# -*- coding: utf-8 -*-
"""
GPL-licensed code found on GitHub Gists, contained below with some slight
adjustments. Taken 2017-3-26.
https://gist.github.com/DenisFromHR/cc863375a6e19dce359d#file-rpi_i2c_driver-py
"""
"""
Compiled, mashed and generally mutilated 2014-2015 by Denis Pleic
Made available under GNU GENERAL PUBLIC LICENSE
# Modified Python I2C library for Raspberry Pi
# as found on http://www.recantha.co.uk/blog/?p=4849
# Joined existing 'i2c_lib.py' and 'lcddriver.py' into a single library
# added bits and pieces from various sources
# By DenisFromHR (Denis Pleic)
# 2015-02-10, ver 0.1
"""
import smbus
from time import *
# TODO: Organize these in some better way, maybe a dict or something?
# LCD Address
# Default to 0x27, for RPi3 I2C device
ADDRESS = 0x27
# 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
[docs]class i2c_device:
"""Class for communicating with I2C devices over SMBus.
Used to help the lcd class communicate with an I2C device via SMBus.
Args:
addr (hex str): Hex address of I2C device
port (int): port for SMBus
"""
def __init__(self, addr=ADDRESS, port=1):
self.addr = addr
self.bus = smbus.SMBus(port)
[docs] def write_cmd(self, cmd):
"""Write a single command.
Args:
cmd (hex str): Hex command.
"""
self.bus.write_byte(self.addr, cmd)
sleep(0.0001)
[docs]class lcd:
"""Class for interfacing with I2C LCD device."""
def __init__(self, addr=ADDRESS):
self.lcd_device = i2c_device(addr)
# TODO: Why write all of these? Assuming they're necessary to init.
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)
[docs] def lcd_strobe(self, data):
"""Clocks enable bit to latch command.
Args:
data: data to write
"""
self.lcd_device.write_cmd(data | En | LCD_BACKLIGHT)
sleep(.0005)
self.lcd_device.write_cmd(((data & ~En) | LCD_BACKLIGHT))
sleep(.0001)
[docs] def lcd_write_four_bits(self, data):
"""Write four bits of data to lcd device.
Args:
data: data to write
"""
self.lcd_device.write_cmd(data | LCD_BACKLIGHT)
self.lcd_strobe(data)
# write a command to lcd
[docs] def lcd_write(self, cmd, mode=0):
"""Write a command to lcd.
Args:
cmd (hex str): Hex command.
mode (int): Mode? Defaults to 0.
"""
self.lcd_write_four_bits(mode | (cmd & 0xF0))
self.lcd_write_four_bits(mode | ((cmd << 4) & 0xF0))
[docs] def lcd_write_char(self, charvalue, mode=1):
"""Writes char to lcd.
Notes from original:
"write a character to lcd (or character rom) 0x09:
backlight | RS=DR<"
Args:
charvalue (int): ordinal value of character to write.
mode (int): Mode? Defaults to 1.
"""
self.lcd_write_four_bits(mode | (charvalue & 0xF0))
self.lcd_write_four_bits(mode | ((charvalue << 4) & 0xF0))
# Couldn't we just do this?
# self.lcd_write(charvalue, mode=1)
[docs] def lcd_display_string(self, string, line):
"""Displays string on lcd screen.
Args:
string (str): String to be displayed.
line (int): Line for string to be displayed on. Must be 1-4.
"""
if line == 1:
self.lcd_write(0x80)
elif line == 2:
self.lcd_write(0xC0)
elif line == 3:
self.lcd_write(0x94)
elif line == 4:
self.lcd_write(0xD4)
else:
raise Exception("Line parameter must be 1, 2, 3, or 4.")
for char in string:
self.lcd_write(ord(char), Rs)
# Could we use lcd_write_char?
# self.lcd_write_char(char, Rs)
[docs] def lcd_clear(self):
"""Clear lcd and set to home."""
self.lcd_write(LCD_CLEARDISPLAY)
self.lcd_write(LCD_RETURNHOME)
[docs] def backlight_on(self, set_to_on):
"""Define backlight as on/off.
Args:
set_to_on (bool): True sets backlight on, False sets off.
"""
if set_to_on:
self.lcd_device.write_cmd(LCD_BACKLIGHT)
else:
self.lcd_device.write_cmd(LCD_NOBACKLIGHT)
[docs] def lcd_load_custom_chars(self, fontdata):
"""Load custom characters from font data.
Args:
fontdata (char[]): font data, max 7 characters.
"""
self.lcd_write(0x40)
for line in fontdata:
for char in line:
self.lcd_write_char(char)
[docs] def lcd_display_string_pos(self, string, line, pos):
"""Display string in precise position/offset.
Args:
string (str): String to be displayed.
line (int): Line for string to be displayed on. Must be 1-4.
pos (int): Offset for displaying string
"""
if line == 1:
pos_new = pos
elif line == 2:
pos_new = 0x40 + pos
elif line == 3:
pos_new = 0x14 + pos
elif line == 4:
pos_new = 0x54 + pos
else:
raise Exception("Line parameter must be 1, 2, 3, or 4.")
self.lcd_write(0x80 + pos_new)
for char in string:
self.lcd_write(ord(char), Rs)
# Could we use lcd_write_char?
# self.lcd_write_char(char, Rs)