class I2C::Drivers::LCD::Display

Driver class for the 2004/1602 I2C LCD Display.

forked from https://github.com/nerab/i2c-ss1602

see github.com/andec/i2c Parts copied from github.com/paulbarber/raspi-gpio/blob/master/lcd_display.py

Constants

BIT_EN
BIT_RS
BIT_RW
COMMAND_CLEARDISPLAY

commands

COMMAND_CURSORSHIFT
COMMAND_DISPLAYCONTROL
COMMAND_ENTRYMODESET
COMMAND_FUNCTIONSET
COMMAND_RETURNHOME
COMMAND_SETCGRAMADDR
COMMAND_SETDDRAMADDR
FLAG_1LINE
FLAG_2LINE
FLAG_4BITMODE
FLAG_5x10DOTS
FLAG_5x8DOTS
FLAG_8BITMODE

flags for function set

FLAG_BACKLIGHT

flags for backlight control

FLAG_BLINKOFF
FLAG_BLINKON
FLAG_CURSORMOVE
FLAG_CURSOROFF
FLAG_CURSORON
FLAG_DISPLAYMOVE

flags for display/cursor shift

FLAG_DISPLAYOFF
FLAG_DISPLAYON

flags for display on/off control

FLAG_ENTRYLEFT
FLAG_ENTRYRIGHT

flags for display entry mode

FLAG_ENTRYSHIFTDECREMENT
FLAG_ENTRYSHIFTINCREMENT
FLAG_MOVELEFT
FLAG_MOVERIGHT
FLAG_NOBACKLIGHT
LCD_LINE_0

lcd ram address

LCD_LINE_1
LCD_LINE_2
LCD_LINE_3

Attributes

cols[R]
cursor[R]
device[R]
rows[R]

Public Class Methods

new(bus_or_bus_name, device_address, cols=20, rows=4, dotsize=8) click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 16
def initialize(bus_or_bus_name, device_address, cols=20, rows=4, dotsize=8)
  if bus_or_bus_name.respond_to?(:write)
    @device = BusDevice.new(bus_or_bus_name, device_address)
  else
    @device = BusDevice.new(I2C.create(bus_or_bus_name), device_address)
  end

  @cols = cols
  @rows = rows
  @dotsize = dotsize

  init_sequence

  @cursor = Cursor.new(self)
end

Public Instance Methods

backlight_off() click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 71
def backlight_off
  device.write(FLAG_NOBACKLIGHT)
end
backlight_on() click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 67
def backlight_on
  device.write(FLAG_BACKLIGHT)
end
clear() click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 32
def clear
  write(COMMAND_CLEARDISPLAY)
  write(COMMAND_RETURNHOME)
end
off() click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 63
def off
  write(COMMAND_DISPLAYCONTROL | FLAG_DISPLAYOFF)
end
on() click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 59
def on
  write(COMMAND_DISPLAYCONTROL | FLAG_DISPLAYON)
end
text(string, row, pad = false) click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 37
def text(string, row, pad = false)
  case row
  when 0
    write(LCD_LINE_0)
  when 1
    write(LCD_LINE_1)
  when 2
    write(LCD_LINE_2)
  when 3
    write(LCD_LINE_3)
  else
    raise "Only rows #{0..(@rows - 1)} are supported"
  end

  # Right-pad with spaces so that the line only shows string
  string = sprintf('%-1$*2$s', string, @cols) if pad

  string.each_char do |c|
    write(c.ord, BIT_RS)
  end
end
write(cmd, mode = 0) click to toggle source

Send a low-level command to the display

# File lib/i2c/drivers/lcd/display.rb, line 78
def write(cmd, mode = 0)
  write_four_bits(mode | (cmd & 0xF0))
  write_four_bits(mode | ((cmd << 4) & 0xF0))
end

Private Instance Methods

init_sequence() click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 161
def init_sequence
  write(0x03)
  write(0x03)
  write(0x03)
  write(0x02)

  write(COMMAND_FUNCTIONSET | FLAG_2LINE | FLAG_5x8DOTS | FLAG_4BITMODE)

  on
  clear
  write(COMMAND_ENTRYMODESET | FLAG_ENTRYLEFT)
  sleep(0.2)
end
strobe(data) click to toggle source

Clocks EN to latch command

# File lib/i2c/drivers/lcd/display.rb, line 178
def strobe(data)
  @device.write(data | BIT_EN | FLAG_BACKLIGHT)
  sleep(0.0005)
  @device.write(((data & ~BIT_EN) | FLAG_BACKLIGHT))
  sleep(0.001)
end
write_four_bits(data) click to toggle source
# File lib/i2c/drivers/lcd/display.rb, line 185
def write_four_bits(data)
  @device.write(data | FLAG_BACKLIGHT)
  strobe(data)
end