Raspberry Pi 16×2 LCD I2C Interfacing and Python Programming

(Last Updated On: April 1, 2021)

Description:

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.

16×2 LCD with Arduino

16×2 LCD with Nodemcu ESP8266

Raspberry Pi 16x2 LCD

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Raspberry Pi

16X2 LCD

Wireless Keyboard and Mouse for raspberry pi:

Night vision Camera for Raspberry Pi:

Oled HDMI touch display for raspberry pi:

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Super Starter kit for Beginners

Digital Oscilloscopes

Variable Supply

Digital Multimeter

Soldering iron kits

PCB small portable drill machines

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This article will demonstrate how to use the I2C two-line LCD 16×2 display with the Raspberry Pi.

Specifically, I will be looking at the model that has the I2C backpack attached.

Raspberry Pi 16x2 LCD

If you have the plain version of this display then this tutorial is not for you. The plain version is not practical anyway  it would use a lot of GPIO Pins and it has a complicated programming requirement.

With this version you need only four pins and the programming model is very simple. Other than the display you will need some wires. This is what I will be using.

Raspberry Pi 16x2 LCD



The right-hand side matches the backpack pins, while the left hand-side will go to a breadboard. You also need a small Phillips screwdriver to adjust the contrast.

Raspberry Pi 16x2 LCD

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.

Raspberry Pi 16x2 LCD

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

Gray for GND,

Red for 5 volt,

Blue for SDA and

Green for SCL.

Raspberry Pi 16x2 LCD

I use the cobbler connector with a breadboard, but the display can be connected to the GPIO headers directly, you’ll just need to use different wires. 5 volts and ground connections are close to each other here, while the SDA and SCL line are connected on the opposite side.

Raspberry Pi 16x2 LCD


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.

Raspberry Pi 16x2 LCD

Raspberry Pi 16x2 LCD

Raspberry Pi 16x2 LCD

Once the system is back you can check whether the I2C bus is active, I2C protocol supports multiple devices connected to the same bus, and it identifies each device by their hardware address. The i2cdetect command can be used to see what is connected and what the addresses are.

Raspberry Pi 16x2 LCD

It’s time to connect the display and see whether it is recognized. Double-check your wires before making the connection!

The display is backlit

Raspberry Pi 16x2 LCD


And you can also adjust the contrast using a small Phillips screwdriver. Set it somewhere in the middle. Be careful not to short anything with the screwdriver while you make the adjustment. Looks like my display is ready to go.

Raspberry Pi 16x2 LCD

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.

Raspberry Pi 16x2 LCD

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.

Install the library using this command

sudo pip3 install 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.

sudo find /usr/local –name rpi_lcd 2> /dev/null

And press enter

This command will find the location of the library in my case my system location is

/usr/local/lib/python3.7/dist-packages/rpi_lcd

And you could go there and edit the library if needed.

Using the cd command

cd  /usr/local/lib/python3.7/dist-packages/rpi_lcd

You can use any text editor, for example nano, but make sure to run it as root using sudo. This is the spot where the change needs to be made.

Raspberry Pi 16x2 LCD


Lcd16x2 i2c display with raspberry pi code:

Time to write a test program!

With the rpi_lcd library the programming of the display is very easy just a couple of lines of code.

Program Explanation:

You need an import and an LCD object instance.

from rpi_lcd import LCD

lcd = LCD()

I will use two functions of this class:

lcd.text(“Hello,”, 1)

    lcd.text(“Raspberry Pi!”, 2)

the text function to write to the display, and clear function to erase it.

lcd.clear()

I use the clear function at the end of the program, otherwise the message will stay on the display after the program ends. The two numbers (1 and 2) at the end of the text function indicate which line of the display to use.

    lcd.text(“Hello,”, 1)

    lcd.text(“Raspberry Pi!”, 2)



This is an opportunity to adjust the contrast, especially if the display does not show anything, if you don’t see the “Hello, Raspberry Pi!” message. The adjustment only affects the letters, not the backlight. The backlight in this model is not adjustable, it’s always on, but you can turn it off by removing the jumper on the backpack.

Raspberry Pi 16x2 LCD

Testing:

Raspberry Pi 16x2 LCD

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About the Author: Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

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