lcd module can be initialized by manufacturer
To me it seems that for some reason the LCD module is not initialized correctly as after the MCU and LCD have both been powered up I only see one (first) line full of full-dotted characters (0xFF) and second line is blank although the screen should be cleared during initialization and cursor should be visible.
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.
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.
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 is the main component in making custom characters. It stores the custom characters once declared in the code. CG-RAM size is 64 bytes providing the option of creating eight characters at a time. Each character is eight bytes in size.
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.
In this Arduino tutorial we will learn how to connect and use an LCD (Liquid Crystal Display)with Arduino. LCD displays like these are very popular and broadly used in many electronics projects because they are great for displaying simple information, like sensors data, while being very affordable.
You can watch the following video or read the written tutorial below. It includes everything you need to know about using an LCD character display with Arduino, such as, LCD pinout, wiring diagram and several example codes.
An LCD character display is a unique type of display that can only output individual ASCII characters with fixed size. Using these individual characters then we can form a text.
If we take a closer look at the display we can notice that there are small rectangular areas composed of 5×8 pixels grid. Each pixel can light up individually, and so we can generate characters within each grid.
The number of the rectangular areas define the size of the LCD. The most popular LCD is the 16×2 LCD, which has two rows with 16 rectangular areas or characters. Of course, there are other sizes like 16×1, 16×4, 20×4 and so on, but they all work on the same principle. Also, these LCDs can have different background and text color.
It has 16 pins and the first one from left to right is the Groundpin. The second pin is the VCCwhich we connect the 5 volts pin on the Arduino Board. Next is the Vo pin on which we can attach a potentiometer for controlling the contrast of the display.
Next, The RSpin or register select pin is used for selecting whether we will send commands or data to the LCD. For example if the RS pin is set on low state or zero volts, then we are sending commands to the LCD like: set the cursor to a specific location, clear the display, turn off the display and so on. And when RS pin is set on High state or 5 volts we are sending data or characters to the LCD.
Next comes the R/W pin which selects the mode whether we will read or write to the LCD. Here the write mode is obvious and it is used for writing or sending commands and data to the LCD. The read mode is used by the LCD itself when executing the program which we don’t have a need to discuss about it in this tutorial.
After all we don’t have to worry much about how the LCD works, as the Liquid Crystal Library takes care for almost everything. From the Arduino’s official website you can find and see the functions of the library which enable easy use of the LCD. We can use the Library in 4 or 8 bit mode. In this tutorial we will use it in 4 bit mode, or we will just use 4 of the 8 data pins.
We will use just 6 digital input pins from the Arduino Board. The LCD’s registers from D4 to D7 will be connected to Arduino’s digital pins from 4 to 7. The Enable pin will be connected to pin number 2 and the RS pin will be connected to pin number 1. The R/W pin will be connected to Ground and theVo pin will be connected to the potentiometer middle pin.
We can adjust the contrast of the LCD by adjusting the voltage input at the Vo pin. We are using a potentiometer because in that way we can easily fine tune the contrast, by adjusting input voltage from 0 to 5V.
Yes, in case we don’t have a potentiometer, we can still adjust the LCD contrast by using a voltage divider made out of two resistors. Using the voltage divider we need to set the voltage value between 0 and 5V in order to get a good contrast on the display. I found that voltage of around 1V worked worked great for my LCD. I used 1K and 220 ohm resistor to get a good contrast.
There’s also another way of adjusting the LCD contrast, and that’s by supplying a PWM signal from the Arduino to the Vo pin of the LCD. We can connect the Vo pin to any Arduino PWM capable pin, and in the setup section, we can use the following line of code:
It will generate PWM signal at pin D11, with value of 100 out of 255, which translated into voltage from 0 to 5V, it will be around 2V input at the Vo LCD pin.
Here’s a simple code through which we can explain the working principle of the Liquid Crystal library. This is the code of the first example from the video:
First thing we need to do is it insert the Liquid Crystal Library. We can do that like this: Sketch > Include Library > Liquid Crystal. Then we have to create an LC object. The parameters of this object should be the numbers of the Digital Input pins of the Arduino Board respectively to the LCD’s pins as follow: (RS, Enable, D4, D5, D6, D7). In the setup we have to initialize the interface to the LCD and specify the dimensions of the display using the begin()function.
The cursor() function is used for displaying underscore cursor and the noCursor() function for turning off. Using the clear() function we can clear the LCD screen.
