backlight.py

#!/usr/bin/python
# -*- charset: utf-8 -*-
# This is a port of https://github.com/Seeed-Studio/Grove_LCD_RGB_Backlight
# (c) 2014 Helge Jung <helge.jung@youngage.eu>
# Released unter the LGPL, like the original.

from smbus import SMBus

class Backlight(object):
    REG_RED = 0x04 # pwm2
    REG_GREEN = 0x03 # pwm1
    REG_BLUE = 0x02 # pwm0

    REG_MODE1 = 0x00
    REG_MODE2 = 0x01
    REG_OUTPUT = 0x08

    def __init__(self, bus, address):
        if not isinstance(bus, SMBus):
            raise TypeError

        self.bus = bus
        self.address = int(address)

        # initialize
        self.set_register(self.REG_MODE1, 0)
        self.set_register(self.REG_MODE2, 0)

        # all LED control by PWM
        self.set_register(self.REG_OUTPUT, 0xAA)

    def set_register(self, addr, value):
        self.bus.write_byte_data(self.address, addr, value)

    def set_color(self, red, green, blue):
        r = int(red)
        g = int(green)
        b = int(blue)
        self.set_register(self.REG_RED, r)
        self.set_register(self.REG_GREEN, g)
        self.set_register(self.REG_BLUE, b)

if __name__ == '__main__':
    import time

    bus = SMBus(1)
    light = Backlight(bus, 0x62)

    light.set_color(255, 0, 0)
    time.sleep(1)
    light.set_color(0,255,0)
    time.sleep(1)
    light.set_color(0,0,255)
    time.sleep(1)
    light.set_color(255,0,255)
    time.sleep(1)
    light.set_color(255,255,255)
    time.sleep(1)
    light.set_color(0, 0, 128)