raspberry pi gpio lcd display quotation

Connecting an LCD display to your Raspberry Pi is sure to take any project up a notch. They’re great for displaying sensor readings, songs or internet radio stations, and stuff from the web like tweets and stock quotes. Whatever you choose to display, LCDs are a simple and inexpensive way to do it.

In this tutorial, I’ll show you two different ways to connect an LCD to the Raspberry Pi with the GPIO pins. The first way I’ll show you is in 8 bit mode, which uses 10 GPIO pins. Then I’ll show you how to connect it in 4 bit mode, and that uses only 6 pins. After we get the LCD hooked up I’ll show you how to program it with C, using Gordon Henderson’s WiringPi LCD library.

I’ll show you how to print text to the display, clear the screen, position the text, and control the cursor. You’ll also see how to scroll text, create custom characters, print data from a sensor, and print the date, time and IP address of your Pi.

There’s another way to connect your LCD that uses only two wires, called I2C. To see how to do that, check out our tutorial How to Set Up an I2C LCD on the Raspberry Pi.

Most people probably want to connect their LCD in 4 bit mode since it uses less wires. But in case you’re interested, I’ll show you how to connect it in 8 bit mode as well.

In 8 bit mode, each command or character is sent to the LCD as a single byte (8 bits) of data. The byte travels in parallel over 8 data wires, with each bit travelling through it’s own wire. 8 bit mode has twice the bandwidth as 4 bit mode, which in theory translates to higher data transfer speed. The main downside to 8 bit mode is that it uses up a lot of GPIO pins.

In 4 bit mode, each byte of data is sent to the LCD in two sets of 4 bits, one after the other, in what are known as the upper bits and lower bits. Although 8 bit mode transfers data about twice as fast as 4 bit mode, it takes a longer time for the LCD driver to process each byte than it takes to transmit the byte. So in reality, there isn’t really a noticeable difference in speed between 4 bit mode and 8 bit mode.

If you’ve never worked with C programs on the Raspberry Pi, you may want to read our article How to Write and Run a C Program on the Raspberry Pi first. It will explain how to write, compile, and run C programs.

WiringPi is a C module that makes it easy to program the LCD. If you already have WiringPi installed on your Pi, you can skip this section. If not, follow the steps below to install it:

WiringPi has it’s own pin numbering system that’s different from the Broadcom (BCM) and RPi physical (BOARD) pin numbering systems. All of the programs below use the WiringPi pin numbers.

To use different pins to connect the LCD, change the pin numbers defined in lines 5 to 14. You’ll need to convert the WiringPi pin numbers to the physical pin numbers of the Raspberry Pi. See here for a diagram you can use to convert between the different numbering systems.

To use the LCD in 4 bit mode, we need to set the bit mode number to 4 in the initialization function (line 20 below). The following code prints “Hello, world!” to the screen in 4 bit mode:

By default, text is printed to the screen at the top row, second column. To change the position, use lcdPosition(lcd, COLUMN, ROW). On a 16×2 LCD, the rows are numbered from 0 to 1, and the columns are numbered from 0 to 15.

The function lcdClear(lcd) clears the screen and sets the cursor position at the top row, first column. This program prints “This is how you” for two seconds, clears the screen, then prints “clear the screen” for another two seconds:

Each LCD character is a 5×8 array of pixels. You can create any pattern you want and display it on the LCD as a custom character. Up to 8 custom characters can be stored in the LCD memory at a time. This website has a nice visual way to generate the bit array used to define custom characters.

To print a single custom character, first define the character. For an example of this see lines 12 to 19 below. Then use the function lcdCharDef(lcd, 2, omega) to store the character in the LCD’s memory. The number 2 in this example is one of the 8 locations in the LCD’s character memory. The 8 locations are numbered 0-7. Then, print the character to the display with lcdPutchar(lcd, 2), where the number 2 is the character stored in memory location 2.

Here’s an example of using multiple custom characters that prints the Greek letters omega, pi, and mu, plus thermometer and water drop symbols for temperature and humidity:

As an example to show you how to display readings from a sensor, this program prints temperature and humidity readings to the LCD using a DHT11 temperature and humidity sensor. To see how to set up the DHT11 on the Raspberry Pi, see our article How to Set Up the DHT11 Humidity Sensor on the Raspberry Pi.

Hopefully this helped you get your LCD up and running on your Raspberry Pi. The programs above are just basic examples, so try combining them to create interesting effects and animations.

If you have any problems or questions about installing the LCD or programming it, just leave a comment below. And don’t forget to subscribe to get an email when we publish new articles. Talk to you next time!

