interfacing 16x2 lcd display with pic microcontroller quotation

In this session we will see how to interface 16×2 LCD to PIC18F4550 microcontroller which is of family PIC18F. You can get information of 16×2 LCD in the session

PIC18F4550 belongs to the PIC18F family; PIC18F4550 is an 8bit microcontroller and uses RISC architecture. PIC18F4550 has 40 pins in PDIP (dual in line package) and 44 pin in TQFP (Quad flat package).

32KB flash memory, 2048 bytes of SRAM (synchronous Random Access memory), EEPROM (Electrically Erasable Program Read Only Memory) of 256 bytes are embedded in the PIC18F4550.

It has 35 I/O pins for interfacing and communication with other peripherals, 13channel of 10bit analog to digital converters which are used for interfacing and communicating the analog peripherals (DC motor, LDR, etc.).

PIC18F4550 has SPI (serial peripheral interface) and i2c (inter integrated circuit) for master and slave modes. It has SPP (Streaming Parallel Port) for USB streaming transfer.

PIC18F4550 is embedded with 4 timer modules (timer0 to timer3), 2 comparator modules and 3 external interrupt. It has Dual Oscillator options allow microcontroller and USB module to run at different clock speeds. It can operate in 2.0V to 5.5V

The resistor R1 is used for giving the contrast to the LCD. The crystal oscillator of 12 MHz is connected to the OSC1 and OSC2 pins of Pic microcontroller PIC18F4550 for system clock. The capacitor C2 and C3 will act filters to the crystal oscillator. You can use different ports or pins for interfacing the LCD before going to different ports please check the data sheet whether the pins for general purpose or they are special function pins.

Interfacing LCD to PIC is not different from interfacing to 8051. The basic concept and gist of the programming is almost same. Visit the following link for more information

Only the pins, registers and architecture using for interfacing will be different. When we look at the program, functions like initialization, sending data to the LCD will be almost same.

In the pic programming also for initializing the LCD the R/W pin should be low for writing the data, Enable pins should be high and register select pin (RS) should be high for writing the data. For sending a command the RS should be low, R/W pin should be low and enable pin should be high.

Install MPLAB in your system and create a new project, in selecting device and family select PIC18F family and add PIC18F4550 controller to your project.

This is our sixth tutorial in our PIC Tutorial Series, in this tutorial we learn Interfacing of 16x2 LCD with PIC Microcontroller. In our previous tutorials we have learnt the basics of PIC using some LED blinking Programs and have also learnt How to use Timers in PIC Microcontroller. You can check here all the tutorials on Learning PIC Microcontrollers using MPLABX and XC8 compiler.

This tutorial will be an interesting one because we will learn How to Interface 16×2 LCD with PIC16F877A, check the detailed Video at the end this tutorial. Gone are the old days where we used LEDs for user indications. Let us see how we can make our projects look more cool and useful by using LCD displays. Also check our previous articles on Interfacing LCD with 8051, with Arduino, with Raspberry Pi, with AVR.

To make things easier we have made a small librarythat could make things easy while using this LCD with our PIC16F877A. The header file "MyLCD.h" is given here for download, which contains all the necessary function to drive the LCD using PIC MCU. Library code is well explained by comment lines but if you still have doubts reach us through the comment section. Also check this article for Basic LCD working and its Pinouts.

Now, there are two ways to add this code into your program. You can either copy all the above lines of code in MyLCD.h and paste them before the void main(). Or you can download the header file using the link and add them to the header file of your project (#include " MyLCD.h ";). This can be done by right clicking on the header file and selecting Add existing Item and browsing to this header file.

Here I have copied and pasted the header file code into my main C file. So if you are using our code, then you don’t need to download and add the header file into your program, just use the complete Code given at the end of this Tutorial. Also note that this library will only support PIC16F series PIC Microcontroller.

void Lcd_Start():This function should be the first function that has to be called to start working with our LCD. We should call this function only once to avoid lag in the program.

void Lcd_Set_Cursor(x pos, y pos):Once started, our LCD is ready to take commands, we can instruct the LCD to set its cursor in you preferred location by using this function.  Suppose if, we need out cursor at 5th character of 1st row. Then the function will be void Lcd_Set_Cursor(1, 5)

Each time the Lcd_Print_Char(char data)is called, its respective character values is sent to the data-lines of the LCD. These characters reach the HD44780U in form of bits. Now this IC relates the bits to the character to be displayed by using its ROM memory as shown the below table. You can find bits for all the characters in the datasheet of HD44780U LCD Controller.

