# i2c bus (0 -- original Pi, 1 -- Rev 2 Pi) I2CBUS = 0
# LCD Address ADDRESS = 0x3f
import smbus from time import sleep
class i2c_device: def __init__(self, addr, port=I2CBUS): self.addr = addr self.bus = smbus.SMBus(port)
# Write a single command def write_cmd(self, cmd): self.bus.write_byte(self.addr, cmd) sleep(0.0001)
# Write a command and argument def write_cmd_arg(self, cmd, data): self.bus.write_byte_data(self.addr, cmd, data) sleep(0.0001)
# Write a block of data def write_block_data(self, cmd, data): self.bus.write_block_data(self.addr, cmd, data) sleep(0.0001)
# Read a single byte def read(self): return self.bus.read_byte(self.addr)
# Read def read_data(self, cmd): return self.bus.read_byte_data(self.addr, cmd)
# Read a block of data def read_block_data(self, cmd): return self.bus.read_block_data(self.addr, cmd)
# 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 lcd: #initializes objects and lcd def __init__(self): self.lcd_device = i2c_device(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) sleep(0.2)
# clocks EN to latch command def lcd_strobe(self, data): self.lcd_device.write_cmd(data | En | LCD_BACKLIGHT) sleep(.0005) self.lcd_device.write_cmd(((data & ~En) | LCD_BACKLIGHT)) sleep(.0001)
def lcd_write_four_bits(self, data): self.lcd_device.write_cmd(data | LCD_BACKLIGHT) self.lcd_strobe(data)
# write a command to lcd def lcd_write(self, cmd, mode=0): self.lcd_write_four_bits(mode | (cmd & 0xF0)) self.lcd_write_four_bits(mode | ((cmd << 4) & 0xF0))
# write a character to lcd (or character rom) 0x09: backlight | RS=DR< # works! def lcd_write_char(self, charvalue, mode=1): self.lcd_write_four_bits(mode | (charvalue & 0xF0)) self.lcd_write_four_bits(mode | ((charvalue << 4) & 0xF0)) # put string function with optional char positioning def lcd_display_string(self, string, line=1, pos=0): 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)
# clear lcd and set to home def lcd_clear(self): self.lcd_write(LCD_CLEARDISPLAY) self.lcd_write(LCD_RETURNHOME)
# define backlight on/off (lcd.backlight(1); off= lcd.backlight(0) def backlight(self, state): # for 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)
# add custom characters (0 - 7) def lcd_load_custom_chars(self, fontdata): self.lcd_write(0x40); for char in fontdata: for line in char: self.lcd_write_char(line) |
