class I2C::Drivers::SS1602::Display

Driver class for the SainSmart 1602 I2C LCD Display.

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

Attributes

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

Public Class Methods

new(bus_or_bus_name, device_address) click to toggle source
# File lib/i2c/drivers/ss1602/display.rb, line 16
def initialize(bus_or_bus_name, device_address)
  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

  @rows = 2
  @cols = 16

  init_sequence

  @cursor = Cursor.new(self)
end

Public Instance Methods

clear() click to toggle source
# File lib/i2c/drivers/ss1602/display.rb, line 31
def clear
  write(COMMAND_CLEARDISPLAY)
  write(COMMAND_RETURNHOME)
end
off() click to toggle source
# File lib/i2c/drivers/ss1602/display.rb, line 58
def off
  write(COMMAND_DISPLAYCONTROL | FLAG_DISPLAYOFF)
end
on() click to toggle source
# File lib/i2c/drivers/ss1602/display.rb, line 54
def on
  write(COMMAND_DISPLAYCONTROL | FLAG_DISPLAYON)
end
text(string, row, pad = false) click to toggle source
# File lib/i2c/drivers/ss1602/display.rb, line 36
def text(string, row, pad = false)
  case row
  when 0
    write(0x80)
  when 1
    write(0xC0)
  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/ss1602/display.rb, line 65
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/ss1602/display.rb, line 142
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/ss1602/display.rb, line 159
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/ss1602/display.rb, line 166
def write_four_bits(data)
  @device.write(data | FLAG_BACKLIGHT)
  strobe(data)
end