import i2c_lib
from time import sleep

# LCD Address
ADDRESS = 0x3e

# 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_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)

   # 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))

# put string function
   def lcd_display_string(self, string, line, offset):
       if line == 1:
           #0x80 | 0x00 = 0x80
           #self.lcd_write(0x80 + offset)
           self.lcd_write((LCD_SETDDRAMADDR | 0x00) + offset)
       if line == 2:
           #0x80 | 0x40 = 0xC0
           #self.lcd_write(0xC0 + offset)
           self.lcd_write((LCD_SETDDRAMADDR | 0x40) + offset)
       if line == 3:
           #0x80 | 0x14 = 0x94
           #self.lcd_write(0x94 + offset)
           self.lcd_write((LCD_SETDDRAMADDR | 0x14) + offset)
       if line == 4:
           #0x80 | 0x54 = D4
           #self.lcd_write(0xD4 + offset)
           self.lcd_write((LCD_SETDDRAMADDR | 0x54) + offset)

       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)