#!/usr/bin/python

# modified version if this tutorial's demo script (German):
# http://www.schnatterente.net/technik/raspberry-pi-32-zeichen-hitachi-hd44780-display

import time
import sys
import RPi.GPIO as GPIO
GPIO.setwarnings(False)

# Zuordnung der GPIO Pins (ggf. anpassen)
DISPLAY_RS = 7
DISPLAY_E  = 8
DISPLAY_DATA4 = 25 
DISPLAY_DATA5 = 24
DISPLAY_DATA6 = 23
DISPLAY_DATA7 = 18

DISPLAY_WIDTH = 16 	# Zeichen je Zeile (colums per line)
DISPLAY_LINE_1 = 0x80 	# Adresse der ersten Display Zeile
DISPLAY_LINE_2 = 0xC0

DISPLAY_CHR = True
DISPLAY_CMD = False
E_PULSE = 0.0005
E_DELAY = 0.0005

def main():
	GPIO.setmode(GPIO.BCM)
	GPIO.setup(DISPLAY_E, GPIO.OUT)
	GPIO.setup(DISPLAY_RS, GPIO.OUT)
	GPIO.setup(DISPLAY_DATA4, GPIO.OUT)
	GPIO.setup(DISPLAY_DATA5, GPIO.OUT)
	GPIO.setup(DISPLAY_DATA6, GPIO.OUT)
	GPIO.setup(DISPLAY_DATA7, GPIO.OUT)

	display_init()

	# my screen is internally wired as a 2x8, so that's that bodge. 
	if len (sys.argv) > 1:
		mystring = sys.argv[1].ljust (8, " ")
		lcd_byte (DISPLAY_LINE_1, DISPLAY_CMD)
		lcd_string (mystring[0:8])
		lcd_byte (DISPLAY_LINE_2, DISPLAY_CMD)
		lcd_string (mystring[8:16])


def display_init():
	lcd_byte(0x33,DISPLAY_CMD)
	lcd_byte(0x32,DISPLAY_CMD)
	lcd_byte(0x28,DISPLAY_CMD)
	lcd_byte(0x0C,DISPLAY_CMD)  
	lcd_byte(0x06,DISPLAY_CMD)
	lcd_byte(0x01,DISPLAY_CMD)  

def lcd_string(message):
	message = message.ljust(DISPLAY_WIDTH," ")  
	for i in range(DISPLAY_WIDTH):
	  lcd_byte(ord(message[i]),DISPLAY_CHR)

def lcd_byte(bits, mode):
	GPIO.output(DISPLAY_RS, mode)
	GPIO.output(DISPLAY_DATA4, False)
	GPIO.output(DISPLAY_DATA5, False)
	GPIO.output(DISPLAY_DATA6, False)
	GPIO.output(DISPLAY_DATA7, False)
	if bits&0x10==0x10:
	  GPIO.output(DISPLAY_DATA4, True)
	if bits&0x20==0x20:
	  GPIO.output(DISPLAY_DATA5, True)
	if bits&0x40==0x40:
	  GPIO.output(DISPLAY_DATA6, True)
	if bits&0x80==0x80:
	  GPIO.output(DISPLAY_DATA7, True)
	time.sleep(E_DELAY)    
	GPIO.output(DISPLAY_E, True)  
	time.sleep(E_PULSE)
	GPIO.output(DISPLAY_E, False)  
	time.sleep(E_DELAY)      
	GPIO.output(DISPLAY_DATA4, False)
	GPIO.output(DISPLAY_DATA5, False)
	GPIO.output(DISPLAY_DATA6, False)
	GPIO.output(DISPLAY_DATA7, False)
	if bits&0x01==0x01:
	  GPIO.output(DISPLAY_DATA4, True)
	if bits&0x02==0x02:
	  GPIO.output(DISPLAY_DATA5, True)
	if bits&0x04==0x04:
	  GPIO.output(DISPLAY_DATA6, True)
	if bits&0x08==0x08:
	  GPIO.output(DISPLAY_DATA7, True)
	time.sleep(E_DELAY)    
	GPIO.output(DISPLAY_E, True)  
	time.sleep(E_PULSE)
	GPIO.output(DISPLAY_E, False)  
	time.sleep(E_DELAY)   

if __name__ == '__main__':
	main()