board the slave chip is a completely normal 18M2, so it can also be reprogrammed whenever you want (e.g. to change the power-up welcome message or even temporarily "borrowed" for another project!). Click on the resources tab above to download the AXE133 BASIC firmware file.

Displaying Text on 16×1, 16×2 or any size of character lcd is not a complex task. Once you know about the internal structure of the character lcd, lcd pin out, registers associated with lcd’s and CG-RAM(Character Generated RAM) then its all on your finger tips. If you are really interested in lcd programming, and want to know about how to display text on lcd? First take a small tutorial on the Internal Structure of character 16×2 Lcd. Because if you don’t know about internal structure of lcd you will be unable to fully understand the sequence of steps taken to display text on Lcd given below.

Character lcd can perform both read and write functions. Normally lcds are only used to write text on them. Read operation is performed in few nominal tasks. Below are some steps to display text on lcd. I am going to display Character ‘A’ on lcd.

First select the operation which you want to perform ‘Read’ or ‘Write’. Making R/W Pin of Lcd 0(R/W=0) will select the write operation. Now lcd is set in write mode and you can write any text to lcd. If R/W=1 lcd is set in Read mode and you can read data from lcd. Since i want to display ‘A‘ on lcd. I made R/W=0.

2. Their are two registers in lcddata and command. To display text on lcd you have to select data register of lcd. To execute command you have to select command register of lcd. To select data register make RS=1. To switch to command register make Rs=0. In our case we are displaying text on lcd so make RS=1.

3. Place your text on data pins of Lcd. Since lcd’s data pins are 8-bit wide so place data that is 8-bit wide. Since we want to display ‘A‘ on lcd. ASCII value of ‘A‘ is 65(decimal), 01000001(Binary), 0x41 (Hexadecimal). Place this value on lcd data pins.

To display next character repeat the above steps again.To make lcd fully functional you first have to initialize lcd. By initialization i mean set the font of character, decide the cursor(Blinking or not blinking) select the position where you want to display character etc. These parameters are set by sending commands to lcd. Standard lcd commands and their functions are given in the link below.

Note: To execute commands steps are same like to display text only difference is in the RS pin selection. To execute commands you have to select the command register of lcd. Make RS=0 to select command register of lcd. Now your commands goes to command register and you can execute them by make en=1 and back to en=0.

In this project i will display my name “USMAN ALI BUTT” on both rows of 16×2 lcd. First my name will appear on first row of 16×2 lcd. Then after some time it disappears and re appears on second line of 16×2 lcd. The project is really simple.

The circuit for the project is simple. Connect Port-1 of your 8051(89c51,89c52) microcontroller to 8 data pins of the lcd. The pins should interface the microcontroller in the order that pin#1 of Port-1 is connected to pin#1 of data pin on lcd. Pin#2 of Port-1 of 8051 to pin#2 of lcd and so on up till pin 8. Connect pin#5 of Port-3 to rs(register select) pin of lcd. pin#7 of microcontroller Port-3 to rw(read write) pin of lcd and pin#6 of microcontroller Port-3 to en(enable) pin of lcd.​

More Projects related to displaying Text On 16×2 lcd are given below. Each project is made using different type of microcontroller, arduino pic microcontroller etc. Projects are open source. You can use and edit code according to your need.

Lcd stands for liquid crystal display. Character and graphical lcd’s are most common among hobbyist and diy electronic circuit/project makers. Since their interface serial/parallel pins are defined so its easy to interface them with many microcontrollers. Many products we see in our daily life have lcd’s with them. They are used to show status of the product or provide interface for inputting or selecting some process. Washing machine, microwave,air conditioners and mat cleaners are few examples of products that have character or graphical lcd’s installed in them. In this tutorial i am going to discuss about the character lcd’s. How they work? their pin out and initialization commands etc.

​Character lcd’s come in many sizes 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 .Many multinational companies like Philips, Hitachi, Panasonic make their own custom type of character lcd’s to be used in their products. All character lcd’s performs the same functions(display characters numbers special characters, ascii characters etc).Their programming is also same and they all have same 14 pins (0-13) or 16 pins (0 to 15).​

In an mxn lcd. M denotes number of columns and n represents number of rows. Like if the lcd is denoted by 16×2 it means it has 16 columns and 2 rows. Few examples are given below. 16×2, 8×1 and 8×2 lcd are shown in the picture below. Note the difference in the rows and columns.

