off.py

#!/usr/bin/python3
#--------------------------------------
#    ___  ___  _ ____
#   / _ \/ _ \(_) __/__  __ __
#  / , _/ ___/ /\ \/ _ \/ // /
# /_/|_/_/  /_/___/ .__/\_, /
#                /_/   /___/
#
#  lcd_i2c.py
#  LCD test script using I2C backpack.
#  Supports 16x2 and 20x4 screens.
#
# Author : Matt Hawkins
# Date   : 20/09/2015
#
# http://www.raspberrypi-spy.co.uk/
#
# Copyright 2015 Matt Hawkins
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
#--------------------------------------
import smbus2
import time

I2C_ADDR  = 0x3F # I2C address
LCD_WIDTH = 16

LCD_CHR = 1
LCD_CMD = 0

LCD_LINE_1 = 0x80
LCD_LINE_2 = 0xC0
LCD_LINE_3 = 0x94
LCD_LINE_4 = 0xD4

# LCD_BACKLIGHT  = 0x08  # On
LCD_BACKLIGHT = 0x00  # Off

ENABLE = 0b00000100

E_PULSE = 0.0005
E_DELAY = 0.0005

#bus = smbus2.SMBus(0)  # Rev 1 Pi
bus = smbus2.SMBus(1) # Rev 2 Pi

def lcd_init():
  lcd_byte(0x33,LCD_CMD)
  lcd_byte(0x32,LCD_CMD)
  lcd_byte(0x06,LCD_CMD)
  lcd_byte(0x0C,LCD_CMD)
  lcd_byte(0x28,LCD_CMD)
  lcd_byte(0x01,LCD_CMD)
  time.sleep(E_DELAY)

def lcd_byte(bits, mode):

  bits_high = mode | (bits & 0xF0) | LCD_BACKLIGHT
  bits_low = mode | ((bits<<4) & 0xF0) | LCD_BACKLIGHT

  bus.write_byte(I2C_ADDR, bits_high)
  lcd_toggle_enable(bits_high)

  bus.write_byte(I2C_ADDR, bits_low)
  lcd_toggle_enable(bits_low)

def lcd_toggle_enable(bits):
  time.sleep(E_DELAY)
  bus.write_byte(I2C_ADDR, (bits | ENABLE))
  time.sleep(E_PULSE)
  bus.write_byte(I2C_ADDR,(bits & ~ENABLE))
  time.sleep(E_DELAY)

if __name__ == '__main__':

  try:
    lcd_init()
  except KeyboardInterrupt:
    pass
  finally:
    lcd_byte(0x01, LCD_CMD)