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Raspberry Pi interfacing with 16×2 & 20×4 LCD

This tutorial will shows how to interfacing 16×2 and 20×2 LCD with Raspberry Pi. The code is written in Python language.

The 16×2 lcd has 16 pins, 16 characters and 2 lines and the 20×4 lcd has 16 pins, 20 characters and 4 lines.

Hardware to be used:

  • Raspberry PI 3B +
  • 16 GB SD Memory card with Raspbian operating system
  • 16×2 LCD 
  • 20×4 LCD
  • 20×2 FRC cable 9″
  • HDMI Monitor with HDMI Cable and Power Cable

Python Code for 16X2 lcd

#!/usr/bin/env python2
import RPi.GPIO as GPIO
from time import sleep
import time 
# Define GPIO to LCD mapping
LCD_RS = 27
LCD_E  = 17
LCD_D4 = 13
LCD_D5 = 19
LCD_D6 = 26
LCD_D7 = 6
# Define some device constants
LCD_WIDTH = 16    # Maximum characters per line
LCD_CHR = True
LCD_CMD = False
 
LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line
 
# Timing constants
E_PULSE = 0.003
E_DELAY = 0.0001
 
def main():
  # Main program block
  
  
	GPIO.setwarnings(False)
	GPIO.cleanup()
	GPIO.setmode(GPIO.BCM)       # Use BCM GPIO numbers
	GPIO.setup(LCD_E, GPIO.OUT)  # E
	GPIO.setup(LCD_RS, GPIO.OUT) # RS
	GPIO.setup(LCD_D4, GPIO.OUT) # DB4
	GPIO.setup(LCD_D5, GPIO.OUT) # DB5
	GPIO.setup(LCD_D6, GPIO.OUT) # DB6
	GPIO.setup(LCD_D7, GPIO.OUT) # DB7
	# Initialise display
	lcd_init()
 
	while True:
 
    # Send some test
		lcd_string("Sudarshan Systen",LCD_LINE_1)
		lcd_string("    Presents    ",LCD_LINE_2)
		sleep(3) # 3 second delay
		lcd_init()
		# Send some text
		lcd_string("Rasbperry Pi",LCD_LINE_1)
		lcd_string("16x2 LCD Test",LCD_LINE_2)
		sleep(3) # 3 second delay
		lcd_init()
		# Send some text
		lcd_string("1234567890*@$#%&",LCD_LINE_1)
		lcd_string("abcdefghijklmnop",LCD_LINE_2)
		sleep(3)
		lcd_init()
      
def lcd_init():
  lcd_display(0x28,LCD_CMD) # Selecting 4 - bit mode with two rows
  lcd_display(0x0C,LCD_CMD) # Display On,Cursor Off, Blink Off
  lcd_display(0x01,LCD_CMD) # Clear display
  sleep(E_DELAY)
 
def lcd_display(bits, mode):
  # Send byte to data pins
  # bits = data
  # mode = True  for character
  #        False for command
 
  GPIO.output(LCD_RS, mode) # RS
 
  # High bits
  GPIO.output(LCD_D4, False)
  GPIO.output(LCD_D5, False)
  GPIO.output(LCD_D6, False)
  GPIO.output(LCD_D7, False)
  if bits&0x10==0x10:
    GPIO.output(LCD_D4, True)
  if bits&0x20==0x20:
    GPIO.output(LCD_D5, True)
  if bits&0x40==0x40:
    GPIO.output(LCD_D6, True)
  if bits&0x80==0x80:
    GPIO.output(LCD_D7, True)
 
  # Toggle 'Enable' pin
  lcd_toggle_enable()
 
  # Low bits
  GPIO.output(LCD_D4, False)
  GPIO.output(LCD_D5, False)
  GPIO.output(LCD_D6, False)
  GPIO.output(LCD_D7, False)
  if bits&0x01==0x01:
    GPIO.output(LCD_D4, True)
  if bits&0x02==0x02:
    GPIO.output(LCD_D5, True)
  if bits&0x04==0x04:
    GPIO.output(LCD_D6, True)
  if bits&0x08==0x08:
    GPIO.output(LCD_D7, True)
 