On a character lcd a character is generated in a matrix of 5×8 or 5×7. Where 5 represents number of columns and 7/8 represent number of rows. Maximum size of the matrix is 5×8. You can not display character greater then 5×8 dimension matrix. Normally we display a character in 5×7 matrix and left the 8th row for the cursor. If we use the 8th row of the matrix for the character display, then their will be no room for cursor. The picture below shows the 5×8 dot matrix pixels arrangement.

To display character greater than this dimension you have to switch to graphical lcd’s. To learn about graphical lcds here is a good tutorialGraphical Lcd’s Working and Pin out.

The picture above shows the pin out of the character lcd. Almost all the character lcd’s are composed of the same pin out. Lcd’s with total pin count equal to 14 does not have back light control option. They might have back light always on or does not have a back light. 16 total pin count lcd’s have 2 extra A and K pins. A means anode and K cathode, use these pins to control the back light of lcd.

Character Lcd’s have a controller build in to them named HD44780. We actually talk with this controller in order to display character on the lcd screen. HD44780 must be properly handled and initialized before sending any data to it. HD44780 has some registers which are initialized and  manipulated for character displaying on the lcd. These registers are selected by the pins of character lcd.

When we send commands to lcd these commands go to Command register and are processed their.Commands with their full description are given in the picture below.When Rs=0 command register is selected.

When we select the register Rs(Command and Data) and set Rw(read –  write) and placed the raw value on 8-data lines, now its time to execute the instruction. By instruction i mean the 8-bit data or 8-bit command present on Data lines of lcd. For sending the final data/command present on the data lines we use this enable pin.Usually it remains en=0 and when we want to execute the instruction we make it high en=1 for some mills seconds. After this we again make it ground en=0.

To set lcd display sharpness use this pin. Best way is to use variable resistor such as potentiometer a variable current makes the character contrast sharp. Connect the output of the potentiometer to this pin. Rotate the potentiometer knob forward and backward to adjust the lcd contrast.

NOTE: we can not send an integer, float, long, double type data to lcd because lcd is designed to display a character only. Only the characters that are supported by the HD44780 controller. See the HD44780 data sheet to find out what characters can we display on lcd.  The 8 data pins on lcd carries only  Ascii 8-bit code of the character to lcd. How ever we can convert our data in character type array and send one by one our data to lcd. Data can be sent using lcd in 8-bit or 4-bit mode. If 4-bit mode is used, two nibbles of data (First high four bits and then low four bits) are sent to complete a full eight-bit transfer. 8-bit mode is best used when speed is required in an application and at least ten I/O pins are available. 4-bit mode requires a minimum of seven bits. In 4-bit mode, only the top 4 data pins (4-7) are used.

Command 0x30 means we are setting 8-bit mode lcd having 1 line and we are initializing it to be 5×7 character display.Now this 5×7 is some thing which every one should know what it stands for. usually the characters are displayed on lcd in 5×8 matrices form. where 5 is total number of columns and is number of rows.Thus the above 0x30 command initializes the lcd to display character in 5 columns and 7 rows the last row we usually leave for our cursor to move or blink etc.

NOTE:You can send commands in hexadecimal or decimal form which one do you like the result is same because the microcontroller translate the command in 8-bit binary value and sends it to the lcd.

Character Lcd’s can be used in 4-bit and 8-bit mode.Before you send commands and data to your lcd. Lcd must first be initialized. This initialization is very important for lcd that are made by Hitachibecause they use HD44780 driver chip sets. Hd44780 Chip set  first has to be initialized before using it. If you don’t initialize it properly you will see nothing on your lcd.

In 4-bit mode the high nibble is sent first before the low nibble and the En pin is toggled eachtime four bits is sent to the LCD. To initialize in 4-bit mode:

To learn more about the difference between 4-bit and 8-bit character lcd mode and operation with demo example visit the tutorial link given below. Demo examples are very easy to understand and one can make changes easily in the code. Please also give us your feed back on the post.