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()