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Raspberry Pi 16×2 LCD I2C Interfacing and Python Programming– I have been using 16×2 LCD for quite a long time in different Arduino and IoT related projects. You know we have two types of the 16×2 LCD, the normal one used more wires and the other one is based on the I2C interface which needs only two wires.

The backpack module uses the I-squred-C (or I2C) protocol to communicate with the Raspberry Pi, which uses only two wires: SDA and SCL (data and clock). Please note that the display is a 5 volt device, and it is powered by 5 volts, but due to design of the I2C protocol, and the fact that the Raspberry Pi is the controlling device, it is safe to connect such display to the Raspberry Pi directly.

I suggest using wires of different colors to connect the LCD display. This minimizes the risk of damage due to incorrect connections. For example, I’m using

Before you start using the I2C 16×2 LCD display with Python, you need to make sure that the I2C protocol is enabled on your Raspberry Pi. You can use the sudo raspi-config utility to take care of that. This program is navigated using keyboard arrows, tab and the Enter key. Look for I2C in the interfacing options and enable it. Enabling I2C requires a reboot.

The 27 hexadecimal addresses happen to be the most common, but your display’s address may be different. For example, it could be 3f. This will depend on the chip version of the backpack module. As long as the i2cdetect command shows the display is connected, you are good to go.

The easiest way to program this 16×2 I2C LCD display in Python is by using a dedicated library. There are many to choose from. I like things simple, so the library I recommend is rpi_lcd.

This library has the default 27 address hard-coded. If your display has a different address you will need to change it. You need to find the library on your system and the following command should do that for you.

This repository contains all the code for interfacing with a 16x2 character I2C liquid-crystal display (LCD). This accompanies my Youtube tutorial: Raspberry Pi - Mini LCD Display Tutorial.

During the installation, pay attention to any messages about python and python3 usage, as they inform which version you should use to interface with the LCD driver. For example:

It is possible to define in CG RAM memory up to 8 custom characters. These characters can be prompted on LCD the same way as any characters from the characters table. Codes for the custom characters are unique and as follows:

This is demo showcases how extended strings could be used. Extended strings can contain special placeholders of form {0xFF}, that is, a hex code of the symbol wrapped within curly brackets. Hex codes of various symbols can be found in the following characters table:

For example, the hex code of the symbol ö is 0xEF, and so this symbol could be printed on the second row of the display by using the {0xEF} placeholder, as follows:

If you want to combine placeholder to write a symbol {0xFF} with the native Python placeholder {0} for inserting dome data into text, escape the non-native placeholders. Here is an example:

Once you are done editing a demo_*.py file or writing your own Python script, follow the instructions on this section to run the script in the background. First, however, ensure that the script (e.g., script.py) has at least permission to be executed, as follows:

An online editor for creating customer characters is available online at https://clach04.github.io/lcdchargen/ (source code available from https://github.com/clach04/lcdchargen/tree/python)

Once you’ve played with LEDs, switches and stepper motors the next natural step is 16×2 alphanumeric LCD modules. These modules are cheap (less than $10) and easy to interface to the Raspberry Pi. They have 16 connections but you only need to use 6 GPIO pins on your Pi.

Most of the 16×2 modules available are compatible with the Hitachi HD44780 LCD controller. This allows you to buy almost any device and be sure it is going to work in much the same way as any other. There are loads to choose from on eBay with different coloured backlights. The one I purchased had a blue backlight.

You can control a HD44780 style display using any programming environment you like but my weapon of choice is Python. I use the RPi.GPIO library to provide access to the GPIO.

This script can be downloaded using this link or directly to your Pi using the following command :wget https://bitbucket.org/MattHawkinsUK/rpispy-misc/raw/master/python/lcd_16x2.py

If you use this code the only thing you will need to change is the GPIO pin mapping depending on what pins you use on your Pi GPIO header. Here are some photos :

Additional Notes : RS is low when sending a command to the LCD and high when sending a character. RW is always low to ensure we only ever input data into the module. 8 bit bytes are sent 4 bits at a time. Top 4 bits first and the last 4 bits second. Delays are added between certain steps to ensure the module can react to the signal before it changes.

The code above was inspired by code submitted by ‘texy’ on the RaspberryPi.org forum. I changed the way the bytes are broken down to bits as this significantly increased the response time of the display.

Connecting an LCD to your Raspberry Pi will spice up almost any project, but what if your pins are tied up with connections to other modules? No problem, just connect your LCD with I2C, it only uses two pins (well, four if you count the ground and power).

