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from smbus import SMBus
from time import sleep
ALIGN_FUNC = {
'left': 'ljust',
'right': 'rjust',
'center': 'center'}
CLEAR_DISPLAY = 0x01
ENABLE_BIT = 0b00000100
LINES = {
1: 0x80,
2: 0xC0,
3: 0x94,
4: 0xD4}
LCD_BACKLIGHT = 0x08
LCD_NOBACKLIGHT = 0x00
class LCD(object):
def __init__(self, address=0x27, bus=1, width=20, rows=4, backlight=True):
self.address = address
self.bus = SMBus(bus)
self.delay = 0.0005
self.rows = rows
self.width = width
self.backlight_status = backlight
self.write(0x33)
self.write(0x32)
self.write(0x06)
self.write(0x0C)
self.write(0x28)
self.write(CLEAR_DISPLAY)
sleep(self.delay)
def _write_byte(self, byte):
self.bus.write_byte(self.address, byte)
self.bus.write_byte(self.address, (byte | ENABLE_BIT))
sleep(self.delay)
self.bus.write_byte(self.address,(byte & ~ENABLE_BIT))
sleep(self.delay)
def write(self, byte, mode=0):
backlight_mode = LCD_BACKLIGHT if self.backlight_status else LCD_NOBACKLIGHT
self._write_byte(mode | (byte & 0xF0) | backlight_mode)
self._write_byte(mode | ((byte << 4) & 0xF0) | backlight_mode)
def text(self, text, line, align='left'):
self.write(LINES.get(line, LINES[1]))
text, other_lines = self.get_text_line(text)
text = getattr(text, ALIGN_FUNC.get(align, 'ljust'))(self.width)
for char in text:
self.write(ord(char), mode=1)
if other_lines and line <= self.rows - 1:
self.text(other_lines, line + 1, align=align)
def backlight(self, turn_on=True):
self.backlight_status = turn_on
self.write(0)
def get_text_line(self, text):
line_break = self.width
if len(text) > self.width:
line_break = text[:self.width + 1].rfind(' ')
if line_break < 0:
line_break = self.width
return text[:line_break], text[line_break:].strip()
def clear(self):
self.write(CLEAR_DISPLAY)
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