lcd module python code factory

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.

lcd module python code factory

Business objects will be needed in many places within a project. Therefore, code snippets or constructors that create the related objects will be recalled throughout the system. For this reason, there will be a lot of copy-paste repetitions.

lcd module python code factory

This example illustrates how the Factory Method can be used for creating cross-platform UI elements without coupling the client code to concrete UI classes.

When the factory method comes into play, you don’t need to rewrite the logic of the Dialog class for each operating system. If we declare a factory method that produces buttons inside the base Dialog class, we can later create a subclass that returns Windows-styled buttons from the factory method. The subclass then inherits most of the code from the base class, but, thanks to the factory method, can render Windows-looking buttons on the screen.

For this pattern to work, the base Dialog class must work with abstract buttons: a base class or an interface that all concrete buttons follow. This way the code within Dialog remains functional, whichever type of buttons it works with.

lcd module python code factory

Class to display text on a LCD character display. The class supports the PCF8574T 8-bit I2C port expander connected to a HD44780 based LCD display. These displays are commonly available in 16x2 and 20x4 character formats.

This example shows how to use Kivy to control a Pi"s GPIO. The GPIO may be configured as inputs, outputs, or to generate Servo or PWM pulses. Kivy is an Open source Python library for rapid development of applications.

You can also specify one of py, c, or pdif - the script output will then be a complete program to generate the wave (py for Python script, c for a C program, pdif for a C program using the pigpio daemon I/F).

lcd module python code factory

Once you have installed the ADB tool, you need to get the python library which we will use to interface with the ADB and our device. You can install the pure-python-adb library using pip install pure-python-adb.

In our main code, we can call the connect function to retrieve the device and client objects. From there we can open up the camera app, wait 5 seconds and take a photo. It’s really that simple! As I said before, this is simply replicating what you would usually do, so thinking about how to do things is best if you do them yourself manually first and write down the steps.

lcd module python code factory

It’s a piece of great news! but what about the software developers of your startup. They have to change the whole code because now most part of the code is coupled with the Two-Wheeler class and developers have to make changes to the entire codebase.

It’s a piece of great news! only for the owner not for the developers. They have to change the whole code because now most part of the code is coupled with the existing languages only and that’s why developers have to make changes to the entire codebase which is really a difficult task to do.

You end up with a huge number of small files i.e, cluttering the files.In a Graphics system, depending upon the user’s input it can draw different shapes like rectangles, Square, Circle, etc. But for the ease of both developers as well as the client, we can use the factory method to create the instance depending upon the user’s input. Then we don’t have to change the client code for adding a new shape.

On a Hotel booking site, we can book a slot for 1 room, 2 rooms, 3 rooms, etc. Here user can input the number of rooms he wants to book. Using the factory method, we can create a factory class Any Rooms which will help us to create the instance depending upon the user’s input. Again we don’t have to change the client’s code for adding the new facility.