Skip to content

Commit

Permalink
Clean up HD44780
Browse files Browse the repository at this point in the history
  • Loading branch information
@vickash
vickash committed Sep 23, 2024
1 parent 417847e commit 1c39370
Showing 1 changed file with 63 additions and 44 deletions.
107 changes: 63 additions & 44 deletions lib/denko/display/hd44780.rb
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,44 @@ class HD44780
LCD_5x10DOTS = 0x04
LCD_5x8DOTS = 0x00

def bits
@bits ||= 4
end

# Default to 16x2 display if columns and rows given.
def columns
@columns ||= params[:columns] || 16
end

def rows
@rows ||= params[:rows] || 2
end

# Fuction set byte to set up the LCD. These OR'ed defaults == 0x00.
def function
@function ||= LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS
end

# 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.
def row_offsets
@row_offsets ||= [0x00, 0x40, 0x00+columns, 0x40+columns]
end

# Start with cursor off and no cursor blink.
def control
@control ||= LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF
end

def entry_mode
@entry_mode ||= LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT
end

attr_writer :columns, :rows, :function, :bits, :row_offsets, :control, :entry_mode

def initialize_pins(options={})
# All the required pins.
[:rs, :enable, :d4, :d5, :d6, :d7].each do |symbol|
Expand All @@ -64,40 +102,24 @@ def initialize_pins(options={})
end

after_initialize do
# Default to 16x2 display if columns and rows given.
@columns = params[:columns] || 16
@rows = params[: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.
# Switch to 8-bit mode if d0-d3 are present.
if (d0 && d1 && d2 && d3)
@bits = 8
@function |= LCD_8BITMODE
else
@bits = 4
self.bits = 8
self.function |= LCD_8BITMODE
end

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

# Some 1 line displays can use a 5x10 font.
@function |= LCD_5x10DOTS if params[: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]
self.function |= LCD_5x10DOTS if params[:tall_font] && (rows == 1)

# 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
if bits == 4
# Keep setting 8-bit mode until ready.
command(0x03); micro_delay(4500)
command(0x03); micro_delay(4500)
Expand All @@ -108,24 +130,21 @@ def initialize_pins(options={})

# Or start in 8 bit mode.
else
command(LCD_FUNCTIONSET | @function)
command(LCD_FUNCTIONSET | function)
micro_delay(4500)
command(LCD_FUNCTIONSET | @function)
command(LCD_FUNCTIONSET | function)
micro_delay(150)
command(LCD_FUNCTIONSET | @function)
command(LCD_FUNCTIONSET | function)
end

# Set functions (lines, font size, etc.).
command(LCD_FUNCTIONSET | @function)
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)
# Write entry mode.
command(LCD_ENTRYMODESET | entry_mode)

# Need this small delay to avoid garbage data on startup.
sleep 0.05
Expand All @@ -143,8 +162,8 @@ def home

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]))
row = (rows - 1) if row > (rows - 1)
command(LCD_SETDDRAMADDR | (col + row_offsets[row]))
end
alias :move_to :set_cursor

Expand All @@ -165,21 +184,21 @@ def print(text)
}
CONTROL_TOGGLES.each_key do |key|
define_method (key.to_s << "_off").to_sym do
command LCD_DISPLAYCONTROL | (@control &= ~CONTROL_TOGGLES[key])
command LCD_DISPLAYCONTROL | (self.control &= ~CONTROL_TOGGLES[key])
end
define_method (key.to_s << "_on") do
command LCD_DISPLAYCONTROL | (@control |= CONTROL_TOGGLES[key])
command LCD_DISPLAYCONTROL | (self.control |= CONTROL_TOGGLES[key])
end
end

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

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

def scroll_left
Expand All @@ -191,13 +210,13 @@ def scroll_right
end

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

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

# Define custom characters as bitmaps.
Expand All @@ -224,7 +243,7 @@ def send(byte, rs_level)
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)
bits == 8 ? write8(bits_from_byte) : write4(bits_from_byte)
end

def write4(bits)
Expand Down

0 comments on commit 1c39370

Please sign in to comment.