Scenic render and input driver for Waveshare display HAT for Raspberry PI

A library to provide a Scenic framework driver implementation for the display HAT for Raspberry PI from Waveshare. Inspired by Inky driver and Bonnet driver.

Currently supports:

• 128x128, 1.44inch LCD display HAT for Raspberry Pi
  • SKU: 13891
  • Part Number: 1.44inch LCD HAT
  • Brand: Waveshare

This driver only runs on RPi devices as far as we know as it is based on the scenic rpi driver generating a frame buffer we can use.

Installation

The package can be installed by adding scenic_driver_waveshare to your list of dependencies in mix.exs:

def deps do
  [
    {:scenic_driver_waveshare, "~> 0.8.2"}
  ]
end

Run mix deps.get to get the new dependency.

Usage

This library provides the Scenic.Driver.Nerves.Waveshare driver module.

An usage example is provided in alexiob/sample_scenic_driver_waveshare.

The driver configuration, to be placed in config/target.exs:

config :waveshare, :viewport, %{
  name: :main_viewport,
  default_scene: {Waveshare.Scene.Main, nil},
  # Match these to your display
  size: {128, 128},
  opts: [scale: 1.0],
  drivers: [
    %{
      module: Scenic.Driver.Nerves.Waveshare,
      opts: [
        # only :sku138191 at the moment
        device_sku: :sku138191,
        # :color18bit (default) | :color16bit | :color12bit
        color_depth: :color18bit,
        # :rgb | :bgr (default)
        color_order: :bgr,
        # :l2r_u2d | :l2r_d2u | :r2l_u2d | :r2l_d2u | :u2d_l2r | :u2d_r2l (default) | :d2u_l2r | :d2u_r2l
        scan_dir: :u2d_r2l,
        # :ppm | :rgb24 (default) | :rgb565 | :mono | :mono_column_scan
        capture_format: :rgb24,
        refresh_interval: 50,
        spi_speed_hz: 20_000_000,
        # remapping input keys
        input_mappings: %{
            button_3: "button_3_text"
        }
      ],
      name: :waveshare
    }
  ]
}

I strongly suggest to use the default values provided above.

For development on host, we recommend just using the glfw driver for Scenic.

The HAT inputs generate Scenic :key events:

def handle_input(
      {:key, {key, action, _something}} = event,
      _context,
      _state
    ) do

  Logger.debug(
    "handle_input: received event #{inspect(event)} state=#{inspect(state)}"
  )

  case {key, action} do
    {:joystick_1_up, :press} -> ...
    {:joystick_1_down, :press} -> ...
    {:joystick_1_right, :press} -> ...
    {:joystick_1_left, :press} -> ...
    {:joystick_1_button, :press} -> ...
    {:button_1, :press} -> ...
    {:button_2, :press} -> ...
    {:button_3, :press} -> ...
  end
end