lcd_driver.py

import i2c_lib
from time import *

# LCD Address
ADDRESS = 0x3f

# 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

class lcd:
   #initializes objects and lcd
   def __init__(self):
      self.lcd_device = i2c_lib.i2c_device(ADDRESS)

      self.lcd_write0(0x03)
      self.lcd_write0(0x03)
      self.lcd_write0(0x03)
      self.lcd_write0(0x02)

      self.lcd_write0(LCD_FUNCTIONSET | LCD_2LINE | LCD_5x8DOTS | LCD_4BITMODE)
      self.lcd_write0(LCD_DISPLAYCONTROL | LCD_DISPLAYON)
      self.lcd_write0(LCD_CLEARDISPLAY)
      self.lcd_write0(LCD_ENTRYMODESET | LCD_ENTRYLEFT)
      sleep(0.2)

   # clocks EN to latch command
   def lcd_strobe0(self, data):
      self.lcd_device.write_cmd(data | En | LCD_NOBACKLIGHT)
      sleep(.0005)
      self.lcd_device.write_cmd(((data & ~En | LCD_NOBACKLIGHT)))
      sleep(.0001)

   def lcd_strobe1(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_bits0(self, data):
      self.lcd_device.write_cmd(data | LCD_NOBACKLIGHT)
      self.lcd_strobe0(data)

   def lcd_write_four_bits1(self, data):
      self.lcd_device.write_cmd(data | LCD_BACKLIGHT)
      self.lcd_strobe1(data)

   # write a command to lcd
   def lcd_write0(self, cmd, mode=0):
      self.lcd_write_four_bits0(mode | (cmd & 0xF0))
      self.lcd_write_four_bits0(mode | ((cmd << 4) & 0xF0))

   def lcd_write1(self, cmd, mode=0):
      self.lcd_write_four_bits1(mode | (cmd & 0xF0))
      self.lcd_write_four_bits1(mode | ((cmd << 4) & 0xF0))

   # put string function
   def lcd_display_string0(self, string, line):
      if line == 1:
         self.lcd_write0(0x80)
      if line == 2:
         self.lcd_write0(0xC0)
      if line == 3:
         self.lcd_write0(0x94)
      if line == 4:
         self.lcd_write0(0xD4)

      for char in string:
         self.lcd_write0(ord(char), Rs)

   def lcd_display_string1(self, string, line):
      if line == 1:
         self.lcd_write1(0x80)
      if line == 2:
         self.lcd_write1(0xC0)
      if line == 3:
         self.lcd_write1(0x94)
      if line == 4:
         self.lcd_write1(0xD4)

      for char in string:
         self.lcd_write1(ord(char), Rs)

   # clear lcd and set to home
   def lcd_clear0(self):
      self.lcd_write0(LCD_CLEARDISPLAY)
      self.lcd_write0(LCD_RETURNHOME)

   def lcd_clear1(self):
      self.lcd_write1(LCD_CLEARDISPLAY)
      self.lcd_write1(LCD_RETURNHOME)

   def lcd_write_char0(self, charvalue, mode=1):
      self.lcd_write_four_bits0(mode | (charvalue & 0xF0))
      self.lcd_write_four_bits0(mode | ((charvalue << 4) & 0xF0))

   def lcd_write_char1(self, charvalue, mode=1):
      self.lcd_write_four_bits1(mode | (charvalue & 0xF0))
      self.lcd_write_four_bits1(mode | ((charvalue << 4) & 0xF0))

   def lcd_load_custom_chars0(self, fontdata):
      self.lcd_write0(0x40);
      for char in fontdata:
         for line in char:
            self.lcd_write_char0(line)

   def lcd_load_custom_chars1(self, fontdata):
      self.lcd_write1(0x40);
      for char in fontdata:
         for line in char:
            self.lcd_write_char1(line)

   # define precise positioning (addition from the forum)
   def lcd_display_string_pos0(self, string, line, pos):
    if line == 1:
      pos_new = pos
    elif line == 2:
      pos_new = 0x40 + pos
    elif line == 3:
      pos_new = 0x14 + pos
    elif line == 4:
      pos_new = 0x54 + pos

    self.lcd_write0(0x80 + pos_new)

    for char in string:
      self.lcd_write0(ord(char), Rs)

   # define precise positioning (addition from the forum)
   def lcd_display_string_pos1(self, string, line, pos):
    if line == 1:
      pos_new = pos
    elif line == 2:
      pos_new = 0x40 + pos
    elif line == 3:
      pos_new = 0x14 + pos
    elif line == 4:
      pos_new = 0x54 + pos

    self.lcd_write1(0x80 + pos_new)

    for char in string:
      self.lcd_write1(ord(char), Rs)