Now, since we are satisfied with our header file let’s build the circuit and test the program. Also check complete header file given in the link given above.

The hardware for this project is very simple. We are going to reuse the same PIC module that we used last time and connect the LCD module to our PIC using jumper wires.

I"m designing a digital incubator using a DHT-22 sensor and a 16x2 LCD. I programmed the pic to display my name and the title of my project before displaying the temperature and humidity, but I don"t have the DHT-22 sensor yet.

In the simulation, when I disconnected the DHT-22 sensor, it displayed just my name and title and then blanked out but when I did the hardware connection it displayed gibberish. I used mikroC to code the project. I don"t know if the fault is from my end or because I didn"t connect the sensor.

In this tutorial, we’ll discuss how Alphanumeric LCD works and how to interface a 16×2 LCD with a microcontroller. You’ll learn how LCD (Liquid Crystal Display) works internally and how to send data and commands to it with a microcontroller, specifically PIC MCUs. And you’ll also learn how to develop a simple LCD Driver for your upcoming projects.

There are 2 practical LABs associated with this tutorial and here is a brief animation indicating what you’ll be able to do after completing this tutorial.

We typically add a 16×2 Alphanumeric LCD to small embedded systems & projects to enhance the user experience and UI of the device/project. You can use it to display text messages to the user, number, etc. Other types of LCDs provide different features such as the number of columns and rows (characters) and maybe colored display, and also different interfaces (parallel, spi, i2c, etc).

For this tutorial, we’ll consider the 16×2 LCD with a 16-pin header interface. Assuming it has the standard Hitachi LCD driver HD44780 controller. We’ll see how it works internally and how to interface it with microcontrollers. This small IC on the backside of the LCD module controls the LCD itself and accepts user commands and data sent by the master MCU.

The LCD module consists of 16×2 character cells, and each one of them is 5×8 dots. Controlling all of this is a tedious task for our main microcontroller to do. However, it doesn’t have to do. As there is a specific function controller on the LCD itself controlling the display while reading in the user’s commands & data. Here, I’ll be considering the Hitachi HD44780 controller.

The HD44780U has two 8-bit registers, an instruction register (IR) and a data register (DR). The IR stores instruction codes, such as display clear and cursor shift, and address information for display data RAM (DDRAM) and character generator RAM (CGRAM). The IR can only be written from the MPU. The DR temporarily stores data to be written into DDRAM or CGRAM and temporarily stores data to be read from DDRAM or CGRAM. Data written into the DR from the MPU is automatically written into DDRAM or CGRAM by an internal operation.

Display data RAM (DDRAM) stores display data represented in 8-bit character codes. Its extended capacity is 80 × 8 bits, or 80 characters. The area in display data RAM (DDRAM) that is not used for display can be used as general data RAM. Therefore, whatever data you send to the DDRAM, it’ll get displayed on the LCD. As long as the characters count is below 32 (for 16×2 LCD), it’ll be visible. Otherwise, written characters are stored in the DDRAM but not visible.

The table down below shows you the standard ASCII equivalent characters for the LCD display stored in the CGROM. And you can also create your custom characters and symbols if you want to, as we’ll see in a future tutorial. Note the “A” character which has a binary code of (0100 0001)b this is equivalent to 65 (the ASCII value for A in the ASCII table).

The cursor/blink control circuit generates the cursor or character blinking. The cursor or the blinking will appear with the digit located at the display data RAM (DDRAM) address set in the address counter (AC).

There are two ways to interface the LCD diver (controller) IC. You can use the full bus width (8-Bits) for data or alternatively you can use a 4-Bit interface for a reduced pin count needed to control the LCD. Specifically low pin count MCUs need to operate in the 4-Bit mode.