In case we have a text with length greater than 16 characters, we can scroll the text using the scrollDisplayLeft() orscrollDisplayRight() function from the LiquidCrystal library.
We can choose whether the text will scroll left or right, using the scrollDisplayLeft() orscrollDisplayRight() functions. With the delay() function we can set the scrolling speed.
The first parameter in this function is a number between 0 and 7, or we have to reserve one of the 8 supported custom characters. The second parameter is the name of the array of bytes.
So, we have covered pretty much everything we need to know about using an LCD with Arduino. These LCD Character displays are really handy for displaying information for many electronics project. In the examples above I used 16×2 LCD, but the same working principle applies for any other size of these character displays.
I hope you enjoyed this tutorial and learned something new. Feel free to ask any question in the comments section below and don’t forget to check out my full collection of 30+ Arduino Projects.
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;
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
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
The code initializes the module, display a string in the module using the functions available in the
In the previous chapter, we discussed how a character LCD is interfaced with a PIC microcontroller in 8-bit mode. A character LCD can be configured in 8 bit or 4-bit mode in which 8 data pins and 4 data pins are used respectively this feature allows efficient use of the digital I/0 pins of the microcontroller. This article explains 4 bit LCD interfacing with PIC Microcontroller.
A 16×2 character liquid crystal display (LCD) module is the most basic electronic display module which is widely used. The module will consist of 2 rows each with 16 columns which can display 16 characters. Several other LCD modules are also available like 20×4 dimension LCD which can display 20 characters per line and 4 such lines would be available. The choice for the module depends on the requirement.
The main advantage of using a character LCD instead of a seven segment display and other multi-segment LEDs is that there is no limitation in displaying special & custom character animations and so on. All character LCDs will have 16 pins among which 8 are data pins through which data or commands are passed into the LCD registers.
The features of a character LCD module make it more suitable as an electronic display than 7 segment displays and other multi-segment display modules. Most importantly the module can be interfaced much easily unlike other modules with no complexity in both hardware and software.The 4-bit mode interfacing of the LCD module enables an efficient method of saving the number of general purposes I/O pins which is a major criterion for an embedded system designer. There is no limitation in characters which can be displayed using the module. The contrast of the module can be adjusted using the VEE pin of the module and LED backlight can be enabled with LED+ and LED- which makes the display more bright.
The RS(Register Select) pin of the LCD module is used to select the specific register. When RS is low, command register is selected and when RS is high, data register is selected. State of R/W pin determines the operation to be performed whether to read or write data.
All instructions to be executed by the LCD are latched into the command register of the LCD. LCD commands include a clear display, the cursor on/off, display shift and so on.
Commands are instructions given to the LCD module to perform a predefined task. The task to be performed is defined by the manufacturer. Some of the LCD commands are listed below.
Hardware setup for interfacing the character LCD in 4-bit mode is by connecting the 4 data lines to the GP I/O pins of the controller. Sending a command or data into an LCD configured in 4-bit mode from 8-bit mode such that data need to be sent a nibble after the another. MSB of the data is sent first followed by LSB.
The LCD can be configured in 4-bit mode by sending appropriate instruction which is called ‘Function set’ to it. The function set is the hexadecimal instruction for the LCD MPU to select the working model of LCD. According to the table in the datasheet of the LCD module, the value of function set to initialize the LCD module in 4-bit mode can be calculated as 0x20.
Since we know that only for data lines will be connected in hardware with the microcontroller port. The data needs to be sent in 4 bits. MSB nibble can be sent in first followed by LSB nibble. For example:
Sending data to a 4 bit LCD follows the same method as done with the command except that the data register needs to be selected instead of the command register by driving the RS line high.
The Arduino family of devices is features rich and offers many capabilities. The ability to interface to external devices readily is very enticing, although the Arduino has a limited number of input/output options. Adding an external display would typically require several of the limited I/O pins. Using an I2C interface, only two connections for an LCD character display are possible with stunning professional results. We offer both a 4 x 20 LCD.
The character LCD is ideal for displaying text and numbers and special characters. LCDs incorporate a small add-on circuit (backpack) mounted on the back of the LCD module. The module features a controller chip handling I2C communications and an adjustable potentiometer for changing the intensity of the LED backlight. An I2C LCD advantage is that wiring is straightforward, requiring only two data pins to control the LCD.
