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Micropython LCD1602/LCD2004-I2C Lib

This is a micropython library for using LCD1602 or LCD2004 screen with PCF8574 I2C chip attached. It is modified from a module of micropython Chinese Community repository, with the added feature of creating custom characters and increased efficiency (by about 5~10 times faster for LCD2004 screen).

Usage

Hardware connection

  • Connect your micropython device as follow (my tests uses WEMOS LOLIN32 Lite):

    • PCF8574 I2C chip GND - ESP32 GND
    • PCF8574 I2C chip VCC - ESP32 +5V
    • PCF8574 I2C chip SCL - ESP32 GPIO pin 26 (pick your own pin, then modify the GPIO pin number in the code)
    • PCF8574 I2C chip SDA - ESP32 GPIO pin 27 (pick your own pin, then modify the GPIO pin number in the code)
    • If your PCF8574 and LCD scrren comes separately, solder the PCF8574 I2C chip to the screen per the manual.

  • Power-up your ESP32 board, adjust the contrast pot on the I2C chip until you see a line of solid blocks and an empty line.

  • Write your code, name it main.py.

  • Upload main.py and lib_lcd1602_2004_with_i2c.py to your board. Reboot.

Hello world

Call the LCD class with a Pin object of your SCL and SDA pin, then write character to the screen by using the .puts() method.

By default, .puts(string) writes to the left-top corner of the screen. You can designate the start position with .puts(string, row, column).

You need to write each line separately.

from machine import Pin, SoftI2C
from lib_lcd1602_2004_with_i2c import LCD
scl_pin = 26 # write your own pin number
sda_pin = 27 # write your own pin number
lcd = LCD(SoftI2C(scl=Pin(scl_pin), sda=Pin(sda_pin), freq=100000))
lcd.puts("Hello, World!")

lcd.puts("Hello, World!",1) will put the text in the second line.

lcd.puts("Hello, World!",2,4) will put the text in the third line, starts from the fifth column.

Custom character

A custom character is defined with a 5×8 binary matrix, for example:

custom_char = [
  0b00000,
  0b00000,
  0b00000,
  0b00000,
  0b00000,
  0b00000,
  0b00000,
  0b11111]

Then created with:

lcd.create_charactor(position,custom_char)

The position can only be between 0 and 7 (you can only create 8 custom characters). The new characters are treated as normal ASCII of 0x00~0x07. For example, if a custom character is created by calling lcd.create_charactor(5,custom_char), a normal python string containing chr(5) will be rendered with the character you just defined in position 5.

Once created, rendering custom characters requires the same time as any other standard ASCII character.

Example file main_Custom_Character_Example.py will produce an animation then render the following screen:

.

Here is another more practical example of using custom characters to show a bar-chart for multiple temperature and humidity probes on a LCD2004 screen.

.