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i2c_driver.py
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i2c_driver.py
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import smbus
import time
# LCD Address
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
class I2CDevice:
def __init__(self, addr, port=1):
self.addr = addr
self.bus = smbus.SMBus(port)
def write_cmd(self, cmd):
"""Write a single command"""
self.bus.write_byte(self.addr, cmd)
time.sleep(0.0001)
def write_cmd_arg(self, cmd, data):
self.bus.write_byte_data(self.addr, cmd, data)
time.sleep(0.0001)
def write_block_data(self, cmd, data):
"""Write a block of data"""
self.bus.write_block_data(self.addr, cmd, data)
time.sleep(0.0001)
def read(self):
"""Read a single byte"""
return self.bus.read_byte(self.addr)
def read_data(self, cmd):
return self.bus.read_byte_data(self.addr, cmd)
def read_block_data(self, cmd):
"""Read a block of data"""
return self.bus.read_block_data(self.addr, cmd)
class LCD:
def __init__(self):
"""Initializes objects and the LCD"""
self.lcd_device = I2CDevice(ADDRESS)
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)
time.sleep(0.2)
def lcd_strobe(self, data):
"""Clocks EN to latch command"""
self.lcd_device.write_cmd(data | En | LCD_BACKLIGHT)
time.sleep(.0005)
self.lcd_device.write_cmd(((data & ~En) | LCD_BACKLIGHT))
time.sleep(.0001)
def lcd_write_four_bits(self, data):
self.lcd_device.write_cmd(data | LCD_BACKLIGHT)
self.lcd_strobe(data)
def lcd_write(self, cmd, mode=0):
"""Write a command to lcd"""
self.lcd_write_four_bits(mode | (cmd & 0xF0))
self.lcd_write_four_bits(mode | ((cmd << 4) & 0xF0))
def lcd_write_char(self, charvalue, mode=1):
"""
Write a character to lcd (or character rom) 0x09: backlight
| RS=DR< works!
"""
self.lcd_write_four_bits(mode | (charvalue & 0xF0))
self.lcd_write_four_bits(mode | ((charvalue << 4) & 0xF0))
def lcd_display_string(self, string, line):
"""Put string function"""
if line == 1:
self.lcd_write(0x80)
if line == 2:
self.lcd_write(0xC0)
if line == 3:
self.lcd_write(0x94)
if line == 4:
self.lcd_write(0xD4)
for char in string:
self.lcd_write(ord(char), Rs)
def lcd_clear(self):
"""Clear lcd and set to home"""
self.lcd_write(LCD_CLEARDISPLAY)
self.lcd_write(LCD_RETURNHOME)
def backlight(self, state):
"""define backlight on/off (lcd.backlight(1); off= lcd.backlight(0)
state: 1=on, 0=off
"""
if state == 1:
self.lcd_device.write_cmd(LCD_BACKLIGHT)
elif state == 0:
self.lcd_device.write_cmd(LCD_NOBACKLIGHT)
def lcd_load_custom_chars(self, fontdata):
"""add custom characters (0 - 7)"""
self.lcd_write(0x40)
for char in fontdata:
for line in char:
self.lcd_write_char(line)
def lcd_display_string_pos(self, string, line, pos):
"""define precise positioning (addition from the forum)"""
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
self.lcd_write(0x80 + pos_new)
for char in string:
self.lcd_write(ord(char), Rs)