I got a 7" LCD from Wavefront that comes with an small junction board, an FPC cable and a "RGB LCD HAT" card (pic attached). I know the 50-pin cable is something called a "reverse" or "flipped" FPC cable (meaning that the ends of the cable are flipped...not blue/blue-bare/bare but blue/bare-bare-blue).

I would like to find out if there are other 7" LCDs compatible with this setup and if there is a place to obtain the junction board/cable/RGB LCD HAT" combo if subsequent screens I get do not come with these (or uses that separate complete board that seems so popular that needs it"s own power and outputs HDMI to the the Pi via its HDMI connector).

I have scoured the Internet and can"t find much info. I"m hoping someone here has already traveled this path and can give me some bread crumbs. Thanks!

The Gert doesn"t really look much like the RGB LCD HAT image that I posted. My HAT uses a 40-pin GPIO ribbon cable for connecting to the LCD, not a VGA connector. About the only thing the Gert and the HAT have in common is the GPIO connector. I"ve attached another picture showing the opposite side (top) of the RGB LCD HAT.

I guess what my real question is--is there a way to tell from specs which LCD displays are compatible with the RGB LCD HAT as shown in my original post?

You need to work out the pinout of the FPC connector on that Waveshare board. The Gert VGA and your RGB LCD HAT are both using https://www.raspberrypi.org/documentati ... /README.md The sync, clock and enable GPIOs are fixed but you can select different colour depth settings which varies the number and arrangement of GPIO connections. The Gert VGA adapter has a simple resistor ladder DAC whilst your board is a passive wiring adapter that passes each line through.

The HDMI controller boards for bare LCD panels are available on eBay. You need to select your panel first and then search for the controller as the controller must state it is compatible with your chosen panel. They need to program it for your panel and supply the correct wiring harness.

Just FYI, I have attached the schematic for the RGB LCD HAT, but I think your suggestion is probably the best one--settle on a display and then find an adapter based on the display model number.

basically any lcd that matches the fpc pinout that the driver can support should work, as this board drives the panels directly instead of using resistors to generate an analog vga signal

The Gert doesn"t really look much like the RGB LCD HAT image that I posted. My HAT uses a 40-pin GPIO ribbon cable for connecting to the LCD, not a VGA connector. About the only thing the Gert and the HAT have in common is the GPIO connector. I"ve attached another picture showing the opposite side (top) of the RGB LCD HAT.

I guess what my real question is--is there a way to tell from specs which LCD displays are compatible with the RGB LCD HAT as shown in my original post?Raspberry-Pi-RGB-LCD-driver-board-DPI-driver-5-inch-7-inch-10-1-inch.jpg

When you say "driver" I guess I"m thinking of drivers in the traditional sense. And the RGB LCD HAT scenario doesn"t have a "driver," per se. The instructions indicate modding the config.txt file to add:

So the configuration of the HDMI interface is done thru the config.xtx file. I suspect that if electrically an interface board is correct, then it"s just a matter of getting the right values put into the config.txt file to get the display to function. It"s that "electrically" compatible part that may be tricky.

Edit: BTW, the RGB LCD HAT attaches to the GPIO (40 pins) and the cable coming off the RGB LCD HAT going to the LCD is 50 pin. Apparently, the RGB LCD HAT is doing some sort of 40-to-50 conversion.

When you say "driver" I guess I"m thinking of drivers in the traditional sense. And the RGB LCD HAT scenario doesn"t have a "driver," per se. The instructions indicate modding the config.txt file to add:

So the configuration of the HDMI interface is done thru the config.xtx file. I suspect that if electrically an interface board is correct, then it"s just a matter of getting the right values put into the config.txt file to get the display to function. It"s that "electrically" compatible part that may be tricky.

Edit: BTW, the RGB LCD HAT attaches to the GPIO (40 pins) and the cable coming off the RGB LCD HAT going to the LCD is 50 pin. Apparently, the RGB LCD HAT is doing some sort of 40-to-50 conversion.

Yes, sorry...I did mean Waveshare. The screen in your pic is the one I have. But I am caught between two scenarios. My design is dependent upon using the RGB LCD HAT interface, but I can find a lot of these screens for less than Waveshare wants for theirs, but those screens use a separate interface card (requiring its own 5V power supply) and goofy HDMI-to-HDMI short cable. The Waveshare implementation is much cleaner, IMHO.

