LcdDisplay.HD44780.MCP23008 (lcd_display v0.3.0)

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Knows how to commuticate with HD44780 type display through the 8-bit I/O expander MCP23008. You can turn on/off the backlight.

Usage

iex(2)>  Circuits.I2C.detect_devices
Devices on I2C bus "i2c-1":
* 32  (0x20)

1 devices detected on 1 I2C buses
config = %{
  i2c_bus: "i2c-1",          # I2C bus name
  i2c_address: 0x20,         # 7-bit address
  rows: 2,                   # the number of display rows
  cols: 16,                  # the number of display columns
  font_size: "5x8"           # "5x10" or "5x8"
}

# Start the LCD driver and get the initial display state.
{:ok, display} = LcdDisplay.HD44780.MCP23008.start(config)

# Run a command and the display state will be updated.
{:ok, display} = LcdDisplay.HD44780.MCP23008.execute(display, {:print, "Hello world"})

Pin assignment

This module assumes the following pin assignment:

MCP23008HD44780
GP0-
GP1RS (Register Select)
GP2E (Enable)
GP3DB4 (Data Bus 4)
GP4DB5 (Data Bus 5)
GP5DB6 (Data Bus 6)
GP6DB7 (Data Bus 7)
GP7LED

Summary

Types

config()

The configuration options.

display_driver()

Functions

execute(display, command)

Executes the specified command and returns a new display state.

start(config)

Initializes the LCD driver and returns the initial display state.

Types

config()

@type config() :: %{
  optional(:rows) => String.t(),
  optional(:cols) => pos_integer(),
  optional(:font_size) => pos_integer()
}

The configuration options.

display_driver()

@type display_driver() :: LcdDisplay.HD44780.Driver.t()

Functions

execute(display, command)

Executes the specified command and returns a new display state.

start(config)

@spec start(config()) :: {:ok, display_driver()} | {:error, any()}

Initializes the LCD driver and returns the initial display state.