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3.4 Liquid Crystal Display

LCD1602 is a character type liquid crystal display, which can display 32 (16*2) characters at the same time.

As we all know, though LCD and some other displays greatly enrich the man-machine interaction, they share a common weakness. When they are connected to a controller, multiple IOs will be occupied of the controller which has no so many outer ports. Also it restricts other functions of the controller. Therefore, LCD1602 with an I2C bus is developed to solve the problem.

pin_i2c

Here we will use the I2C0 interface to control the LCD1602 and display text.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Kepler Kit

450+

Kepler Ultimate Kit

You can also buy them separately from the links below.

SN

COMPONENT

QUANTITY

LINK

1

Raspberry Pi Pico W

1

BUY

2

Micro USB Cable

1

3

Breadboard

1

BUY

4

Jumper Wires

Several

BUY

5

I2C LCD1602

1

BUY

Schematic

sch_lcd

Wiring

wiring_lcd

Code

Note

  • Open the 3.4_liquid_crystal_display.py file under the path of kepler-kit-main/micropython or copy this code into Thonny, then click “Run Current Script” or simply press F5 to run it.

  • Don’t forget to click on the “MicroPython (Raspberry Pi Pico)” interpreter in the bottom right corner.

  • For detailed tutorials, please refer to Open and Run Code Directly.

  • Here you need to use the library called lcd1602.py, please check if it has been uploaded to Pico W, for a detailed tutorial refer to 1.4 Upload the Libraries to Pico.

from machine import I2C, Pin
from lcd1602 import LCD
import time

# Initialize I2C communication;
i2c = I2C(1, sda=Pin(6), scl=Pin(7), freq=400000)

# Create an LCD object for interfacing with the LCD1602 display
lcd = LCD(i2c)

# Display the first message on the LCD
# Use '\n' to create a new line.
string = "SunFounder\n    LCD Tutorial"
lcd.message(string)
# Wait for 2 seconds
time.sleep(2)
# Clear the display
lcd.clear()

# Display the second message on the LCD
string = "Hello\n  World!"
lcd.message(string)
# Wait for 5 seconds
time.sleep(5)
# Clear the display before exiting
lcd.clear()

After the program runs, you will be able to see two lines of text appear on the LCD in turn, and then disappear.

Note

When the code is running, if the screen is blank, you can turn the potentiometer on the back to increase the contrast.

How it works?

  1. Setting up I2C Communication

    The machine module is used to set up I2C communication. SDA (Serial Data) and SCL (Serial Clock) pins are defined (pin 20 and 21 respectively), along with the I2C frequency (400kHz).

    from machine import I2C, Pin
    i2c = I2C(1, sda=Pin(6), scl=Pin(7), freq=400000)
    
  2. Initializing the LCD Display

    The LCD class from the lcd1602 module is instantiated. This class handles the communication with the LCD display through I2C. An LCD object is created using the i2c object.

    For more usage of the lcd1602 library, please refer to lcd1602.py.

    from lcd1602 import LCD
    lcd = LCD(i2c)
    
  3. Displaying Messages on the LCD

    The message method of the LCD object is used to display text on the screen. The \n character creates a new line on the LCD. The time.sleep() function pauses execution for a specified number of seconds.

    string = "SunFounder\n    LCD Tutorial"
    lcd.message(string)
    time.sleep(2)
    lcd.clear()
    
  4. Clearing the Display

    The clear method of the LCD object is called to clear the text from the display.

    lcd.clear()
    
  5. Displaying a Second Message

    A new message is displayed, followed by a delay and then clearing the screen again.

    string = "Hello\n  World!"
    lcd.message(string)
    time.sleep(5)
    lcd.clear()