So the issue I am facing, and the reason for my post, is that I need to find a way to qualify (pre-purchase) one or more of these other screens and use them with the RGB LCD HAT interface. I would just junk-bin the interface board and 5-button adjustment board and use the RGB LCD HAT interface instead. Of course, as some point I"ll see if I can get a deal for just the screen, which should be even cheaper without the additional boards.

I did buy my 1st such 7" LCD display for summer vacation last year and used it heavily for three weeks, then on and off until again heavily during this summer vacation. Unfortunately the display stopped working after two weeks.

I really like the 1024x600 resoultion, and don"t miss touch functionality for the 7" display, since I have touch as part of my 6$ at aliexpress wireless keyboards:

Computer monitors are great for office work, gaming, and browsing, but these displays can be large and power consuming. One display found in both the commercial and hobby world is the HD44780 16 x 2 display, which can display two lines of alphanumeric characters. In this tutorial, we will learn how to connect one to a Raspberry Pi and code it using the Python programming language!

The HD44780 has a number of registers and commands that are used to control the display, but getting the display to work can be somewhat tricky, especially for inexperienced users. This is why most coders will turn to libraries. They include prewritten code that has been proven to work. In this tutorial, we will be relying on two libraries to control the LCD: RPLCD and RPi.GPIO. Before we can continue, we need to install the RPLCD library by using the following command in a terminal window:

First, we need to import the RPi.GPIO library as GPIO. This will allow us to use the GPIO library and refer to it as “GPIO”, which is easier than RPi.GPIO. The next library that we need to include is the RPLCD library, which allows us to use the LCD. Therefore, the first two lines of code in our Python program will be:

CharLCD is a Python library that lets users access Adafruit character LCDs from a Raspberry Pi. Next, we need to tell the RPLCD library what pins we have connected the LCD to. In the Scheme-It schematic above, we connected the LCD pins to the following GPIO (using the BOARD numbering scheme). The Pi has two numbering schemes; BOARD and BCM. The BOARD numbering scheme refers to the I/O header whereas the BCM scheme refers to the GPIO numbers from the Broadcom IC. It is often easier to use BOARD scheme as you can count the pins to determine which one you need to use whereas the BCM scheme requires you to first choose a GPIO and then determine its pin number (BOARD).

Now that we have configured the LCD, it’s time to do a few tasks with it! The first function that we should learn to use is “write_string()”, which is used to write text to the LCD. Try the following command:

Writing predefined strings is not entirely helpful, and displaying variables can be very beneficial. Luckily for us, Python allows typecasting, where one variable can be converted into another variable. The example below shows how we can display a counter, which displays an integer on the LCD, along with a simple “Count” message.

Next, we’ll learn how to clear the display. Displays like those based around the HD44780 are static, and they remember what you tell them to display. However, this also means that when you want to write new data, you may need to clear the entire display. Therefore, you can use this clear function to clear the display:

Sometimes printing text on the top left of the display may not be desirable. In this case, you will need to change the cursor’s position. To do this, we can set the cursor_pos variable to a specific value. The example below sets the cursor position to row 2 (x) and column 0 (y).

At the end of your program, you should include the function “lcd.close()”, as this will free up the GPIO for other programs that may need to use them.

The Internet is full of real time data. Weather information, stock quotes, etc, can be obtained from different service providers. Since most of the Raspberry Pi computers come with Wifi, and it’s extremely easy to handle the data obtained from the Internet with Python, it makes sense to use Raspberry Pi to fetch data from the Internet automatically.

On the other hand, every Raspberry Pi comes with GPIOs, which can be used to connect different devices. For example, we can connect a 16 x 2 character LCD display to the Raspberry Pi.

A communication interface called I2C is frequently used by many devices. Any I2C device uses 4 pins: one for power, one for the ground, one for data (“SDA”) and one for clock signals (“SCL”). For instance, this character LCD display can be connected to Raspberry Pi or other microcontroller via I2C.

This all sounds complicated. Fortunately, Adafruit has created the CircuitPython library for the Raspberry Pi. With this library, we can use I2C devices on Raspberry Pi very easily.

To achieve the above learning outcomes, we will use a Raspberry Pi Zero W to fetch some weather data from the Internet, and display the fetched data on a character LCD screen:

We usually use a browser to look for information on the Internet. We type a URL in the browser, and the browser will display an HTML page. However, if you look at the source of a HTML page, you will see that HTML is actually kind of messy.

