#!/usr/bin/python

#
# based on code from lrvick and LiquidCrystal
# lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py
# LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp
#

from time import sleep


class Adafruit_CharLCD(object):

    # 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

    # 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

    def __init__(self, pin_rs=40, pin_e=38, pins_db=[31,33,35,37], GPIO=None):
        # Emulate the old behavior of using RPi.GPIO if we haven't been given
        # an explicit GPIO interface to use
        if not GPIO:
            import RPi.GPIO as GPIO
            GPIO.setwarnings(False)
        self.GPIO = GPIO
        self.pin_rs = pin_rs
        self.pin_e = pin_e
        self.pins_db = pins_db

        self.GPIO.setmode(GPIO.BOARD)
        self.GPIO.setup(self.pin_e, GPIO.OUT)
        self.GPIO.setup(self.pin_rs, GPIO.OUT)

        for pin in self.pins_db:
            self.GPIO.setup(pin, GPIO.OUT)

        self.write4bits(0x33)  # initialization
        self.write4bits(0x32)  # initialization
        self.write4bits(0x28)  # 2 line 5x7 matrix
        self.write4bits(0x0C)  # turn cursor off 0x0E to enable cursor
        self.write4bits(0x06)  # shift cursor right

        self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF

        self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS
        self.displayfunction |= self.LCD_2LINE

        # Initialize to default text direction (for romance languages)
        self.displaymode = self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)  # set the entry mode

        self.clear()

    def begin(self, cols, lines):
        if (lines > 1):
            self.numlines = lines
            self.displayfunction |= self.LCD_2LINE

    def home(self):
        self.write4bits(self.LCD_RETURNHOME)  # set cursor position to zero
        self.delayMicroseconds(3000)  # this command takes a long time!

    def clear(self):
        self.write4bits(self.LCD_CLEARDISPLAY)  # command to clear display
        self.delayMicroseconds(3000)  # 3000 microsecond sleep, clearing the display takes a long time

    def setCursor(self, col, row):
        self.row_offsets = [0x00, 0x40, 0x14, 0x54]
        if row > self.numlines:
            row = self.numlines - 1  # we count rows starting w/0
        self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))

    def noDisplay(self):
        """ Turn the display off (quickly) """
        self.displaycontrol &= ~self.LCD_DISPLAYON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def display(self):
        """ Turn the display on (quickly) """
        self.displaycontrol |= self.LCD_DISPLAYON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def noCursor(self):
        """ Turns the underline cursor off """
        self.displaycontrol &= ~self.LCD_CURSORON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def cursor(self):
        """ Turns the underline cursor on """
        self.displaycontrol |= self.LCD_CURSORON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def noBlink(self):
        """ Turn the blinking cursor off """
        self.displaycontrol &= ~self.LCD_BLINKON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def blink(self):
        """ Turn the blinking cursor on """
        self.displaycontrol |= self.LCD_BLINKON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def DisplayLeft(self):
        """ These commands scroll the display without changing the RAM """
        self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)

    def scrollDisplayRight(self):
        """ These commands scroll the display without changing the RAM """
        self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT)

    def leftToRight(self):
        """ This is for text that flows Left to Right """
        self.displaymode |= self.LCD_ENTRYLEFT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)

    def rightToLeft(self):
        """ This is for text that flows Right to Left """
        self.displaymode &= ~self.LCD_ENTRYLEFT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)

    def autoscroll(self):
        """ This will 'right justify' text from the cursor """
        self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)

    def noAutoscroll(self):
        """ This will 'left justify' text from the cursor """
        self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)

    def write4bits(self, bits, char_mode=False):
        """ Send command to LCD """
        self.delayMicroseconds(1000)  # 1000 microsecond sleep
        bits = bin(bits)[2:].zfill(8)
        self.GPIO.output(self.pin_rs, char_mode)
        for pin in self.pins_db:
            self.GPIO.output(pin, False)
        for i in range(4):
            if bits[i] == "1":
                self.GPIO.output(self.pins_db[::-1][i], True)
        self.pulseEnable()
        for pin in self.pins_db:
            self.GPIO.output(pin, False)
        for i in range(4, 8):
            if bits[i] == "1":
                self.GPIO.output(self.pins_db[::-1][i-4], True)
        self.pulseEnable()

    def delayMicroseconds(self, microseconds):
        seconds = microseconds / float(1000000)  # divide microseconds by 1 million for seconds
        sleep(seconds)

    def pulseEnable(self):
        self.GPIO.output(self.pin_e, False)
        self.delayMicroseconds(1)       # 1 microsecond pause - enable pulse must be > 450ns
        self.GPIO.output(self.pin_e, True)
        self.delayMicroseconds(1)       # 1 microsecond pause - enable pulse must be > 450ns
        self.GPIO.output(self.pin_e, False)
        self.delayMicroseconds(1)       # commands need > 37us to settle

    def message(self, text):
        """ Send string to LCD. Newline wraps to second line"""
        for char in text:
            if char == '\n':
                self.write4bits(0xC0)  # next line
            else:
                self.write4bits(ord(char), True)


if __name__ == '__main__':
    lcd = Adafruit_CharLCD()
    lcd.clear()
    lcd.message("  Adafruit 16x2\n  Standard LCD")
