Class: Denko::Display::HD44780

Inherits:
Object
  • Object
show all
Includes:
Behaviors::MultiPin
Defined in:
lib/denko/display/hd44780.rb

Constant Summary collapse

LCD_CLEARDISPLAY =

Commands

0x01
LCD_RETURNHOME = 
0x02
LCD_ENTRYMODESET = 
0x04
LCD_DISPLAYCONTROL = 
0x08
LCD_CURSORSHIFT = 
0x10
LCD_FUNCTIONSET = 
0x20
LCD_SETCGRAMADDR = 
0x40
LCD_SETDDRAMADDR = 
0x80
LCD_ENTRYRIGHT =

Flags for display entry mode

0x00
LCD_ENTRYLEFT = 
0x02
LCD_ENTRYSHIFTINCREMENT = 
0x01
LCD_ENTRYSHIFTDECREMENT = 
0x00
LCD_DISPLAYON =

Flags for display on/off control

0x04
LCD_DISPLAYOFF = 
0x00
LCD_CURSORON = 
0x02
LCD_CURSOROFF = 
0x00
LCD_BLINKON = 
0x01
LCD_BLINKOFF = 
0x00
LCD_DISPLAYMOVE =

Flags for display/cursor shift

0x08
LCD_CURSORMOVE = 
0x00
LCD_MOVERIGHT = 
0x04
LCD_MOVELEFT = 
0x00
LCD_8BITMODE =

Flags for function set

0x10
LCD_4BITMODE = 
0x00
LCD_2LINE = 
0x08
LCD_1LINE = 
0x00
LCD_5x10DOTS = 
0x04
LCD_5x8DOTS = 
0x00
CONTROL_TOGGLES =

Create a #key_on and #key_off method for each feature in this hash, using the constant in the value to send a control signal.

Eg. #display_on and #display_off.

{
  display: LCD_DISPLAYON,
  cursor: LCD_CURSORON,
  blink: LCD_BLINKON,
}

Instance Attribute Summary

Attributes included from Behaviors::MultiPin

#pin, #pins, #proxies

Attributes included from Behaviors::Component

#board

Instance Method Summary collapse

Methods included from Behaviors::MultiPin

#before_initialize, #convert_pins, #proxy_pin, #proxy_states, #require_pin, #require_pins

Methods included from Behaviors::Component

#initialize, #micro_delay

Methods included from Behaviors::State

#initialize, #state

Instance Method Details

#after_initialize(options = {}) ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 65

def after_initialize(options={})
  super(options)
  
  # Default to 16x2 display if no options given.
  @columns = options[:columns] || 16
  @rows    = options[:rows]    || 2
  
  # Create a fuction set byte to set up the LCD. These defaults equal 0x00.
  @function = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS

  # Set 8-bit mode in the mask if d0-d3 are present.
  if (d0 && d1 && d2 && d3)
    @bits          = 8
    @function |= LCD_8BITMODE
  else
    @bits = 4
  end

  # Set 2 line (row) mode if needed.
  @function |= LCD_2LINE if (@rows > 1)

  # Some 1 line displays can use a 5x10 font.
  @function |= LCD_5x10DOTS if options[:tall_font] && (@rows == 1)
  
  # Offset memory address when moving cursor.
  # Row 2 always starts at memory address 0x40.
  # For 4 line LCDs:
  #   Row 3 is immediately after row 1, +16 or 20 bytes, depending on columns.
  #   Row 4 is immediately after row 2, +16 or 20 bytes, depending on columns.
  @row_offsets = [0x00, 0x40, 0x00+@columns, 0x40+@columns]
  
  # Wait 50ms for power to be > 2.7V, then pull everything low.
  micro_delay(50000)
  enable.low; rs.low; rw.low if rw

  # Start in 4-bit mode.
  if @bits == 4
    # Keep setting 8-bit mode until ready.
    command(0x03); micro_delay(4500)
    command(0x03); micro_delay(4500)
    command(0x03); micro_delay(150)
    
    # Set 4-bit mode.
    command(0x02)
    
  # Or start in 8 bit mode.
  else
    command(LCD_FUNCTIONSET | @function)
    micro_delay(4500)
    command(LCD_FUNCTIONSET | @function)
    micro_delay(150)
    command(LCD_FUNCTIONSET | @function)
  end
  
  # Set functions (lines, font size, etc.).
  command(LCD_FUNCTIONSET | @function)

  # Start with cursor off and no cursor blink.
  @control = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF
  display_on
  clear
  