In this tutorial, I’ll show you everything you need to set up an LCD using I2C, but if you want to learn more about I2C and the details of how it works, check out our article Basics of the I2C Communication Protocol.

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.

There are a couple ways to use I2C to connect an LCD to the Raspberry Pi. The simplest is to get an LCD with an I2C backpack. But the hardcore DIY way is to use a standard HD44780 LCD and connect it to the Pi via a chip called the PCF8574.

The PCF8574 converts the I2C signal sent from the Pi into a parallel signal that can be used by the LCD. Most I2C LCDs use the PCF8574 anyway. I’ll explain how to connect it both ways in a minute.

I’ll also show you how to program the LCD using Python, and provide examples for how to print and position the text, clear the screen, scroll text, print data from a sensor, print the date and time, and print the IP address of your Pi.

Connecting an LCD with an I2C backpack is pretty self-explanatory. Connect the SDA pin on the Pi to the SDA pin on the LCD, and the SCL pin on the Pi to the SCL pin on the LCD. The ground and Vcc pins will also need to be connected. Most LCDs can operate with 3.3V, but they’re meant to be run on 5V, so connect it to the 5V pin of the Pi if possible.

If you have an LCD without I2C and have a PCF8574 chip lying around, you can use it to connect your LCD with a little extra wiring. The PCF8574 is an 8 bit I/O expander which converts a parallel signal into I2C and vice-versa. The Raspberry Pi sends data to the PCF8574 via I2C. The PCF8574 then converts the I2C signal into a 4 bit parallel signal, which is relayed to the LCD.

Before we get into the programming, we need to make sure the I2C module is enabled on the Pi and install a couple tools that will make it easier to use I2C.

Now we need to install a program called I2C-tools, which will tell us the I2C address of the LCD when it’s connected to the Pi. So at the command prompt, enter sudo apt-get install i2c-tools.

Next we need to install SMBUS, which gives the Python library we’re going to use access to the I2C bus on the Pi. At the command prompt, enter sudo apt-get install python-smbus.

Now reboot the Pi and log in again. With your LCD connected, enter i2cdetect -y 1 at the command prompt. This will show you a table of addresses for each I2C device connected to your Pi:

We’ll be using Python to program the LCD, so if this is your first time writing/running a Python program, you may want to check out How to Write and Run a Python Program on the Raspberry Pi before proceeding.

I found a Python I2C library that has a good set of functions and works pretty well. This library was originally posted here, then expanded and improved by GitHub user DenisFromHR.

There are a couple things you may need to change in the code above, depending on your set up. On line 19 there is a function that defines the port for the I2C bus (I2CBUS = 0). Older Raspberry Pi’s used port 0, but newer models use port 1. So depending on which RPi model you have, you might need to change this from 0 to 1.

The function mylcd.lcd_display_string() prints text to the screen and also lets you chose where to position it. The function is used as mylcd.lcd_display_string("TEXT TO PRINT", ROW, COLUMN). For example, the following code prints “Hello World!” to row 2, column 3:

On a 16×2 LCD, the rows are numbered 1 – 2, while the columns are numbered 0 – 15. So to print “Hello World!” at the first column of the top row, you would use mylcd.lcd_display_string("Hello World!", 1, 0).

You can create any pattern you want and print it to the display as a custom character. Each character is an array of 5 x 8 pixels. Up to 8 custom characters can be defined and stored in the LCD’s memory. This custom character generator will help you create the bit array needed to define the characters in the LCD memory.

The code below will display data from a DHT11 temperature and humidity sensor. Follow this tutorial for instructions on how to set up the DHT11 on the Raspberry Pi. The DHT11 signal pin is connected to BCM pin 4 (physical pin 7 of the RPi).

By inserting the variable from your sensor into the mylcd.lcd_display_string() function (line 22 in the code above) you can print the sensor data just like any other text string.

These programs are just basic examples of ways you can control text on your LCD. Try changing things around and combining the code to get some interesting effects. For example, you can make some fun animations by scrolling with custom characters. Don’t have enough screen space to output all of your sensor data? Just print and clear each reading for a couple seconds in a loop.

Raspberry Pi is my hobby and I thought of sharing with you about these tiny projects. This will be a multi article series. Let us start with how to connect a I2C LCD display with the Raspberry Pi.

When you buy the LCD module, you can purchase LCD, I2C adapter separately and solder it. If soldering is not your thing, then it is better to buy the LCD module that comes with the I2C adapter backpack with it.

The above image is backside of a 2004 LCD module. The black thing is the I2C adapter. You can see the four pins GND, VCC, SDA and SCL. That’s where the you will be connecting the Raspberry Pi.