A standard LCD requires over ten connections, which can be a problem if your Arduino does not have many GPIO pins available. If you happen to have an LCD without an I2C interface incorporated into the design, these can be easily
The LCD displays each character through a matrix grid of 5×8 pixels. These pixels can display standard text, numbers, or special characters and can also be programmed to display custom characters easily.
Connecting the Arduino UNO to the I2C interface of the LCD requires only four connections. The connections include two for power and two for data. The chart below shows the connections needed.
The I2C LCD interface is compatible across much of the Arduino family. The pin functions remain the same, but the labeling of those pins might be different.
Located on the back of the LCD screen is the I2C interface board, and on the interface is an adjustable potentiometer. This adjustment is made with a small screwdriver. You will adjust the potentiometer until a series of rectangles appear – this will allow you to see your programming results.
The Arduino module and editor do not know how to communicate with the I2C interface on the LCD. The parameter to enable the Arduino to send commands to the LCD are in separately downloaded LiquidCrystal_I2C library.
Before installing LiquidCrystal_I2C, remove any other libraries that may reside in the Arduino IDE with the same LiquidCrystal_I2C name. Doing this will ensure that only the known good library is in use. LiquidCrystal_I2C works in combination with the preinstalled Wire.h library in the Arduino editor.
To install the LiquidCrystal_I2C library, use the SketchSketch > Include Library > Add .ZIP Library…from the Arduino IDE (see example). Point to the LiquidCrystal_I2C-master.zip which you previously downloaded and the Library will be installed and set up for use.
Several examples and code are included in the Library installation, which can provide some reference and programming examples. You can use these example sketches as a basis for developing your own code for the LCD display module.
There may be situations where you should uninstall the Arduino IDE. The reason for this could be due to Library conflicts or other configuration issues. There are a few simple steps to uninstalling the IDE.
The I2c address can be changed by shorting the address solder pads on the I2C module. You will need to know the actual address of the LCD before you can start using it.
Once you have the LCD connected and have determined the I2C address, you can proceed to write code to display on the screen. The code segment below is a complete sketch ready for downloading to your Arduino.
The code assumes the I2C address of the LCD screen is at 0x27 and can be adjusted on the LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27,16,2); as required.
Similar to the cursor() function, this will create a block-style cursor. Displayed at the position of the next character to be printed and displays as a blinking rectangle.
This function turns off any characters displayed to the LCD. The text will not be cleared from the LCD memory; rather, it is turned off. The LCD will show the screen again when display() is executed.
After 40 spaces, the function will loop back to the first character. With this function in the loop part of your sketch, you can build a scrolling text function.
Scrolling text if you want to print more than 16 or 20 characters in one line then the scrolling text function is convenient. First, the substring with the maximum of characters per line is printed, moving the start column from right to left on the LCD screen. Then the first character is dropped, and the next character is displayed to the substring. This process repeats until the full string has been displayed on the screen.
The LCD driver backpack has an exciting additional feature allowing you to create custom characters (glyph) for use on the screen. Your custom characters work with both the 16×2 and 20×4 LCD units.
A custom character allows you to display any pattern of dots on a 5×8 matrix which makes up each character. You have full control of the design to be displayed.
To aid in creating your custom characters, there are a number of useful tools available on Internet. Here is a LCD Custom Character Generator which we have used.
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.
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 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.
Let’s see how to connect the LCD module to Arduino. For that first, connect the VSS to the GND and VDD to the 5V. To use the LCD backlight, connect the backlight Anode to the 5V and connect the backlight cathode to the GND through a 220Ωresistor. Since we are not using the read function connect the LCD R/W pin to the GND too. To adjust the contrast, connect the centre pin of a 10KΩ trimmer resistor to the VEE pin and connect the side pins to the VCC and GND. Now connect the registry select pin to D12 and Enable pin to D11.
Now let’s connect the data pins. The LCD module can work in two modes, 8-bit and 4-bit. 8-bit mode is faster but it will need 8 pins for data transfer. In 4-bit mode, we only need four pins for data. But it is slower since the data is sent one nibble at a time. 4-bit mode is often used to save I/O pins, while the 8-bit mode is used when speed is necessary. For this tutorial, we will be using the 4-bit mode. For that connect the D4, D5, D6 and D7 pins from the LCD to the D5, D4, D3 and D2 pins of the Arduino.
The following Arduino 16x2 LCD code will print Hello, World! on the first line of the display and the time the Arduino was running in seconds on the second line.
