lcd1602gpio 0.1.1

Use HD44780-compatible 16x2 LCD module via RPi.GPIO

lcd1602gpio

Use HD44780-compatible 16x2 LCD module by Python via Raspberry Pi GPIO

Introduction

Based on RPi.GPIO, it writes instructions to a 16x2 LCD module through Raspberry Pi's GPIO pins directly.

This is not for interfacing an I2C LCD.

This module provides the following functions:

• Initialize LCD in 8-bit and 4-bit data bus modes.
• Write instructions to LCD.
• Write data to LCD's DDRAM. (Data Display RAM)
• Write a line of string and display it on LCD.
• Clear LCD display.

This module cannot:

• Read any data or address from LCD.
• Any other HD44780-supported operations with writing to LCD involved. (e.g. Write to CGRAM, etc.)

Synopsis

class LCD1602GPIO
|   LCD1602GPIO(rs, e,
|               db7, db6, db5, db4,
|               db3, db2, db1, db0,
|               e_pulse=0.0005,
|               e_delay=0.0005,
|               delayfunc=time.sleep,
|               dl_mode=DL_8BIT) --> an LCD controller instance

Caveats

• Since it's not for realtime applications, the clock pulse and delays are not precise. This might not work with your LCD module properly or require some tweaks on delays. Using LCD module on an Arduino will make your life easier.
• Read function is not yet implemented so it does not read Busy Flag (BF) and the default value of delay is much longer to ensure each LCD instruction can be executed in time. The performance of manipulating an LCD module will be slower than expected.

Examples

The examples are based on LCD module LMM84S019D2E (PCB: M019F REV:A) manufactured by Nan Ya Plastics, but its pin layout may be different to yours. You may need to change the wiring and adjust the delay times if the LCD doesn't work.

It supports both 8-bit and 4-bit data bus modes. The R/W pin is grounded because read function is not yet implemented.

8-bit mode

The configuration requires 5V power, GND, 2 GPIO pins for signaling and 8 GPIO pins for 8-bit data bus.

No. of LCD Pin	Name	Description	RPi Pin
16	K	LCD Backlight Cathode	GND
15	A	LCD Backlight Anode	5V
1	GND	Ground	GND
2	+5V	+5V Power Supply	5V
3	Contrast	LCD Display Contrast	GND
4	RS	Register Select	GPIO 7
5	R/W	Read/Write Switch	GND
6	E	Enable Signal	GPIO 8
7	DB0	Data Bus	GPIO 26
8	DB1	Data Bus	GPIO 19
9	DB2	Data Bus	GPIO 13
10	DB3	Data Bus	GPIO 6
11	DB4	Data Bus	GPIO 25
12	DB5	Data Bus	GPIO 24
13	DB6	Data Bus	GPIO 23
14	DB7	Data Bus	GPIO 18

Import required Python modules and create an instance of LCD1602GPIO.

import RPi.GPIO as GPIO
import lcd1602gpio

# Disable GPIO warnings
GPIO.setwarnings(False)
# Set GPIO pin mode. RPi pins described in this example use BCM.
GPIO.setmode(GPIO.BCM)

# create an instance of LCD1602GPIO with 8-bit mode.
# the LCD module must be already powered on here.
# the instance initializes the LCD module immediately during init.
lcd = lcd1602gpio.LCD1602GPIO(
        rs=7,
        e=8,
        db7=18,
        db6=23,
        db5=24,
        db4=25,
        db3=6,
        db2=13,
        db1=19,
        db0=26)

# write texts to Line 0 of the LCD.
lcd.write_line("abcdefghijklmnop", 0)
# write texts to Line 1 of the LCD.
lcd.write_line("1234567890123456", 1)

# Do GPIO cleanup manually before exiting.
GPIO.cleanup()

4-bit mode

The configuration requires 5V power, GND, 2 GPIO pins for signaling and 4 GPIO pins for 4-bit data bus.

Those 4 low order data bus pins DB0 to DB3 are unconnected.

No. of LCD Pin	Name	Description	RPi Pin
16	K	LCD Backlight Cathode	GND
15	A	LCD Backlight Anode	5V
1	GND	Ground	GND
2	+5V	+5V Power Supply	5V
3	Contrast	LCD Display Contrast	GND
4	RS	Register Select	GPIO 7
5	R/W	Read/Write Switch	GND
6	E	Enable Signal	GPIO 8
7	DB0	Data Bus (Unused)	(None)
8	DB1	Data Bus (Unused)	(None)
9	DB2	Data Bus (Unused)	(None)
10	DB3	Data Bus (Unused)	(None)
11	DB4	Data Bus	GPIO 25
12	DB5	Data Bus	GPIO 24
13	DB6	Data Bus	GPIO 23
14	DB7	Data Bus	GPIO 18

Import required Python modules and create an instance of LCD1602GPIO.

import RPi.GPIO as GPIO
import lcd1602gpio

# Disable GPIO warnings
GPIO.setwarnings(False)
# Set GPIO pin mode. RPi pins described in this example use BCM.
GPIO.setmode(GPIO.BCM)

# create an instance of LCD1602GPIO with 4-bit mode.
# the LCD module must be already powered on here.
# the instance initializes the LCD module immediately during init.
lcd = lcd1602gpio.LCD1602GPIO(
        rs=7,
        e=8,
        db7=18,
        db6=23,
        db5=24,
        db4=25,
        db3=None,
        db2=None,
        db1=None,
        db0=None,
        dl_mode=lcd1602gpio.DL_4BIT)

# write texts to Line 0 of the LCD.
lcd.write_line("abcdefghijklmnop", 0)
# write texts to Line 1 of the LCD.
lcd.write_line("1234567890123456", 1)

# Do GPIO cleanup manually before exiting.
GPIO.cleanup()

Reference

• HD44780U (LCD-II), (Dot Matrix Liquid Crystal Display Controller/Driver) manual