Raspberry Pi GPIO pins are natively of 3.3V. So we should not pull 5v from Raspberry Pi. The I2C LCD module works on 5V power and to make these compatible, we need to shift up the 3.3V GPIO to 5V. To do that, we can use a logic level converter.

You might see RPIs connected directly to a 5V devices, but they may not be pulling power from RPI instead supplying externally. Only for data / instruction RPI might be used. So watch out, you might end up frying the LCD module or the RPI itself.

As you know my language of choice to build website is PHP. But for IoT with Raspberry Pi, let us use Python. Reason being availability of packages and that will save ton of effort. Low level interactions via serial or parallel interface is easier via Python.

Following code imports the RPLCD library. Then initializes the LCD instance. Then print the “Hello World” string followed by new line. Then another two statements. Then a sleep for 5 seconds and switch off the LCD backlight. Finally, clear the LCD screen.

Raspberry Pi is my hobby and I thought of sharing with you about these tiny projects. This will be a multi article series. Let us start with how to connect a I2C LCD display with the Raspberry Pi.

When you buy the LCD module, you can purchase LCD, I2C adapter separately and solder it. If soldering is not your thing, then it is better to buy the LCD module that comes with the I2C adapter backpack with it.

The above image is backside of a 2004 LCD module. The black thing is the I2C adapter. You can see the four pins GND, VCC, SDA and SCL. That’s where the you will be connecting the Raspberry Pi.

Raspberry Pi GPIO pins are natively of 3.3V. So we should not pull 5v from Raspberry Pi. The I2C LCD module works on 5V power and to make these compatible, we need to shift up the 3.3V GPIO to 5V. To do that, we can use a logic level converter.

You might see RPIs connected directly to a 5V devices, but they may not be pulling power from RPI instead supplying externally. Only for data / instruction RPI might be used. So watch out, you might end up frying the LCD module or the RPI itself.

As you know my language of choice to build website is PHP. But for IoT with Raspberry Pi, let us use Python. Reason being availability of packages and that will save ton of effort. Low level interactions via serial or parallel interface is easier via Python.

Following code imports the RPLCD library. Then initializes the LCD instance. Then print the “Hello World” string followed by new line. Then another two statements. Then a sleep for 5 seconds and switch off the LCD backlight. Finally, clear the LCD screen.

If you plan on using an LCD with your Raspberry Pi, there’s a good chance you’ll need to program it in Python at some point. Python is probably the most popular programming language for coding on the Raspberry Pi, and many of the projects and examples you’ll find are written in Python.

In this tutorial, I’ll show you how to connect your LCD and program it in Python, using the RPLCD library. I’ll start with showing you how to connect it in either 8 bit mode or 4 bit mode. Then I’ll explain how to install the library, and provide examples for printing and positioning text, clearing the screen, and controlling the cursor. I’ll also give you examples for scrolling text, creating custom characters, printing data from a sensor, and displaying the date, time, and IP address of your Pi.

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.

You can also connect the LCD via I2C, which uses only two wires, but it requires some extra hardware. Check out our article, How to Setup an I2C LCD on the Raspberry Pi to see how.

There are two ways to connect the LCD to your Raspberry Pi – in 4 bit mode or 8 bit mode. 4 bit mode uses 6 GPIO pins, while 8 bit mode uses 10. Since it uses up less pins, 4 bit mode is the most common method, but I’ll explain how to set up and program the LCD both ways.

Each character and command is sent to the LCD as a byte (8 bits) of data. In 8 bit mode, the byte is sent all at once through 8 data wires, one bit per wire. In 4 bit mode, the byte is split into two sets of 4 bits – the upper bits and lower bits, which are sent one after the other over 4 data wires.

Theoretically, 8 bit mode transfers data about twice as fast as 4 bit mode, since the entire byte is sent all at once. However, the LCD driver takes a relatively long time to process the data, so no matter which mode is being used, we don’t really notice a difference in data transfer speed between 8 bit and 4 bit modes.

If this is your first time writing and running a Python program, you might want to read How to Write and Run a Python Program on the Raspberry Pi, which will explain everything you need to know to run the examples below.

The RPLCD library can be installed from the Python Package Index, or PIP. It might already be installed on your Pi, but if not, enter this at the command prompt to install it:

The example programs below use the Raspberry Pi’s physical pin numbers, not the BCM or GPIO numbers. I’m assuming you have your LCD connected the way it is in the diagrams above, but I’ll show you how to change the pin connections if you need to.