At the beginning of your system’s firmware, you should do some initialization steps for the LCD display before it’s usable. These steps are listed by the manufacturer of the LCD Driver IC and let your LCD know how it’s going to operate afterward. Which interface mode you’ll be using (4 or 8 bits), which font and so on.

The LCD takes some time to process commands or data. Therefore, there must be a small delay before issuing a new command to the LCD. This delay could be chosen arbitrarily as long as it’s longer than the time required by the LCD itself as indicated in the datasheet. Alternatively, you can just read the busy flag bit to know whether the previous command was successfully processed or not.

When a data or a command is sent to the LCD, the BF or D7 bit of the LCD becomes 1 and as soon as the command is successfully processed, the BF becomes 0.

And here is another table for some commands examples that you can test yourself. We’ll implement a couple of them in the following practical LABs and the rest are left for you to experiment with.

First of all, we should define the IO pins which we’ll be using to interface the LCD. It’s a recommended practice to isolate the hardware drivers firmware from the application layer and for the sake of portability of your code. This step makes your code less dependent on the specific MCU chip you’re using in the current project.

if at any point you found out that a specific pin must be changed, it’ll be an easy task to change it without searching your code and replacing each and every single occurrence for that line of code.

We’ll be using the 4-Bit interface in these tutorials as it’s the most common and most wished for. Nobody wants to consume all of his microcontroller’s pins just to hook an LCD. In fact, there is an I2C interface for the LCD which we’ll be using in a future tutorial and its main feature is reducing the pin count used for LCD control.

All in all, what we need now is a routine to parse out half-a-byte of data and send these bits to the corresponding pins of the IO pins associated with LCD Data. Here is a simple implementation for such a routine.

As we’ve discussed earlier in this tutorial, sending a command to the LCD should start with selecting the command register. Then the command data is transferred to the LCD io data pins. Then we should clock or send enable signal pulse. This routine is followed in general settings, whether it’s a 4-Bit interface of an 8-Bit.

Now, it’s time to create the LCD initialization routine. This function is an exact implementation of the steps we’ve discussed earlier in this tutorial. The 4-Bit interface initialization steps are indicated in a previous flow chart and our task right now is to implement it in C.

Sending an 8-Bit character to the LCD followed by an enable pulse (clock) will display that character on the LCD. However, in our case of using a 4-Bit interface, this step will be divided into two consequent steps. First of which is parsing the 8-Bit character into a high_nibble and low_nibble. Then we’ll send the high4 bits first followed by an EN clock, then we’ll send the low4 bits followed by another EN clock. And that’s it!

To send a string to the LCD, we’ll need a loop to repeatedly send characters to the LCD until a buffer end is found, and typically it’s the NULL character “\0”. Here is the implementation of this routine.

As you’ve seen in the previous sections, the datasheet of the LCD driver IC includes all the command that it could handle. And we’re going to add a couple of them to our LCD Driver code. All the rest are left for you to experiment with. Some specific commands may help you in specific projects and it’s up to you to decide on which one you need to implement.

The commands I’m going to implement in this section are the most used ones in different projects. And will help you get more familiar with sending commands in 4-Bit mode. And there is no difference from what we’ve done so far.

The header file includes only the declarations of sub-routines with simple documentation indicating the functionality of each routine and what it takes and returns if it’s not void, etc. The LCD.h header file will be something like this

It’s now way more clean/clear. And it’s easier to debug or extend the functionality of your LCD driver module. Here is the compiled project, download it and customize it as you wish.

Open the MPLAB IDE and create a new project name it “LCD_16x2_LAB1”. If you have some issues doing so, you can always refer to the previous tutorial using the link below.

Open the MPLAB IDE and create a new project name it “LCD_16x2_LAB2”. If you have some issues doing so, you can always refer to the previous tutorial using the link below.

In this tutorial, we’ve implemented some of the most common LCD commands that you are most likely to use in your various projects. However, there still are some other commands that you can implement and test on your own. Just get the datasheet and start tinkering around and if you feel stuck at any point, just drop me a comment and I’ll be here to help you.

