hitachi hd44780 lcd display quotation
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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.
R/W: In most applications, reading from the HD44780 is not necessary. In that case, this pin can be permanently connected to ground and no processor pins need to be allocated to control it.
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 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.
We can store all data that is read from the LCD in one byte (8 bits). This will be stored in an 8 bit integer (same as a char type). For ease of access, we use an 8bit unsigned integer as defined in
We loop to get data out of the LCD. The first loop is generic and gets executed no matter whether the LCD is in 8 bit mode or 4 bit mode. The process is simple:
Read the first pin (i = 0), this is the least significant digit. In 4 bit mode, this would be data pin 4 on the LCD board, in 8 bit mode, this would be data pin 0. The output is either a HIGH (1) or LOW (0). Let the reading be the bit [D0]. It gets bitshifted by zero places to the left. The operation performed will be:
This process gets repeated until the upper limit is reached. If the display was operating on 8 bit mode, we end up with the full byte by the end of the loop, and it is returned. If the display is in 4 bit mode, we only have one nibble [D3][D2][D1][D0], the if clause executes.
This is obviously a backend to be used by other functions which will filter the data for the end user. At some point in time in the execution, the LCD"s output gets corrupted, some things disappear.
Blue 16x2 LCD module featuring 2 rows consisting each of 16 characters. The module is compatible with the Hitachi HD44780 controller, and is commonly used in Arduino and other microcontroller projects.
Blue 16x2 LCD module featuring 2 rows consisting each of 16 characters. The module is compatible with the Hitachi HD44780 controller, and is commonly used in Arduino and other microcontroller projects.
Character based LCD displays are great: they are inexpensive, and it is rather simple to use them compared to graphical displays. Yes, they only can display text and custom symbols, but this is usually what I need. And pretty much all character displays are using the Hitachi HD44780 protocol, so it is a de-facto industry standard.
These displays have one big disadvantage: they need to be compatible with the original Hitachi interface and protocol. First display were mostly one line only, and had only few characters, typically up to 16. The protocol worked either with one or two lines on the display. Today’s display have usually two lines, with 16 characters. But what if I need more?
These HD44780 displays can run in 4bit or 8bit mode, and in the smallest configuration (4bit mode) the connection to the microcontroller only needs 6 wires:
The original protocol had a big problem: there is no handshaking between microcontroller and display. If the microcontroller writes to the display, it needs to wait until the display has finished the operation until a new write operation can start. So the micrcontroller needs to wait some time, depending on the display speed. To overcome this problem, later displays had added the R/W (Read/Write) signal which allows the microcontroller to read the status from the display (if the display is ready to accept new data). So if you consider to use a display, make sure it has that R/W line implemented.
So writing at address 0x00 would be the first character on line 1, 0x01 the second, and so on. Writing at address 0x40 would be the first character on the second line, and so on. That would allow up to 64 characters per line. A 16-character display would show the characters e.g. from address 0x00-0x0F. The other bytes in the address map could be used to ‘scroll’ the text to the right/left using special display commands:
As this feature has not been used much, and there was a bigger customer needs for having 4 lines of text, some vendors decided to change the memory map to support 4 lines (see “Character LCD with 4 Lines”):
If I want now to have 4 lines with more than 16 characters, something different is needed. My display driver (LCDHTA, see “HD44780 2×16 Character Display for Kinetis and Freedom Board“) worked fine, but not for a 4×40 display which was used by a reader of this blog :-(: the NewHaven NHD-0440WH-ATFH-JT Display:
Until I realized: they have put 2 display controller together! This display is not really a 4×40 character display, it is two 2×40 displays in a single display packaging :-). This is the same as if I would combine two displays on the same bus like this:
As I did not had the Newhaven 4×40 display available to verify the driver, I wired two 2×16 displays together. And with this, I was able to build a 4×16 (potentially 4×64) character display:
The Hitachi HD44780 is very common and can be considered as ‘industry standard’. But as with any standards, it comes with limitations, and standards sometimes make it hard to move the technology to the next level. And sometimes it causes kind of strange solutions as creating a 4 line display with two display controllers on it. Switching the Ex lines I can now support up to for 4 lines and up to 64 characters for each line. And if needed, I can extend that concept for more lines/displays.
Character based LCD displays are great: they are inexpensive, and it is rather simple to use them compared to graphical displays. Yes, they only can display text and custom symbols, but this is usually what I need. And pretty much all character displays are using the Hitachi HD44780 protocol, so it is a de-facto industry standard.
These displays have one big disadvantage: they need to be compatible with the original Hitachi interface and protocol. First display were mostly one line only, and had only few characters, typically up to 16. The protocol worked either with one or two lines on the display. Today’s display have usually two lines, with 16 characters. But what if I need more?