For example, the Hong Kong Observatory provides a set of Open Data API so it’s actually really easy to get the latest weather update from the Observatory. To get the latest local weather forcast, all you need to do is to enter this URL in the browser:

NOTE: You may see the term ‘RESTful APIs’ from time to time. Many of these data services are indeed RESTful APIs, which means you can interact with these services with standard HTTP methods (GET, POST, etc.). Since we only need to get this time, we won’t go into the details of RESTful APIs.

Next, we are going to install two Python libraries: Adafruit’s CircuitPython and the library for the LCD1602 display. Let’s create a new folder on the Raspberry Pi for this project inside the terminal.

Then, make sure that the Raspberry Pi Zero W is on the Internet. We will download the libraries from the Internet and install them. If everything is ready, use pip3 to install RPI.GPIO and adafruit-blinka:

NOTE: We only need cd_api.py and circuitpython_i2c_lcd.py only, so it’s better to just copy the python scripts and not to install the entire library.

Both board and busio are from the CircuitPython library. As you will see in a minute, you don’t need to worry about typing the wrong pin numbers when you initialize an I2C device if you use the CircuitPython library. Also, we import the I2cLcd class and the sleep function.

This is where the CircuitPython really shines: the exact same code can be used in other microcontrollers running CircuitPython! So if you get yourself a Circuit Playground Bluefruit, you can use the character LCD display with the exact same code.

DEFAULT_I2C_ADDR = 0x27 defines the address of character LCD display. Every I2C device has an address. This address is important because multiple I2C devices can be connected to the Raspberry Pi, and the Raspberry Pi needs that address to communicate with the device correctly. Finally, we create an instance of I2cLcd with the i2c object, the I2C address, the number of rows and the number of columns as the parameters for the constructor. The backlight is turned on by calling the backlight_on method.

NOTE: This particular LCD1602 display’s address is 0x27, but yours may have a different one. You may need to call busio.I2C.scan() to check the actual address, as described in this Adafruit guide.

Next, rather than printing out all the JSON data in the console, we extract the information that we want and display it on the LCD display. For example, we can just display the temperatures in different regions. Replace print(data) with the following lines of code:

For each entry in the temp_data array, we first clear the display by calling clear(). Then, we move the cursor to (0, 0), i.e. the first position in the first row, and display the first 16 characters of the ‘place’ entry (a string) in the first row. Similarly, we move the cursor to (0, 1), i.e. the first position in the second row, and display the ‘value’ entry (a number). Finally, we pause the program for 2 seconds before showing the next entry.

You can get other data like real time stock quotes in the same way, and create things that are more exciting, such as stock market analysis with AI. Also, you can use other methods in the requests library to interact with other RESTful APIs. For instance, you can POST the data from a sensor attached to a Raspberry Pi to a Google Sheets spreadsheet via Google’s APIs. The possibility of this paradigm is only limited by our imagination.

This is a LCD display HAT for Raspberry Pi, 1.44inch diagonal, 128x128 pixels, with embedded controller, communicating via SPI interface. It also comes with three push button and a joystick, a good option as user interface panel for your Raspberry Pi Zero :)

This tutorial builds my first LCD display tutorial so I recommend you watch it first. I received a request to combine inputs with an LCD display so I made the following video for the Raspberry Pi that demonstrates polling switches connected to GPIO pins and interrupt callback functions:

Switches are easy to connect to the Raspberry Pi. One terminal of the switch is connected to ground and the other terminal is connected to any GPIO pin. A pull-up resistor is used on the GPIO side to insure the pin defaults to a high state when the switch is off. Activating the switch grounds the GPIO pin to a low state. The Python GPIO.input() method can read the state of the pin and will return true if the pin is high and false if the pin is low.

The Pi GPIO pins have internal pull-up resistors which can be activated when the pin is set up. Therefore,  you don’t have to add any external resistors as in the circuit above. The pins can also be configured with internal pull-down resistors which insures a default low state.

Make sure you launch Idle with super user privileges which is required to access the GPIO. (Update: super-user privileges are no longer required for GPIO access with the latest version of Raspbian.)The Idle IDE no longer comes with the latest version of Raspbian.  It has been replaced by the Thonny Python IDE.

The LCD display wiring differs from my first video as show below. You can use any 6 GPIO pins for RS, Enable and D4-D7. I usually select pins that will facilitate filming and programming. Also the pinouts of LCD displays can vary as well as the power requirements  for the backlight so please chec V without a resistor. Even if your display supports 5 V you might want to add a resistor or variable resistor to control the brightness. The same holds true for the contrast pin. I normally use variable resistors for both.