As we’ve discussed in a previous section, it’s a recommended practice to separate your device drivers layer from the application layer as much as possible. It helps in terms of portability and enhances code re-usability. Each device driver should have a header file .h and a source file .c and you can #include this library in whichever project you want. Reducing the time to port your project to another platform (microcontroller).

You can use the sprintf function from the standard library by including stdio.h. Now you can combine numbers (int, float, etc) with text in a single array “string” that you can print out on your LCD. We’ve done this in a previous lab for the LM35 sensor.

Thearduino LCD Keypad shieldis developed for Arduino compatible boards, to provide a user-friendly interface that allows users to go through the menu, make selections etc. It consists of a 1602 white character blue backlight LCD. The keypad consists of 5 keys select, up, right, down and left. To save the digital IO pins, the keypad interface uses only one ADC channel. The key value is read through a 5-stage voltage divider.

In this tutorial, you will learn to interface anLCD with a pic microcontroller. It is very simple and easy to understand the project for beginners and is commonly used in several electronic products. LCD (Liquid Crystal Display)provides a user-friendly interface and can be very useful for debugging purposes. After completion of this tutorial, you will be able to display data on an LCD using MPLAB XC8 Compiler and Mikro C compiler. We will provide examples with two Compilers such as MPLAB XC8 Compiler and Mikro C for PIC.

The reason LCD is more popular than LED, Seven Segment displays. Because we can display characters, numbers and custom characters with ease ( Just by easily programming a module).

First of all, to interface LCD with a pic microcontroller, we used GPIO pins.  GPIO pins are general-purpose input-output pins. Because we send control and data signals to LCD through these I/O pins.  Therefore, you should know how to use digital input-output pins of the pic microcontroller. To know about GPIO pins programming, check these tutorials:

It can work in two modes, 4-bit and 8-bit. In this tutorial, we have used the 4-bit mode which uses only 4 data lines, thus saving pins of the microcontroller. So It is recommended to use LCD in four bits mode to save pins of the microcontroller for other applications.

As you can see in this diagram, if we use 8-bit mode interfacing, we will need to use 11 pins of pic microcontroller. On the other hand, if we use 4-bit mode, we need only 6 GPIO pins. Therefore, it is recommended to use 4-bit mode interfacing.  The only difference between  4-bit and 8-bit is that data transfer speed is faster for 8-bit mode. However, it doesn’t make any major difference.

A variable resistor is used to adjust the contrast of 5×8 dot pixels according to background light. Therefore, if you are not able to see anything on LCD after programming, the maximum changes are that you need to adjust contrast with the variable resistor. This contrast register makes adjust to the voltage applied on the VEE pin.

For MPLAB XC8 Compiler, we will use the PIC18F4550 microcontroller. For MikroC Pro for PIC, we will use the PIC16F877A microcontroller. In the case of MPLAB XC8, we will develop our own LCD library. Because the XC8 compiler does not provide built-in libraries. In the contrary, MikroC Pro provides libraries for all modules such as LCD, Keypad, ADC Module, UART module.

In this section, we will see how to write example code for 16×2 LCD interfacing with PIC18F4550 microcontroller. Although, you can use see code with other Pic microcontrollers also.

As we mentioned earlier, we can use the 8-bit mode and 4-bit mode interfacing. But due to the efficient use of MCU pins, we will be using 4-bit Mode. To interface LCD, we follow these steps:

In this circuit, we used the PORTB of PIC18F4550. But you can use any PORT. To do this, we need to change the pin assignment inside the code. I will show you how to assign pins for LCD in the next section.

These lines define which pins of the pic microcontroller should connect with LCD. For instance, in this example, we used the PORTD of PIC18F4550 microcontroller. Connect RD0-RD3 pins with D4-D7 pins of LCD respectively and other pins with RW, EN, RS and Power pins. But you can change PORT to other PORT of PIC microcontroller also by changing the PORT name with these commands.

LCDWriteNibble() function is used to write a nibble. Nibble is basically a half a byte. Because we are using LCD in four bits mode. Therefore, we need to send 8-bit commands/data in four bits chunks. This function writes the specified nibble to the LCD.