Now let’s discuss the code. As usual, the sketch starts by including the necessary libraries. For this tutorial, we will be including the LiquidCrystal library from Arduino. This library is compatible with LCDs based on the Hitachi HD44780, or any compatible chipset. You can find more details about this library on the Arduino website.
Let’s create an object to use with the LiquidCrystal library. The following line of code will create an object called lcd. We will be using this object in the entire code to access the library functions. The object is initialized with the pin numbers.
Now let’s look at the setup()function. The lcd.begin function is used to initialize the LCD module. This function will send all the initialization commands. The parameters used while calling this function are the number of columns and the number of rows. And the next function is lcd.print. with this function, we have printed the word Circuit Digest! to the LCD. Since the LCD cursor is set to home position within the lcd.begin, we don’t need to set any cursor position. This text will stay there for two seconds. After that, the text will scroll from left to right until the entire text is out of the display. To scroll the display to the right, we have used the function lcd.scrollDisplayRight. After that, to clear display, we used lcd.clear, this will clear any characters on the display.
Now let’s look at theloop function. The for loop will count from 0 to 9, and when it reaches 9, it will reset the count and repeat the process all over again. lcd.setCursor is used to set the cursor position. lcd.setCursor(8, 1) will set the LCD cursor to the eighth position in the second row. In the LCD, the first row is addressed as 0 and the second row is addressed as 1. And the lcd.print(i) will print the count value stored in the variable i to the display.
Wrong characters are displayed: This problem occurs usually when the LCD is not getting the correct data. Make sure you are sending the correct ASCII value. If you are sending the correct ASCII characters, but still showing the wrong one on the LCD, check your connections for loose contact or short circuits.
Display shows Black boxes or does not show anything: First thing to do in these situations is to adjust the contrast voltage by rotating the variable resistor. This will correct the contrast value and will give you a visible readout.
Contrast is Ok, but still no display: Make sure to provide a sufficient time delay in between sending each character. Because if you don’t give enough time to process the data the display will malfunction.
Contrast and delay are ok, but still no display: Make sure you are powering the LCD from a 5V source. By default, these displays won’t work with a supply voltage below 5V. So if you are using the display with a 3.3V microcontroller make sure to power the display from 5V and use level shifters in between the display and the microcontroller.
In this project we will provide the input voice using Google Voice Keyboard via a Android App (BlueTerm) and print the text on 16x2 LCD using Raspberry Pi.
In this tutorial we are interfacing a Liquid Crystal Display (LCD) module with the Raspberry Pi Pico using Micropython to display strings, and characters on the LCD.
We used some Python scripts to find the local IP address of your Raspberry Pi on the network and display it on the 16x2 LCD Screen. We also added the script in the Crontab so that it can be run on every 10 minutes and we will have the updated IP address every time.
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.
The 3-in-1 Smart Car and IOT Learning Kit from SunFounder has everything you need to learn how to master the Arduino. It includes all of the parts, wiring diagrams, code, and step-by-step instructions for 58 different robotics and internet of things projects that are super fun to build!
Here’s a diagram of the pins on the LCD I’m using. The connections from each pin to the Arduino will be the same, but your pins might be arranged differently on the LCD. Be sure to check the datasheet or look for labels on your particular LCD:
Also, you might need to solder a 16 pin header to your LCD before connecting it to a breadboard. Follow the diagram below to wire the LCD to your Arduino:
All of the code below uses the LiquidCrystal library that comes pre-installed with the Arduino IDE. A library is a set of functions that can be easily added to a program in an abbreviated format.
In order to use a library, it needs be included in the program. Line 1 in the code below does this with the command #include
Now we’re ready to get into the programming! I’ll go over more interesting things you can do in a moment, but for now lets just run a simple test program. This program will print “hello, world!” to the screen. Enter this code into the Arduino IDE and upload it to the board:
TheLiquidCrystal() function sets the pins the Arduino uses to connect to the LCD. You can use any of the Arduino’s digital pins to control the LCD. Just put the Arduino pin numbers inside the parentheses in this order:
This function sets the dimensions of the LCD. It needs to be placed before any other LiquidCrystal function in the void setup() section of the program. The number of rows and columns are specified as lcd.begin(columns, rows). For a 16×2 LCD, you would use lcd.begin(16, 2), and for a 20×4 LCD you would use lcd.begin(20, 4).
This function clears any text or data already displayed on the LCD. If you use lcd.clear() with lcd.print() and the delay() function in the void loop() section, you can make a simple blinking text program:
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:
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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Ms.Josey 
Ms.Josey