The wiring is different from my video and Adafruit has made breaking changes to the CharLCD library since the video.  Here is the updated code to declare an lcd:

My first example uses polling to check the state of a switch. The GPIO.setup() method sets GPIO pin 16 to an input and turns on the internal pull-up resistor. The GPIO.input() method in the main program loop reads the state of the pin connected to the switch every second and displays the results on an LCD display. A result of 1 indicates the pin is high and the button is not pressed. A zero indicates the pin is low and the button is pressed.

This is a very easy way to monitor a switch. The disadvantage is that there can be button lag or missed presses depending on the speed of the loop and the other code running. Faster loops produce better results but also use up more CPU resources. A better way to check a switch is with interrupts. This method interrupts the program when the state of GPIO pin changes and fires a callback function. The following code uses the GPIO.add_event_detect() method to add an interrupt on GPIO 16 that fires a method called buttonPressed as soon as the switch is released. This is a rising state because the switch is rising from 0 to 3.3 V. Notice that the main program loop is empty, because everything is handle by the interrupt and the callback.from Adafruit_CharLCD import Adafruit_CharLCD

I use a channel list to set up 17 inputs at once. There is a callback function toggleChanged() for the toggle switch. It needs to fire when the switch changes in both directions so the GPIO.BOTH parameter is passed during setup to catch falling and rising events. The function either displays the results or clears the display. There is another callback function keypadPressed() to handle the keypad button presses. A loop is used to generate the 16 keypad button interrupts.

some jokes (dark jokes preferably, because I"m a horrible human being) displayed from JokeApi. I basically copied the example script and started from there.

This CPU Info 1.6-inch LCD screen has a resolution of 84*48. Through the internal program of the Raspberry Pi, the CPU occupancy rate and memory occupancy rate running on the Raspberry Pi, the IP address of the Raspberry Pi, and the CPU temperature are displayed on the LCD screen.

Because of the 26Pin GPIO pin header compatible design, the LCD screen can be compatible with the whole series of Raspberry Pi motherboards of Pi0/Pil/Pi2/Pi3/Pi4 at the same time. After inserting the LCD screen into the Raspberry Pi motherboard, the occupied pins will still be drawn out on the LCD screen, which will not affect the secondary use.

The LCD screen is equipped with back light control. When the Raspberry Pi is used as a server, the operating status of the motherboard can be clearly seen at night. There is a back light jumper on the back, which can be controlled by a program.

Through programming, the LCD screen can be used to display numerical experiments, such as display ultrasonic distance measurement, temperature and humidity measurement and other experiments, and observe the experimental data in real time.

I finally freed up one of my breadboards. I got my semi-permanent temperature sensing interface fully up and running with the Pi Cobbler – logging to COSM.

The next thing I wanted to get working was a 16 x 2 LCD panel. (£6 from Tandy) Having seen other people get these working, I figured it couldn’t be all that hard and it wasn’t too bad actually. But I did make one small mistake along the way. I got it working the second time I tried it.

The mistake I made was trying to run it from a separate 5 Volt supply instead of directly from the Pi. I hadn’t connected it to the Pi’s earth, which I think is why it didn’t work first time round. Properly grounded, I think it would run from a separate supply (but don’t connect the +ves together or the regulators will have a fight).

There are 3V3 (3.3 Volt) versions of these LCDs available, but the 5V ones are more common. According to my flavour-of-the-month site, Adafruit, it’s safe enough to use a 5 Volt LCD with the Raspberry Pi as long as the read-write pin (pin 5) is connected to ground. As long as we only “write” to the screen and don’t try to take input from it (like you would on some embedded device with input buttons e.g. a battery charger).

That way, you won’t “send” a 5 Volt signal to the Pi’s GPIO (General Purpose Input Output) ports, which run on 3V3. Sending a 5 Volt signal to a 3V3 port would be very likely to toast the port. This is the basis of the instructions I followed…

…but I didn’t use the Pi Cobbler this time as it’s already in use with my semi-permanent temperature logging setup. Once I get that onto a permanent board, the Cobbler will be free again.

I’ve noticed a few times that this screen sometimes needs the scripts to be run a couple of times before it works properly. I don’t have an explanation for that. Once or twice it has displayed what looks like Japanese characters instead of Roman alpha-numerics.

Now this little LCD is displaying data pulled from my COSM temperature feed every 40 seconds. As I progressively add more sensors, I’ll be able to alternate the display, showing each set of readings for a few seconds before going on to the next. I’ve got plans for barometric pressure and light sensors already – who knows what else will crop up to occupy the remaining channels on the ADC? :rotfl: (Currently four channels available).