lcddriver.py

#!/usr/bin/python

#
# LCD Support using I2C
#

import sys
import i2c_lib
from time import *

# LCD Address
ADDRESS = 0x27

# commands
LCD_CLEARDISPLAY = 0x01
LCD_RETURNHOME = 0x02
LCD_ENTRYMODESET = 0x04
LCD_DISPLAYCONTROL = 0x08
LCD_CURSORSHIFT = 0x10
LCD_FUNCTIONSET = 0x20
LCD_SETCGRAMADDR = 0x40
LCD_SETDDRAMADDR = 0x80

# flags for display entry mode
LCD_ENTRYRIGHT = 0x00
LCD_ENTRYLEFT = 0x02
LCD_ENTRYSHIFTINCREMENT = 0x01
LCD_ENTRYSHIFTDECREMENT = 0x00

# flags for display on/off control
LCD_DISPLAYON = 0x04
LCD_DISPLAYOFF = 0x00
LCD_CURSORON = 0x02
LCD_CURSOROFF = 0x00
LCD_BLINKON = 0x01
LCD_BLINKOFF = 0x00

# flags for display/cursor shift
LCD_DISPLAYMOVE = 0x08
LCD_CURSORMOVE = 0x00
LCD_MOVERIGHT = 0x04
LCD_MOVELEFT = 0x00

# flags for function set
LCD_8BITMODE = 0x10
LCD_4BITMODE = 0x00
LCD_2LINE = 0x08
LCD_1LINE = 0x00
LCD_5x10DOTS = 0x04
LCD_5x8DOTS = 0x00

# flags for backlight control
LCD_BACKLIGHT = 0x08
LCD_NOBACKLIGHT = 0x00

En = 0b00000100 # Enable bit
Rw = 0b00000010 # Read/Write bit
Rs = 0b00000001 # Register select bit

# For the case that we like to generate our own capital Umlaute
Auml = ( 0b01010,
		 0b00000,
		 0b01110,
		 0b10001,
		 0b10001,
		 0b11111,
		 0b10001,
		 0b10001 )

Ouml = ( 0b01010,
		 0b00000,
		 0b01110,
		 0b10001,
		 0b10001,
		 0b10001,
		 0b10001,
		 0b01110 )

Uuml = ( 0b01010,
		 0b00000,
		 0b10001,
		 0b10001,
		 0b10001,
		 0b10001,
		 0b10001,
		 0b01110 )

def convert_umlaute(arg):
	sw = {
		228: 225, # ä
		246: 239, # ö
		252: 245, # ü
		223: 226, # ß
		196: 0,   # 225, # Ä
		214: 1,   # 239, # Ö
		220: 2,   # 245, # Ü
		176: 223, # °
	}
	return sw.get(arg, arg)
 
class lcd:
	""" Initializes objects and lcd """
	def __init__(self):
		self.lcd_device = i2c_lib.i2c_device(ADDRESS)

		self.lcd_write(0x03)
		self.lcd_write(0x03)
		self.lcd_write(0x03)
		self.lcd_write(0x02)

		self.lcd_write(LCD_FUNCTIONSET | LCD_2LINE | LCD_5x8DOTS | LCD_4BITMODE)
		self.lcd_write(LCD_DISPLAYCONTROL | LCD_DISPLAYON)
		self.lcd_write(LCD_CLEARDISPLAY)
		self.lcd_write(LCD_ENTRYMODESET | LCD_ENTRYLEFT)
		sleep(0.2)
		
		self.lcd_create_umlaute()

	def lcd_create_umlaute(self):
		self.lcd_create_char(0, Auml)
		self.lcd_create_char(1, Ouml)
		self.lcd_create_char(2, Uuml)

	# clocks EN to latch command
	def lcd_strobe(self, data):
		self.lcd_device.write_cmd(data | En | LCD_BACKLIGHT)
		sleep(.0005)
		self.lcd_device.write_cmd(((data & ~En) | LCD_BACKLIGHT))
		sleep(.0001)

	def lcd_write_four_bits(self, data):
		self.lcd_device.write_cmd(data | LCD_BACKLIGHT)
		self.lcd_strobe(data)

	# write a command to lcd
	def lcd_write(self, cmd, mode=0):
		self.lcd_write_four_bits(mode | (cmd & 0xF0))
		self.lcd_write_four_bits(mode | ((cmd << 4) & 0xF0))
      
	# turn on/off the lcd backlight
	def lcd_backlight(self, state):
		if state in ("on","On","ON"):
			self.lcd_device.write_cmd(LCD_BACKLIGHT)
		elif state in ("off","Off","OFF"):
			self.lcd_device.write_cmd(LCD_NOBACKLIGHT)
		else:
			print "Unknown State!"

	def lcd_create_char(self, location, charmap):
		location &= 0x7
		self.lcd_write(LCD_SETCGRAMADDR | (location << 3))
		for i in range(8):
			self.lcd_write(charmap[i], Rs)

	# put string function
	def lcd_display_string(self, string, line):
		if line == 1:
			self.lcd_write(0x80)
		if line == 2:
			self.lcd_write(0xC0)
		if line == 3:
			self.lcd_write(0x94)
		if line == 4:
			self.lcd_write(0xD4)
	
		for char in string.decode("utf-8"):
			char = chr(convert_umlaute(ord(char)))
			self.lcd_write(ord(char), Rs)

	def message(self, string, line):
		if line == 1:
			self.lcd_write(0x80)
		if line == 2:
			self.lcd_write(0xC0)
		if line == 3:
			self.lcd_write(0x94)
		if line == 4:
			self.lcd_write(0xD4)
	
		for char in string:
			self.lcd_write(ord(char), Rs)

	# clear lcd and set to home
	def lcd_clear(self):
		self.lcd_write(LCD_CLEARDISPLAY)
		self.lcd_write(LCD_RETURNHOME)