A Python Library for Driving PCF8574 LCD Display Module

In the field of embedded development, LCD (Liquid Crystal Display) modules are commonly used output devices that help us visually display information. The PCF8574 is a commonly used I2C interface expansion chip that can drive LCDs. FaBoLCD_PCF8574 is a Python library that simplifies the process of driving the PCF8574 LCD display module in Python programs. This article will detail the installation, basic usage, advanced usage, and practical use cases of the FaBoLCD_PCF8574 library.

Installing the FaBoLCD_PCF8574 Library

First, you need to ensure that the pyserial library is installed in your Python environment, as the FaBoLCD_PCF8574 library depends on it. The following command installs the pyserial library in the Python environment:

pip install pyserial

Next, you can use the following command to install the FaBoLCD_PCF8574 library:

pip install fabolcd_pcf8574

Basic Usage

Initializing the LCD

Before using the FaBoLCD_PCF8574 library, you need to initialize the LCD. This typically includes setting the number of rows, columns, and I2C address of the LCD. Here is a simple initialization example:

from fabricio import LCD
# Create an LCD object, setting the number of rows, columns, and the I2C address
lcd = LCD(2, 16, 0x27)

In this example, we created a 2-row, 16-column LCD object, specifying the I2C address as 0x27.

Displaying Text

After initialization, you can use the write method to display text on the LCD. Here is an example:

# Display "Hello, World!" on the first line
lcd.write("Hello, World!", 0, 0)
# Display "LCD" on the second line
lcd.write("LCD", 1, 0)

Clearing the Screen

If you want to clear all content on the LCD, you can use the clear method:

# Clear the LCD screen
lcd.clear()

Advanced Usage

Setting Display Modes

The FaBoLCD_PCF8574 library provides options for setting display modes, including turning the display on/off and adjusting brightness. Here are some examples:

# Turn on the display
lcd.display_on()
# Turn off the display
lcd.display_off()
# Set brightness to maximum
lcd.set_backlight(15)
# Set brightness to minimum
lcd.set_backlight(0)

Setting Character Position

You can set the starting position of the text using the set_cursor method:

# Set the starting position of the text to the first row, first column
lcd.set_cursor(0, 0)
# Display text
lcd.write("New Position", 0, 0)

Practical Use Cases

Suppose you want to create a simple temperature monitor and use the FaBoLCD_PCF8574 library to display temperature information on the LCD. Here is a simple implementation example:

import time
from fabricio import LCD
import smbus
# Create an LCD object
lcd = LCD(2, 16, 0x27)
# Create an SMBus object
bus = smbus.SMBus(1)
# Temperature sensor I2C address
temp_sensor_address = 0x48
# Read temperature value
def read_temperature():
    # Read temperature sensor data
    bus.write_byte(temp_sensor_address, 0x00)
    time.sleep(0.5)
    data = bus.read_byte(temp_sensor_address)
    return data
# Main loop
while True:
    # Read temperature
    temp = read_temperature()
    # Display temperature
    lcd.write("Temp: {} C".format(temp), 0, 0)
    # Wait for a while before reading again
    time.sleep(1)

In this example, we use SMBus to read data from the temperature sensor and display it on the LCD.

Conclusion

The FaBoLCD_PCF8574 library is a very convenient Python library that can help you easily drive the PCF8574 LCD display module. Through this article, you should now understand how to install and use this library. I hope this library can help you achieve more projects.