#!/usr/bin/env python
#
# GrovePi Example for using the Grove - LCD RGB Backlight (http://www.seeedstudio.com/wiki/Grove_-_LCD_RGB_Backlight)
#
# The GrovePi connects the Raspberry Pi and Grove sensors.  You can learn more about GrovePi here:  http://www.dexterindustries.com/GrovePi
#
# Have a question about this example?  Ask on the forums here:  http://forum.dexterindustries.com/c/grovepi
#
# History
# ------------------------------------------------
# Author        Date                    Comments
#                                                       Initial Authoring
# Karan         7 Jan 16                Library updated to add a function to update the text without erasing the screen
# Released under the MIT license (http://choosealicense.com/licenses/mit/).
# For more information see https://github.com/DexterInd/GrovePi/blob/master/LICENSE

#
# NOTE:
#       Just supports setting the backlight colour, and
#       putting a single string of text onto the display
#       Doesn't support anything clever, cursors or anything

import time,sys

if sys.platform == 'uwp':
    import winrt_smbus as smbus
    bus = smbus.SMBus(1)
else:
    import smbus
    import RPi.GPIO as GPIO
    rev = GPIO.RPI_REVISION
    if rev == 2 or rev == 3:
        bus = smbus.SMBus(1)
    else:
        bus = smbus.SMBus(0)

# this device has two I2C addresses
DISPLAY_RGB_ADDR = 0x62
DISPLAY_TEXT_ADDR = 0x3e

# set backlight to (R,G,B) (values from 0..255 for each)
def setRGB(r,g,b):
    bus.write_byte_data(DISPLAY_RGB_ADDR,0,0)
    bus.write_byte_data(DISPLAY_RGB_ADDR,1,0)
    bus.write_byte_data(DISPLAY_RGB_ADDR,0x08,0xaa)
    bus.write_byte_data(DISPLAY_RGB_ADDR,4,r)
    bus.write_byte_data(DISPLAY_RGB_ADDR,3,g)
    bus.write_byte_data(DISPLAY_RGB_ADDR,2,b)

# send command to display (no need for external use)
def textCommand(cmd):
    bus.write_byte_data(DISPLAY_TEXT_ADDR,0x80,cmd)

# set display text \n for second line(or auto wrap)
def setText(text):
    textCommand(0x01) # clear display
    time.sleep(.05)
    textCommand(0x08 | 0x04) # display on, no cursor
    textCommand(0x28) # 2 lines
    time.sleep(.05)
    count = 0
    row = 0
    for c in text:
        if c == '\n' or count == 16:
            count = 0
            row += 1
            if row == 2:
                break
            textCommand(0xc0)
            if c == '\n':
                continue
        count += 1
        bus.write_byte_data(DISPLAY_TEXT_ADDR,0x40,ord(c))

#Update the display without erasing the display
def setText_norefresh(text):
    textCommand(0x02) # return home
    time.sleep(.05)
    textCommand(0x08 | 0x04) # display on, no cursor
    textCommand(0x28) # 2 lines
    time.sleep(.05)
    count = 0
    row = 0
    while len(text) < 32: #clears the rest of the screen
        text += ' '
    for c in text:
        if c == '\n' or count == 16:
            count = 0
            row += 1
            if row == 2:
                break
            textCommand(0xc0)
            if c == '\n':
                continue
        count += 1
        bus.write_byte_data(DISPLAY_TEXT_ADDR,0x40,ord(c))

# Create a custom character (from array of row patterns)
def create_char(location, pattern):
    """
    Writes a bit pattern to LCD CGRAM

    Arguments:
    location -- integer, one of 8 slots (0-7)
    pattern -- byte array containing the bit pattern, like as found at
               https://omerk.github.io/lcdchargen/
    """
    location &= 0x07 # Make sure location is 0-7
    textCommand(0x40 | (location << 3))
    bus.write_i2c_block_data(DISPLAY_TEXT_ADDR, 0x40, pattern)

# example code
if __name__=="__main__":
    setText("Hello world\nThis is an LCD test")
    setRGB(0,128,64)
    time.sleep(2)
    for c in range(0,255):
        setText_norefresh("Going to sleep in {}...".format(str(c)))
        setRGB(c,255-c,0)
        time.sleep(0.1)
    setRGB(0,255,0)
    setText("Bye bye, this should wrap onto next line")