These HD44780 displays can run in 4bit or 8bit mode, and in the smallest configuration (4bit mode) the connection to the microcontroller only needs 6 wires:
The original protocol had a big problem: there is no handshaking between microcontroller and display. If the microcontroller writes to the display, it needs to wait until the display has finished the operation until a new write operation can start. So the micrcontroller needs to wait some time, depending on the display speed. To overcome this problem, later displays had added the R/W (Read/Write) signal which allows the microcontroller to read the status from the display (if the display is ready to accept new data). So if you consider to use a display, make sure it has that R/W line implemented.
So writing at address 0x00 would be the first character on line 1, 0x01 the second, and so on. Writing at address 0x40 would be the first character on the second line, and so on. That would allow up to 64 characters per line. A 16-character display would show the characters e.g. from address 0x00-0x0F. The other bytes in the address map could be used to ‘scroll’ the text to the right/left using special display commands:
As this feature has not been used much, and there was a bigger customer needs for having 4 lines of text, some vendors decided to change the memory map to support 4 lines (see “Character LCD with 4 Lines”):
If I want now to have 4 lines with more than 16 characters, something different is needed. My display driver (LCDHTA, see “HD44780 2×16 Character Display for Kinetis and Freedom Board“) worked fine, but not for a 4×40 display which was used by a reader of this blog :-(: the NewHaven NHD-0440WH-ATFH-JT Display:
Until I realized: they have put 2 display controller together! This display is not really a 4×40 character display, it is two 2×40 displays in a single display packaging :-). This is the same as if I would combine two displays on the same bus like this:
As I did not had the Newhaven 4×40 display available to verify the driver, I wired two 2×16 displays together. And with this, I was able to build a 4×16 (potentially 4×64) character display:
The Hitachi HD44780 is very common and can be considered as ‘industry standard’. But as with any standards, it comes with limitations, and standards sometimes make it hard to move the technology to the next level. And sometimes it causes kind of strange solutions as creating a 4 line display with two display controllers on it. Switching the Ex lines I can now support up to for 4 lines and up to 64 characters for each line. And if needed, I can extend that concept for more lines/displays.
HD44780 character LCD"s are easy to use, readily available, affordable and require very little processor overhead making them a great addition to any hacker"s toolbox. This book acquaints the user with character LCD"s and how to interface with the HD44780 LCD controller. It provides sections on connecting, setting up and displaying characters on the LCD.
Includes step by step instructions and easy to follow supporting comments. Download this book and learn how to add character LCD"s to your next project.
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.
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:
There are 19 different functions in the LiquidCrystal library available for us to use. These functions do things like change the position of the text, move text across the screen, or make the display turn on or off. What follows is a short description of each function, and how to use it in a program.
TheLiquidCrystal() function sets the pins the Arduino uses to connect to the LCD. You can use any of the Arduino’s digital pins to control the LCD. Just put the Arduino pin numbers inside the parentheses in this order:
This function sets the dimensions of the LCD. It needs to be placed before any other LiquidCrystal function in the void setup() section of the program. The number of rows and columns are specified as lcd.begin(columns, rows). For a 16×2 LCD, you would use lcd.begin(16, 2), and for a 20×4 LCD you would use lcd.begin(20, 4).
This function clears any text or data already displayed on the LCD. If you use lcd.clear() with lcd.print() and the delay() function in the void loop() section, you can make a simple blinking text program:
Similar, but more useful than lcd.home() is lcd.setCursor(). This function places the cursor (and any printed text) at any position on the screen. It can be used in the void setup() or void loop() section of your program.
The cursor position is defined with lcd.setCursor(column, row). The column and row coordinates start from zero (0-15 and 0-1 respectively). For example, using lcd.setCursor(2, 1) in the void setup() section of the “hello, world!” program above prints “hello, world!” to the lower line and shifts it to the right two spaces:
You can use this function to write different types of data to the LCD, for example the reading from a temperature sensor, or the coordinates from a GPS module. You can also use it to print custom characters that you create yourself (more on this below). Use lcd.write() in the void setup() or void loop() section of your program.
The function lcd.noCursor() turns the cursor off. lcd.cursor() and lcd.noCursor() can be used together in the void loop() section to make a blinking cursor similar to what you see in many text input fields:
Cursors can be placed anywhere on the screen with the lcd.setCursor() function. This code places a blinking cursor directly below the exclamation point in “hello, world!”:
This function creates a block style cursor that blinks on and off at approximately 500 milliseconds per cycle. Use it in the void loop() section. The function lcd.noBlink() disables the blinking block cursor.
This function turns on any text or cursors that have been printed to the LCD screen. The function lcd.noDisplay() turns off any text or cursors printed to the LCD, without clearing it from the LCD’s memory.
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 (°):
Ms.Josey 
Ms.Josey