Let’s start with a simple program that will display “Hello world!” on the LCD. If you have a different sized LCD than the 16×2 I’m using (like a 20×4), change the number of columns and rows in line 2 of the code. cols= sets the number of columns, and rows= sets the number of rows. You can also change the pins used for the LCD’s RS, E, and data pins. The data pins are set as pins_data=[D0, D1, D2, D3, D4, D5, D6, D7].

The text can be positioned anywhere on the screen using lcd.cursor_pos = (ROW, COLUMN). The rows are numbered starting from zero, so the top row is row 0, and the bottom row is row 1. Similarly, the columns are numbered starting at zero, so for a 16×2 LCD the columns are numbered 0 to 15. For example, the code below places “Hello world!” starting at the bottom row, fourth column:

The RPLCD library provides several functions for controlling the cursor. You can have a block cursor, an underline cursor, or a blinking cursor. Use the following functions to set the cursor:

Text will automatically wrap to the next line if the length of the text is greater than the column length of your LCD. You can also control where the text string breaks to the next line by inserting \n\r where you want the break to occur. The code below will print “Hello” to the top row, and “world!” to the bottom row.

This program will print the IP address of your ethernet connection to the LCD. To print the IP of your WiFi connection, just change eth0 in line 19 to wlan0:

Each character on the LCD is an array of 5×8 of pixels. You can create any pattern or character you can think of, and display it on the screen as a custom character. Check out this website for an interactive tool that creates the bit array used to define custom characters.

First we define the character in lines 4 to 12 of the code below. Then we use the function lcd.create_char(0-7, NAME) to store the character in the LCD’s CGRAM memory. Up to 8 (0-7) characters can be stored at a time. To print the custom character, we use lcd.write_string(unichr(0)), where the number in unichr() is the memory location (0-7) defined in lcd.create_char().

In general, you take the input variable from your sensor and convert it to an integer to perform any calculations. Then convert the result to a string, and output the string to the display using lcd.write_string(sensor_data()):

Well, that about covers most of what you’ll need to get started programming your LCD with Python. Try combining the programs to get some interesting effects. You can display data from multiple sensors by printing and clearing the screen or positioning the text. You can also make fun animations by scrolling custom characters.

Pygame is a cross-platform set of Python modules designed for writing video games. It includes computer graphics and sound libraries designed to be used with the Python programming language. Now, it’s up to the imagination or necessity of the developer, what type of game he/she wants to develop using this toolkit.

This is all carried out with code. Display manufacturers usually supply some of these procedures/methods but leave the rest up to the end user to construct.

At the top of our driver program we will always import a minimal set of libraries using this block at the top of our MicroPython script (we add even more later when we want to do advanced programs):

The following methods draw shapes (such as those above) onto the FrameBuffer. They only become visible to the user once the lcd.show() instruction is executed.

Each program contains the screen driver code, sets up the buttons/joystick (if applicable), sets the width and height variables, loads the essential libraries, defines the colour (R, G, B) and clear (c) procedures, then displays some colour checking text like this:

Using lcd.fill_rect, fill the whole screen green and then fill the middle of the screen black, leaving a 10 pixel border. Put red 10-pixel squares in each corner.

This is routine is very complicated. It splits the original triangle into two with a horizontal line and then fills them in. If you uncomment all the # lcd.show() lines and sleep instructions it will slow right down and you can see it working (unfortunately, the 2” display needs such a large buffer that there is not enough memory for the filled triangles code):

For the imports we added the math library as this is needed for Sin and Cos in graph plotting. The random library has also been imported, for the randomly generated triangles. These are followed by the basic LCD board setup we covered earlier.

Start with the MIN program you saved earlier. Save it with the name Bar.py. Delete the main part of the program and paste in this code. It allows us to control a variable, v, in the range 0 to 100 with two buttons. You can also halt the program with the third button.

This article was written by Tony Goodhew. Tony is a retired teacher of computing who starting writing code back in 1968 when it was called programming - he started with FORTRAN IV on an IBM 1130! An active Raspberry Pi community member, his main interests now are coding in MicroPython, travelling and photography.

I"m working on some new projects involving getting stock price data from the web, which will be tracked and displayed via my Raspberry Pi. I wanted to share the setup on how to do this using Python.

pip is a package manager and installer for Python. We want to have this installed to get the appropriate Yahoo python stock libraries loaded onto the Pi.

ystockquote is a Python module that will let you easily gather stock quotes from Yahoo. It does this reasonably quickly, a lot more so than BeautifulSoup, which would be another way to get stock data.