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#!/usr/bin/python # # HD44780 LCD Test Script for # Raspberry Pi # # Author : Matt Hawkins # Site : http://www.raspberrypi-spy.co.uk # # Date : 03/08/2012 #
# 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
# Define GPIO to LCD mapping LCD_RS = 26 LCD_E = 19 LCD_D4 = 13 LCD_D5 = 6 LCD_D6 = 5 LCD_D7 = 11 LED_ON = 15
# 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 = 0.00005 E_DELAY = 0.00005
def main():
# Main program block
# Initialise display lcd_init()
# Toggle backlight on-off-on GPIO.output(LED_ON, True) time.sleep(1) GPIO.output(LED_ON, False) time.sleep(1) GPIO.output(LED_ON, True) time.sleep(1)
# Send some centred test
lcd_byte(LCD_LINE_1, LCD_CMD)
lcd_string("Rasbperry Pi",2)
lcd_byte(LCD_LINE_2, LCD_CMD)
lcd_string("Model B",2)
time.sleep(3) # 3 second delay
# Send some left justified text
lcd_byte(LCD_LINE_1, LCD_CMD)
lcd_string("1234567890123456",1)
lcd_byte(LCD_LINE_2, LCD_CMD)
lcd_string("abcdefghijklmnop",1)
time.sleep(3) # 3 second delay
# Send some right justified text
lcd_byte(LCD_LINE_1, LCD_CMD)
lcd_string("Raspberrypi-spy",3)
lcd_byte(LCD_LINE_2, LCD_CMD)
lcd_string(".co.uk",3)
time.sleep(30)
# Turn off backlight GPIO.output(LED_ON, False)
def lcd_init():
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_byte(0x33,LCD_CMD) lcd_byte(0x32,LCD_CMD) lcd_byte(0x28,LCD_CMD) lcd_byte(0x0C,LCD_CMD) lcd_byte(0x06,LCD_CMD) lcd_byte(0x01,LCD_CMD)
def lcd_string(message,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," ")
for i in range(LCD_WIDTH): lcd_byte(ord(message[i]),LCD_CHR)
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 time.sleep(E_DELAY) GPIO.output(LCD_E, True) time.sleep(E_PULSE) GPIO.output(LCD_E, False) time.sleep(E_DELAY)
# 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 time.sleep(E_DELAY) GPIO.output(LCD_E, True) time.sleep(E_PULSE) GPIO.output(LCD_E, False) time.sleep(E_DELAY)
if name == 'main':
main()