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lcdlib.py
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lcdlib.py
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#!/usr/bin/python
# -*- coding: utf-8 -*-
import smbus
from time import sleep
# I2C-Bus Port (raspberry default = 1)
I2C_PORT = 1
# 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
# 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
# control bits
LCD_EN = 0b00000100 # Enable bit
LCD_RS = 0b00000001 # Register select bit
class lcd:
# initializes objects and lcd
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~
def __init__(self, addr, rows=4, cols=16):
self.addr = addr # set device address
if rows <= 4: # set rows
self.rows = rows
else:
self.rows = 4
self.cols = cols # set columns
self.backlight_state = 'on' # state of backlight ('on', 'off')
self.display_state = 'on' # state of display ('on', 'off')
self.backlight_value = LCD_BACKLIGHT
self.cursor_state = 'hide' # state of cursor ('hide', 'on', 'blink')
self.row_state = 0 # actual cursor position
self.col_state = 0
self.bus = smbus.SMBus(I2C_PORT)
self.lcd_write_cmd(0x03)
self.lcd_write_cmd(0x03)
self.lcd_write_cmd(0x03)
self.lcd_write_cmd(0x02)
sleep(0.1)
self.lcd_write_cmd(LCD_FUNCTIONSET | LCD_2LINE | LCD_5x8DOTS | LCD_4BITMODE)
self.lcd_write_cmd(LCD_DISPLAYCONTROL | LCD_DISPLAYON)
self.lcd_write_cmd(LCD_CLEARDISPLAY)
self.lcd_write_cmd(LCD_ENTRYMODESET | LCD_ENTRYLEFT)
sleep(0.2)
# Low level functions
# ~~~~~~~~~~~~~~~~~~~
# Write a single i2c command (low level function)
def write_cmd(self, cmd):
self.bus.write_byte(self.addr, cmd | self.backlight_value)
sleep(0.0002)
# clocks EN to latch command (low level function)
def lcd_strobe(self, data):
self.write_cmd(data | LCD_EN)
sleep(.0005)
self.write_cmd(data & ~LCD_EN)
sleep(.0002)
# Write a nibble to the I2C bus (low level function)
def lcd_write_four_bits(self, data):
self.write_cmd(data)
self.lcd_strobe(data)
# write command to lcd (low level function)
def lcd_write_cmd(self, cmd):
self.lcd_write_four_bits((cmd & 0xF0))
self.lcd_write_four_bits(((cmd << 4) & 0xF0))
# write data to lcd (low level function)
def lcd_write_data(self, cmd):
self.lcd_write_four_bits(LCD_RS | (cmd & 0xF0))
self.lcd_write_four_bits(LCD_RS | ((cmd << 4) & 0xF0))
# LCD functions
# ~~~~~~~~~~~~~
# put string at cursor position
def write_string(self, string):
self.col_state = self.col_state + len(string)
for char in string:
self.lcd_write_data(ord(char))
# put string at position given by row and col
def display_string(self, string, row, col):
if row >= self.rows:
row = self.rows - 1
self.row_state = row
self.col_state = col + len(string)
row_offsets = [0x00, 0x40, self.cols, 0x40 + self.cols]
self.lcd_write_cmd(LCD_SETDDRAMADDR | (row_offsets[row] + col))
string = string.replace('ä', '\xE1').replace('Ä', '\xE1')
string = string.replace('ö', '\xEF').replace('Ö', '\xEF')
string = string.replace('ü', '\xF5').replace('Ü', '\xF5')
string = string.replace('ß', '\xE2')
for char in string:
self.lcd_write_data(ord(char))
# set cursor position
def set_cursor(self, row, col):
if row >= self.rows:
row = self.rows - 1
row_offsets = [0x00, 0x40, self.cols, 0x40 + self.cols]
self.row_state = row
self.col_state = col
self.lcd_write_cmd(LCD_SETDDRAMADDR | (col + row_offsets[row]))
# set cursor on
def cursor_on(self):
self.cursor_state = 'on'
self.lcd_write_cmd(LCD_DISPLAYCONTROL | LCD_DISPLAYON | LCD_CURSORON)
sleep(.05)
# set cursor blinking
def cursor_blink(self):
self.cursor_state = 'blink'
self.lcd_write_cmd(LCD_DISPLAYCONTROL | LCD_DISPLAYON | LCD_BLINKON)
sleep(.05)
# set cursor off
def cursor_off(self):
self.cursor_state = 'off'
self.lcd_write_cmd(LCD_DISPLAYCONTROL | LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF)
sleep(.05)
# set to home
def home(self):
self.row_state = 0
self.col_state = 0
self.lcd_write_cmd(LCD_RETURNHOME)
#sleep(1)
# clear lcd and set to home
def clear(self):
self.row_state = 0
self.col_state = 0
self.lcd_write_cmd(LCD_CLEARDISPLAY)
self.lcd_write_cmd(LCD_RETURNHOME)
#sleep(1)
# Move display left one position
def move_left(self):
self.col_state = self.col_state - 1
self.lcd_write_cmd(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT)
# Move display right one position
def move_right(self):
self.col_state = self.col_state + 1
self.lcd_write_cmd(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT)
# Switch display on
def display_on(self):
self.display_state = 'on'
self.lcd_write_cmd(LCD_DISPLAYCONTROL | LCD_DISPLAYON)
# Switch display off
def display_off(self):
self.display_state = 'off'
self.lcd_write_cmd(LCD_DISPLAYCONTROL | LCD_DISPLAYOFF)
# Switch backlight on
def backlight_on(self):
self.backlight_state = 'on'
self.backlight_value = LCD_BACKLIGHT
self.write_cmd(0)
# Switch backlight off
def backlight_off(self):
self.backlight_state = 'off'
self.backlight_value = LCD_NOBACKLIGHT
self.write_cmd(0)
# Fill one of the first 8 CGRAM locations with custom characters.
# The location parameter must be between 0 and 7 and pattern must
# provide an array of 8 bytes containing the pattern.
def create_char(self, location, pattern):
# only position 0..7 are allowed
location &= 0x7
self.lcd_write_cmd(LCD_SETCGRAMADDR | (location << 3))
for i in range(8):
self.lcd_write_data(pattern[i])
# Get backlight status
def get_backlight(self):
return self.backlight_state
# Get display status
def get_display(self):
return self.display_state
# Get cursor status
def get_cursor(self):
return self.cursor_state
# Get cursor row position
def get_row_pos(self):
return self.row_state
# Get cursor column position
def get_col_pos(self):
return self.col_state