Because we will use 4-bit mode, data and commands transfer in 4-bits format. Even it requires at least 8-bit to display a character. To resolve this issue, we send data in a 4-bits format two times.

void LCDPutChar(char ch): Writes a character to LCD at current cursor position. This function displays the specified ASCII character at the current position on the LCD.

LCDGoto(char pos, char ln): This function positions the cursor at the specified line and column. Column and line at which the cursor should be positioned between 0-15 for pos (column) and 0-1 for ln(row).

In last section, we have seen how to display ASCII characters or string. But in almost all practical projects, we need to display, integer, float values. This code displays the counter value which increments from 0-9 after every one second. This is the main function of code only. Because the rest of the code is same as the previous program example.

In this section, we will see how to interface LCD with pic microcontroller and programming examples using MikroC for pic. MikroC pro has a built-in library.

We have used 16×2 LCD which means there are 2 rows and 16 characters in each row. So we can display a total of 32 characters at a time in two rows with 16 characters in each row.

This is the main command which prints our text on LCD. It also gives the privilege to specify the position of the text. In the horizontal direction, we count rows number and in a vertical direction, we count the column number. In above command,

However if your string is longer than the number of characters that could be displayed in a row from the starting position, the last characters will not be displayed. E.g. Lcd_Out (1, 6 “LCD Interface”);will display text in row 1 starting from column position 6 and will display only LCD Interfacethe rest of the characters will not be displayed as there is no room for them.

void Lcd_Out_Cp(char *text);will start printing the text from the current cursor position. For example after printing Lcd_Out (1, 1, “LCD”);if you write Lcd_Out_Cp(“Hello”);it will display “Hello”at a position from column position of 4 in row 1.

void Lcd_Chr(char row, char column, char out_char);allows only single characters to be displayed at specified positions. E.g. Lcd_Chr(2, 5, ‘A’); will print only A on column 5 row 2.

void Lcd_Chr_Cp(char out_char); allows to print only single character from current cursor position like after Lcd_Chr(2, 5, ‘A’);if your writeLcd_Chr_Cp(‘B’);it will be printed at row 2 column 6.

To interface LCD withPIC16F877A and display the text ‘LCD INTERFACE’ on it. LCDs come in different sizes and shapes. For this project, we have selected a 16×2 character, alphanumeric LCD. It contains 2 rows of 16 character.

When using PIC microcontroller, the mikroC compiler has a built-in LCD library that supports the commands to carry out LCD initialization. The library consists of a number of functions to control LCDs with 4-bit data interface.

The main program first clears the LCD screen and then displays “LCD INTERFACE” in the first row of LCD. The LCD pin directions are all set as outputs. The RS pin of LCD is set to 1, which indicates that the information received from DB4-DB7 is a valid text to be printed on LCD screen. The EN pin is also set to 1 which indicates that data is send to the LCD.

Programmed LCDs are vastly used for industrial as well as commercial applications. LCDs are used in UPSs or inverters, where voltage and current readings are displayed on the screen. Instructions to be followed are displayed on an LCD screen in airports, banks, hospitals, etc. If you still have any issue after reading this article, feel free to comment on this post with your issues.

ERMC1602SBS-2 is 16 characters wide,2 rows character lcd module,SPLC780C controller (Industry-standard HD44780 compatible controller),6800 4/8-bit parallel interface,single led backlight with white color included can be dimmed easily with a resistor or PWM,stn- blue lcd negative,white text on the blue color,wide operating temperature range,rohs compliant,built in character set supports English/Japanese text, see the SPLC780C datasheet for the full character set. It"s optional for pin header connection,5V or 3.3V power supply and I2C adapter board for arduino.

It"s easily controlled by MCU such as 8051,PIC,AVR,ARDUINO,ARM and Raspberry Pi.It can be used in any embedded systems,industrial device,security,medical and hand-held equipment.

Of course, we wouldn"t just leave you with a datasheet and a "good luck!".For 8051 microcontroller user,we prepared the detailed tutorial such as interfacing, demo code and Development Kit at the bottom of this page.

