LcdDisplay.HD44780.MCP23017 (lcd_display v0.2.0) View Source

Knows how to commuticate with HD44780 type display through the 16-bit I/O expander MCP23017. You can turn on/off the backlight and change the LED color by switching on/off red, green and blue.

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.MCP23017.start(config)

# Run a command and the display state will be updated.
{:ok, display} = LcdDisplay.HD44780.MCP23017.execute(display, {:print, "Hello world"})

# Turn on/off `:red`, `:green` and `:blue` to change the backlight color.
{:ok, display} = LcdDisplay.HD44780.MCP23017.execute(display, {:red, false})

# Pick a random backlight color.
{:ok, display} = LcdDisplay.HD44780.MCP23017.execute(display, :random_color)

Pin assignment

This module assumes the following pin assignment:

GPIOA

MCP23017	HD44780
GPA0	-
GPA1	-
GPA2	-
GPA3	-
GPA4	-
GPA5	-
GPA6	LED RED
GPA7	LED GREEN

GPIOB

MCP23017	HD44780
GPB0	LED BLUE
GPB1	DB7 (Data Bus 7)
GPB2	DB6 (Data Bus 6)
GPB3	DB5 (Data Bus 5)
GPB4	DB4 (Data Bus 4)
GPB5	E (Enable)
GPB6	-
GPB7	RS (Register Select)

Link to this section Summary

Types

config()

The configuration options.

display_driver()

rgb_key()

Functions

execute(display, command)

Executes the specified command and returns a new display state.

set_random_color(display)

start(config)

Initializes the LCD driver and returns the initial display state.

Link to this section Types

config()

Specs

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

The configuration options.

display_driver()

Specs

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

rgb_key()

Specs

rgb_key() :: :red | :green | :blue

Link to this section Functions

execute(display, command)

Executes the specified command and returns a new display state.

set_random_color(display)

Specs

set_random_color(display_driver()) :: display_driver()

start(config)

Specs

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

Initializes the LCD driver and returns the initial display state.