  # Set entry mode defaults.
  @mode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT
  command(LCD_ENTRYMODESET | @mode)
  
  # Need this small delay to avoid garbage data on startup.
  sleep 0.05
end

#autoscroll_off ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 199

def autoscroll_off
  @mode &= ~LCD_ENTRYSHIFTINCREMENT;
  command(LCD_ENTRYMODESET | @mode);
end

#autoscroll_on ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 194

def autoscroll_on
  @mode |= LCD_ENTRYSHIFTINCREMENT;
  command(LCD_ENTRYMODESET | @mode);
end

#clear ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 135

def clear
  command(LCD_CLEARDISPLAY)
  micro_delay(2000)
end

#command(byte) ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 211

def command(byte)
  send(byte, board.low)
end

#create_char(location, bitmap) ⇒ Object

Define custom characters as bitmaps.



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# File 'lib/denko/display/hd44780.rb', line 205

def create_char(location, bitmap)
  location &= 0x7
  command(LCD_SETCGRAMADDR | (location << 3))
  bitmap.each { |byte| write byte }
end

#home ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 140

def home
  command(LCD_RETURNHOME)
  micro_delay(2000)
end

#initialize_pins(options = {}) ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 49

def initialize_pins(options={})
  # All the required pins.
  [:rs, :enable, :d4, :d5, :d6, :d7].each do |symbol|
    proxy_pin(symbol, DigitalIO::Output)
  end
  
  # If any of d0-d3 was given, make them all non-optional.
  lower_bits_optional = (self.pins.keys & [:d0, :d1, :d2, :d3]).empty?
  [:d0, :d1, :d2, :d3].each do |symbol|
    proxy_pin(symbol, DigitalIO::Output, optional: lower_bits_optional)
  end
  
  # RW pin is mostly hard-wired to ground, but can given.
  proxy_pin(:rw, DigitalIO::Output, optional: true)
end

#left_to_right ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 176

def left_to_right
  @mode |= LCD_ENTRYLEFT
  command(LCD_ENTRYMODESET | @mode)
end

#print(text) ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 152

def print(text)
  text.each_byte { |b| write b }
end

#pulse_enable ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 256

def pulse_enable
  enable.low
  micro_delay 1
  enable.high
  micro_delay 1
  enable.low
  micro_delay 100
end

#right_to_left ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 181

def right_to_left
  @mode &= ~LCD_ENTRYLEFT
  command(LCD_ENTRYMODESET | @mode)
end

#scroll_left ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 186

def scroll_left
  command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT)
end

#scroll_right ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 190

def scroll_right
  command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT)
end

#send(byte, rs_level) ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 219

def send(byte, rs_level)
  # RS pin goes low to send commands, high to send data.
  rs.write(rs_level) unless rs.state == rs_level
  rw.low if rw
  
  # Get the byte as a string of 0s and 1s, LSBFIRST.
  bits_from_byte = byte.to_s(2).rjust(8, "0").reverse
  
  # Write bits depending on connection.
  @bits == 8 ? write8(bits_from_byte) : write4(bits_from_byte)
end

#set_cursor(col, row) ⇒ Object Also known as: move_to 



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# File 'lib/denko/display/hd44780.rb', line 145

def set_cursor(col, row)
  # Limit to the highest row, 0 indexed.
  row = (@rows - 1) if row > (@rows - 1)
  command(LCD_SETDDRAMADDR | (col + @row_offsets[row]))
end

#write(byte) ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 215

def write(byte)
  send(byte, board.high)
end

#write4(bits) ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 231

def write4(bits)
  d4.write bits[4].to_i
  d5.write bits[5].to_i
  d6.write bits[6].to_i
  d7.write bits[7].to_i
  pulse_enable
  d4.write bits[0].to_i
  d5.write bits[1].to_i
  d6.write bits[2].to_i
  d7.write bits[3].to_i
  pulse_enable
end

#write8(bits) ⇒ Object 



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# File 'lib/denko/display/hd44780.rb', line 244

def write8(bits)
  d0.write bits[0].to_i
  d1.write bits[1].to_i
  d2.write bits[2].to_i
  d3.write bits[3].to_i
  d4.write bits[4].to_i
  d5.write bits[5].to_i
  d6.write bits[6].to_i
  d7.write bits[7].to_i
  pulse_enable
end