The Hitachi HD44780 LCD controller is an alphanumeric dot matrix liquid crystal display (LCD) controller developed by Hitachi in the 1980s. The character set of the controller includes ASCII characters, Japanese Kana characters, and some symbols in two 40 character lines. Using an extension driver, the device can display up to 80 characters.

The Hitachi HD44780 LCD controller is limited to monochrome text displays and is often used in copiers, fax machines, laser printers, industrial test equipment, and networking equipment, such as routers and storage devices.

Compatible LCD screens are manufactured in several standard configurations. Common sizes are one row of eight characters (8×1), and 16×2, 20×2 and 20×4 formats. Larger custom sizes are made with 32, 40 and 80 characters and with 1, 2, 4 or 8 lines. The most commonly manufactured larger configuration is 40×4 characters, which requires two individually addressable HD44780 controllers with expansion chips as a single HD44780 chip can only address up to 80 characters.

Character LCDs may have a backlight, which may be LED, fluorescent, or electroluminescent. The nominal operating voltage for LED backlights is 5V at full brightness, with dimming at lower voltages dependent on the details such as LED color. Non-LED backlights often require higher voltages.

Character LCDs use a 16-contact interface, commonly using pins or card edge connections on 0.1 inch (2.54 mm) centers. Those without backlights may have only 14 pins, omitting the two pins powering the light. This interface was designed to be easily hooked up to the Intel MCS-51 XRAM interface, using only two address pins, which allowed displaying text on LCD using simple MOVX commands, offering cost effective option for adding text display to devices.

Vee (also V0): This is an analog input, typically connected to a potentiometer. The user must be able to control this voltage independent of all other adjustments, in order to optimise visibility of the display that varies i. a. with temperature and, in some cases, height above the sea level. With a wrong adjustment, the display will seem to malfunction.

In 8-bit mode, all transfers happen in one cycle of the enable pin (E) with all 8 bits on the data bus and the RS and R/W pins stable. In 4-bit mode, data are transferred as pairs of 4-bit "nibbles" on the upper data pins, D7–D4, with two enable pulses and the RS and R/W pins stable. The four most significant bits (7–4) must be written first, followed by the four least significant bits (3–0). The high/low sequence must be completed each time or the controller will not properly receive further commands.

Selecting 4-bit or 8-bit mode requires careful selection of commands. There are two primary considerations. First, with D3–D0 unconnected, these lines will always appear high (binary 1111) to the HD44780 since there are internal pull-up MOSFETs.

The same command is sent three times, Function Set with 8-bit interface D7–D4 = binary 0011, the lower four bits are "don"t care", using single enable pulses. If the controller is in 4-bit mode, the lower four bits are ignored so they cannot be sent until the interface is in a known size configuration.

In all three starting cases, the bus interface is now in 8-bit mode, 1 line, 5×8 characters. If a different configuration 8-bit mode is desired, an 8-bit bus Function Set command should be sent to set the full parameters. If 4-bit mode is desired, binary 0010 should be sent on D7–D4 with a single enable pulse. Now the controller will be in 4-bit mode and a full 4-bit bus Function Set command sequence (two enables with command bits 7–4 and 3–0 on subsequent cycles) will complete the configuration of the Function Set register.

The execution times listed in this table are based on an oscillator frequency of 270 kHz. The data sheet indicates that for a resistor of 91 kΩ at VCC=5 V the oscillator can vary between 190 kHz and 350 kHz resulting in wait times of 52.6 µs and 28.6 µs instead of 37 µs. If a display with the recommended 91 kΩ resistor is powered from 3.3 volts the oscillator will run much slower. If the busy bit is not used and instructions are timed by the external circuitry, this should be taken into account.

The original HD44780 character generator ROM contains 208 characters in a 5×8 dot matrix, and 32 characters in a 5×10 dot matrix. More recent compatible chips are available with higher resolution, matched to displays with more pixels.

Huang, Han-Way (2009). The HCS12 / 9S12: An Introduction to Software and Hardware Interfacing (2nd ed.). Delmar Cengage Learning. ISBN 978-1-4354-2742-6.