LcdDisplay.HD44780.Driver behaviour (lcd_display v0.3.0)

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Defines a behaviour required for an LCD driver.

Summary

Types

command()

Type that represents a supported display command. Some driver modules do not support the backlight LED commands.

config()
feature()

Type that represents an available display feature.

num_cols()
num_rows()
t()

Type that represents the display state.

Callbacks

execute(t, command)

Executes the specified command and returns a new display state.

start(config)

Initializes the LCD driver and returns the initial display state.

write_data(t, byte)

Sends a data byte to the display.

write_instruction(t, byte)

Sends an instruction byte to the display.

Functions

__using__(_)

Injects the common logic for an LCD driver. For display flags, please refer to HD44780 data sheet.

Types

command()

@type command() ::
  :clear
  | :home
  | {:print, String.t() | byte()}
  | {:set_cursor, integer(), integer()}
  | {:cursor, boolean()}
  | {:blink, boolean()}
  | {:display, boolean()}
  | {:autoscroll, boolean()}
  | {:text_direction, :right_to_left}
  | {:text_direction, :left_to_right}
  | {:scroll, integer()}
  | {:left, integer()}
  | {:right, integer()}
  | {:backlight, boolean()}
  | {:red, boolean()}
  | {:green, boolean()}
  | {:blue, boolean()}

Type that represents a supported display command. Some driver modules do not support the backlight LED commands.

Supported CommandDescription
:clearClear the display.
:homeMove the cursor home.
:printPrint a character or text at the current cursor.
:set_cursorSet the cursor position (row and column).
:cursorSwitch on/off the underline cursor.
:displaySwitch on/off the display without losing what is on it.
:blinkSwitch on/off the block cursor.
:autoscrollMake existing text shift when new text is printed.
:text_directionMake text flow left/right from the cursor.
:scrollScroll text left and right.
:leftMove the cursor left.
:rightMove the cursor right.
:backlightSwitch on/off the backlight.
:redSwitch on/off the red LED.
:greenSwitch on/off the green LED.
:blueSwitch on/off the blue LED.

config()

@type config() :: map()

feature()

@type feature() :: :entry_mode | :display_control

Type that represents an available display feature.

num_cols()

@type num_cols() :: 8..20

num_rows()

@type num_rows() :: 1..4

t()

@type t() :: %{
  :driver_module => atom(),
  :rows => num_rows(),
  :cols => num_cols(),
  :entry_mode => byte(),
  :display_control => byte(),
  :backlight => boolean(),
  required(atom()) => any()
}

Type that represents the display state.

Callbacks

execute(t, command)

@callback execute(t(), command()) :: {:ok, t()} | {:error, any()}

Executes the specified command and returns a new display state.

start(config)

@callback start(config()) :: {:ok, t()} | {:error, any()}

Initializes the LCD driver and returns the initial display state.

write_data(t, byte)

@callback write_data(t(), byte()) :: t()

Sends a data byte to the display.

write_instruction(t, byte)

@callback write_instruction(t(), byte()) :: t()

Sends an instruction byte to the display.

Functions

__using__(_)

(macro)

Injects the common logic for an LCD driver. For display flags, please refer to HD44780 data sheet.

Examples

use LcdDisplay.HD44780.Driver