  # Toggle 'Enable' pin
  lcd_toggle_enable()
 
def lcd_toggle_enable():
  # Toggle enable
  time.sleep(E_DELAY)
  GPIO.output(LCD_E, True)
  time.sleep(E_PULSE)
  GPIO.output(LCD_E, False)
  time.sleep(E_DELAY)
 
def lcd_string(message,line):
  # Send string to display
 
  message = message.ljust(LCD_WIDTH," ")
 
  lcd_display(line, LCD_CMD)
 
  for i in range(LCD_WIDTH):
    lcd_display(ord(message[i]),LCD_CHR)
 
if __name__ == '__main__':
 
  try:
    main()
  except KeyboardInterrupt:
    pass
  finally:
    lcd_display(0x01, LCD_CMD)
    GPIO.cleanup()

Python Code for 20X4 lcd

#!/usr/bin/python3
# The wiring for the LCD is as follows:
# 1 : GND
# 2 : 5V
# 3 : Contrast (0-5V)*
# 4 : RS (Register Select)
# 5 : R/W (Read Write)       - GROUND THIS PIN
# 6 : Enable or Strobe
# 7 : Data Bit 0             - NOT USED
# 8 : Data Bit 1             - NOT USED
# 9 : Data Bit 2             - NOT USED
# 10: Data Bit 3             - NOT USED
# 11: Data Bit 4
# 12: Data Bit 5
# 13: Data Bit 6
# 14: Data Bit 7
# 15: LCD Backlight +5V
# 16: LCD Backlight GND
 
#import
import RPi.GPIO as GPIO
import time
import curses
 
LCD_RS = 27
LCD_E  = 17
LCD_D4 = 13	
LCD_D5 = 19
LCD_D6 = 26
LCD_D7 = 6
LED_ON = 15
# Define some device constants
LCD_WIDTH = 20    # Maximum characters per line
LCD_CHR = True
LCD_CMD = False
 
LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line
LCD_LINE_3 = 0x94 # LCD RAM address for the 3rd line
LCD_LINE_4 = 0xD4 # LCD RAM address for the 4th line
 
# Timing constants
E_PULSE = 0.003
E_DELAY = 0.0001
DELAY   = 0
 
def main():
	
	# Main program block
	#GPIO.cleanup()
 
	#GPIO.setwarnings(False)
	#GPIO.cleanup()
	GPIO.setmode(GPIO.BCM)       # Use BCM GPIO numbers
	
	GPIO.setup(LCD_E, GPIO.OUT)  # E
	GPIO.setup(LCD_RS, GPIO.OUT) # RS
	GPIO.setup(LCD_D4, GPIO.OUT) # DB4
	GPIO.setup(LCD_D5, GPIO.OUT) # DB5
	GPIO.setup(LCD_D6, GPIO.OUT) # DB6
	GPIO.setup(LCD_D7, GPIO.OUT) # DB7
	#GPIO.setup(LED_ON, GPIO.OUT) # Backlight enable
	 
	# Initialise display
	lcd_init()
	
	#time.sleep(3) # 3 second delay
 
	lcd_string("--------------------",LCD_LINE_1,1)
	lcd_string("Rasbperry Pi",LCD_LINE_2,2)
	lcd_string("Model B",LCD_LINE_3,2)
	lcd_string("--------------------",LCD_LINE_4,2)
	 
	time.sleep(3) # 3 second delay
	lcd_byte(0x01,LCD_CMD) # 000001 Clear display
	lcd_string("SUDARSHAN SYSTEM",LCD_LINE_1,1)
	lcd_string("sudarshansystem.com",LCD_LINE_2,3)
	lcd_string("Its a time.",LCD_LINE_3,2)
	lcd_string("20x4 LCD Module Test",LCD_LINE_4,1)
	 
	time.sleep(20) # 20 second delay
	
	
def lcd_init():
	
