I2C LCD 1602 driver for raspberry pi

pylcdlib.py

#!/usr/bin/env python
"""
original from http://www.rpiblog.com/2012/07/interfacing-16x2-lcd-with-raspberry-pi.html
I modified it, thus you can set customized pin defines, such as

   lcd(0x27,1, Rs=0, Rw=1, En=2, Backlight=3, D4=4, D5=5, D6=6, D7=7)
   
   address 0x27
   port    1
   
   P0 - Rs
   P1 - RW
   P2 - En
   P3 - Backlight
   P4-P7 - D4-D7

"""
import smbus
from time import  *

#  General  i2c  device  class  so  that  other  devices  can  be  added  easily
class i2c_device:
  def __init__(self, addr, port):
    self.addr = addr
    self.bus = smbus.SMBus(port)

  def write(self, byte):
    self.bus.write_byte(self.addr, byte)

  def read(self):
    return self.bus.read_byte(self.addr)

  def read_nbytes_data(self, data, n):  #  For  sequential  reads  >  1  byte
    return self.bus.read_i2c_block_data(self.addr,  data,  n)


class  lcd:
  #initializes  objects  and  lcd
  def  __init__(self, addr, port, **kwarg):
    self.pin = {}
    self.lcd_device = i2c_device(addr, port)
    self.config(**kwarg)
    self.Backlight = True
    self.low_level_write(En=False, Rs=False, Rw=False, data=3)
    self.lcd_strobe()
    sleep(0.0005)
    self.lcd_strobe()
    sleep(0.0005)
    self.lcd_strobe()
    sleep(0.0005)
    self.low_level_write(En=False, Rs=False, Rw=False, data=2)
    self.lcd_strobe()
    sleep(0.0005)

    self.lcd_write(0x28)
    self.lcd_write(0x08)
    self.lcd_write(0x01)
    self.lcd_write(0x06)
    self.lcd_write(0x0C)
    self.lcd_write(0x0F)

  def config(self, **kwarg):
    self.pin['Rs'] = kwarg.get('Rs', 4)
    self.pin['Rw'] = kwarg.get('Rw', 5)
    self.pin['En'] = kwarg.get('En', 6)
    self.pin['Backlight'] = kwarg.get('Backlight', 7)
    self.pin['D4'] = kwarg.get('D4', 0)
    self.pin['D5'] = kwarg.get('D5', 1)
    self.pin['D6'] = kwarg.get('D6', 2)
    self.pin['D7'] = kwarg.get('D7', 3)

  def backlight(self, on=True):
    self.backlight = on

  def low_level_write(self, En, Rs, Rw, data):
    byte = 0
    if En:
      byte = byte | 1 << self.pin['En']
    if Rs:
      byte = byte | 1 << self.pin['Rs']
    if Rw:
      byte = byte | 1 << self.pin['Rw']
    if self.backlight:
      byte = byte | 1 << self.pin['Backlight']
    if data & 0x01 :
      byte = byte | 1 << self.pin['D4']
    if data & 0x02 :
      byte = byte | 1 << self.pin['D5']
    if data & 0x04 :
      byte = byte | 1 << self.pin['D6']
    if data & 0x08 :
      byte = byte | 1 << self.pin['D7']
    self.lcd_device.write(byte)

  #  clocks  EN  to  latch  command
  def  lcd_strobe(self):
    self.lcd_device.write(self.lcd_device.read()  |  1 << self.pin['En'] )
    self.lcd_device.write(self.lcd_device.read()  &  (0xFF - (1<< self.pin['En'])) )

  #  write  a  command  to  lcd
  def  lcd_write(self,  cmd):
    self.low_level_write(En=False, Rs=False, Rw=False, data=(cmd>>4))
    self.lcd_strobe()
    self.low_level_write(En=False, Rs=False, Rw=False, data=(cmd&0x0F))
    self.lcd_strobe()
    self.low_level_write(En=False, Rs=False, Rw=False, data=0)

  #  write  a  character  to  lcd  (or  character  rom)
  def  lcd_write_char(self,  charvalue):
    self.low_level_write(En=False, Rs=True, Rw=False, data=(charvalue>>4))
    self.lcd_strobe()
    self.low_level_write(En=False, Rs=True, Rw=False, data=(charvalue&0x0F))
    self.lcd_strobe()
    self.low_level_write(En=False, Rs=False, Rw=False, data=0)

  #  put  char  function
  def  lcd_putc(self,  char):
    self.lcd_write_char(ord(char))

  #  put  string  function
  def  lcd_puts(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_putc(char)

  #  clear  lcd  and  set  to  home
  def  lcd_clear(self):
    self.lcd_write(0x1)
    self.lcd_write(0x2)

  #  add  custom  characters  (0  -  7)
  def  lcd_load_custon_chars(self,  fontdata):
    self.lcd_device.bus.write(0x40);
    for  char  in  fontdata:
      for  line  in  char:
        self.lcd_write_char(line)

if __name__ == '__main__':
  # define bus address, port, and pins
  display = lcd(0x27,1, Rs=0, Rw=1, En=2, Backlight=3, D4=4, D5=5, D6=6, D7=7)
  display.lcd_clear()
  # line 1 and line 2
  display.lcd_puts("I2C LCD on R-Pi",1)
  display.lcd_puts("       by gnawux",2)