#!/usr/bin/python
#--------------------------------------
# LCD Test Script
#
#--------------------------------------
# The wiring for the LCD is as follows:
# 1 : GND
# 2 : 5V
# 3 : Contrast (0-5V)* - Sets the LCD Contrast
# 4 : RS (Register Select) - GPIO pin 26 - Physical pin 37
# 5 : R/W (Read Write) - GROUND THIS PIN
# 6 : Enable or Strobe - GPIO pin 19 - Physical pin 35
# 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 - GPIO pin 13 - Physical pin 33
# 12: Data Bit 5 - GPIO pin 06 - Physical pin 31
# 13: Data Bit 6 - GPIO pin 05 - Physical pin 29
# 14: Data Bit 7 - GPIO pin 11 - Physical pin 23
# 15: LCD Backlight - +5V**
# 16: LCD Backlight - GND
#import
import RPi.GPIO as GPIO
import time
# Define GPIO to LCD mapping
LCD_RS = 26
LCD_E = 19
LCD_D4 = 13
LCD_D5 = 6
LCD_D6 = 5
LCD_D7 = 11
# Define some device constants
LCD_WIDTH = 40 # Maximum characters per line
LCD_CHR = True
LCD_CMD = False
# Do I need to change line 2 address for 40 char display?
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 = 0.0005
E_DELAY = 0.0005
def main():
# Main program block
GPIO.setwarnings(False)
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("Rasbperry Pi",LCD_LINE_1)
lcd_string("40x2 LCD Test",LCD_LINE_2)
time.sleep(3) # 3 second delay
# Send some text
lcd_string("Another Example :)",LCD_LINE_1)
lcd_string("Now do your own",LCD_LINE_2)
time.sleep(3)
def lcd_init():
# Initialise display
lcd_byte(0x33,LCD_CMD) # 110011 Initialise
lcd_byte(0x32,LCD_CMD) # 110010 Initialise
lcd_byte(0x06,LCD_CMD) # 000110 Cursor move direction
lcd_byte(0x0C,LCD_CMD) # 001100 Display On,Cursor Off, Blink Off
lcd_byte(0x28,LCD_CMD) # 101000 Data length, number of lines, font size
lcd_byte(0x01,LCD_CMD) # 000001 Clear display
time.sleep(E_DELAY)
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):
# Send string to display
message = message.ljust(LCD_WIDTH," ")
lcd_byte(line, LCD_CMD)
for i in range(LCD_WIDTH):
lcd_byte(ord(message[i]),LCD_CHR)
if __name__ == '__main__':
try:
main()
except KeyboardInterrupt:
pass
finally:
lcd_byte(0x01, LCD_CMD)
lcd_string("Goodbye!",LCD_LINE_1)
GPIO.cleanup()