	# Initialise display
	lcd_byte(0x33,LCD_CMD) # 110011 Initialise
	time.sleep(DELAY)
	lcd_byte(0x32,LCD_CMD) # 110010 Initialise
	time.sleep(DELAY)
	
	lcd_byte(0x06,LCD_CMD) # 000110 Cursor move direction
	time.sleep(DELAY)
	
	
	time.sleep(DELAY)
	
	lcd_byte(0x28,LCD_CMD) # 101000 Data length, number of lines, font size
	lcd_byte(0x0C,LCD_CMD) # 001100 Display On,Cursor Off, Blink Off
	lcd_byte(0x01,LCD_CMD) # 000001 Clear display
	
	
	time.sleep(DELAY)
	
	#lcd_byte(0x30,LCD_CMD) # 000001 Clear display
	#time.sleep(DELAY)
	
	#lcd_byte(0x28,LCD_CMD) # Selecting 4 - bit mode with two rows
	#lcd_byte(0x0C,LCD_CMD) # Display On,Cursor Off, Blink Off
	#lcd_byte(0x01,LCD_CMD) # Clear display
 
def lcd_byte(bits, mode):
	
	# Send byte to data pins
	# bits = data
	# mode = True  for character
	#        False for command
	GPIO.output(LCD_RS, mode) # RS
	# High bits
	GPIO.output(LCD_D4, False)
	GPIO.output(LCD_D5, False)
	GPIO.output(LCD_D6, False)
	GPIO.output(LCD_D7, False)
	if bits&0x10==0x10:
		
		GPIO.output(LCD_D4, True)
	if bits&0x20==0x20:
		GPIO.output(LCD_D5, True)
	if bits&0x40==0x40:
		GPIO.output(LCD_D6, True)
	if bits&0x80==0x80:
		GPIO.output(LCD_D7, True)
	
	
	# Toggle 'Enable' pin
	lcd_toggle_enable()
	# Low bits
	GPIO.output(LCD_D4, False)
	GPIO.output(LCD_D5, False)
	GPIO.output(LCD_D6, False)
	GPIO.output(LCD_D7, False)
	if bits&0x01==0x01:
		GPIO.output(LCD_D4, True)
	if bits&0x02==0x02:
		GPIO.output(LCD_D5, True)
	if bits&0x04==0x04:
		GPIO.output(LCD_D6, True)
	if bits&0x08==0x08:
		GPIO.output(LCD_D7, True)
	# Toggle 'Enable' pin
	lcd_toggle_enable()
 
def lcd_toggle_enable():
  # Toggle enable
  time.sleep(E_DELAY)
  GPIO.output(LCD_E, True)
  time.sleep(E_PULSE)
  GPIO.output(LCD_E, False)
  time.sleep(E_DELAY)
 
def lcd_string(message,line,style):
  # Send string to display
  # style=1 Left justified
  # style=2 Centred
  # style=3 Right justified
 
  if style==1:
    message = message.ljust(LCD_WIDTH," ")
  elif style==2:
    message = message.center(LCD_WIDTH," ")
  elif style==3:
    message = message.rjust(LCD_WIDTH," ")
 
  lcd_byte(line, LCD_CMD)
 
  for i in range(LCD_WIDTH):
    lcd_byte(ord(message[i]),LCD_CHR)
   
    
def lcd_backlight(flag):
  # Toggle backlight on-off-on
  GPIO.output(LED_ON, flag)
 
if __name__ == '__main__':
 
  try:
    main()
    print "Tushar"
  except KeyboardInterrupt:
    pass
  finally:
    lcd_byte(0x01, LCD_CMD)
    lcd_string("Goodbye!",LCD_LINE_1,2)
    GPIO.cleanup()
 
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