Scenic driver for fbcon?

jimsynz

Ash Core Team

Hi folks.

I’ve spent more than a few evenings fiddling around to get a custom system built that enables the st7789v display via the Linux fbtft driver as the console and the “hifiberry” DAC on the pirate audio board that I’m using.

Here’s a photo because it’s awesome:

The next step of the project is to start working on a Scenic based UI for the device. I’ve just tried throwing scenic_driver_nerves_rpi at it to see what happens, and while it seems to load and start correctly nothing is displayed on the console.

Currently installed is scenic 0.10.5 and scenic_driver_nerves_rpi 0.10.1.

The configuration is:

config :podbox, :viewport, %{
  name: :main_viewport,
  size: {240, 240},
  default_scene: Podbox.Scene.Main,
  drivers: [
    %{
      module: Scenic.Driver.Nerves.Rpi
    }
  ]
}

And the default scene is:

defmodule Podbox.Scenes.Main do
  use Scenic.Scene
  alias Scenic.Graph
  import Scenic.Primitives
  import Scenic.Components

  @graph Graph.build()
         |> text("Hello, World!", font_size: 22, translate: {20, 80})

  def init(_scene_args, _opts) do
    {:ok, %{graph: @graph}, push: @graph}
  end
end

Running Scenic.ViewPort.info(:main_viewport) returns:

{:ok,
 %Scenic.ViewPort.Status{
   drivers: %{
     #PID<0.2941.0> => %Scenic.ViewPort.Driver.Info{
       module: Scenic.Driver.Nerves.Rpi,
       type: "Static Monitor",
       id: nil,
       width: 1996092956,
       height: 1993753600,
       pid: #PID<0.2941.0>,
       private: nil
     }
   },
   root_config: {Podbox.Scene.Main, nil},
   root_graph: {:graph, Podbox.Scene.Main, nil},
   root_scene_pid: Podbox.Scene.Main,
   size: {240, 240},
   styles: %{},
   transforms: %{}
 }}

Does anyone have any idea what might be going wrong?

8 comments

/nerves /scenic

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2024-05-06 11:07:10 UTC

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jimsynz

Ash Core Team

I upgraded scenic to 0.11 and switched to scenic_driver_local. No luck so far.

Post #1

fmn

IT IS! thanks for sharing!

Post #2

jimsynz

Ash Core Team

Well I haven’t solved my scenic issue, but I wanted to share a photo of it in it’s case that I designed. so much fun in such a small package!

Post #3

al2o3cr

These seem extremely suspicious - do you get the same results every reboot?

The values don’t look endian-swapped (there’s too many 1s scattered around) but maybe they’re just random noise.

Post #4

jimsynz

Ash Core Team

Okay, so I’ve made some progress using Scenic 0.11.2.

The viewport is configured like this:

config :podbox, :viewport,
  name: :main_viewport,
  size: {240, 240},
  default_scene: Podbox.Scene.Main,
  drivers: [
    [
      module: Scenic.Driver.Local,
      name: :local,
      window: [resizeable: false, title: "Podbox"]
    ]
  ]

Manually starting Scenic shows the following in the console:

iex(1)> viewport = Application.get_env(:podbox, :viewport)
[
  name: :main_viewport,
  size: {240, 240},
  default_scene: Podbox.Scene.Main,
  drivers: [
    [
      module: Scenic.Driver.Local,
      name: :local,
      window: [resizeable: false, title: "Podbox"]
    ]
  ]
]
iex(2)> {:ok, pid} = Scenic.start_link([viewport])
{:ok, #PID<0.3204.0>}
scenic_driver_local error: "RPI driver error: Unable to query the default screen on HDMI"
scenic_driver_local puts: "Failed to initilize the device"
scenic_driver_local error: "RPI driver error: Unable to query the default screen on HDMI"
scenic_driver_local puts: "Failed to initilize the device"
scenic_driver_local error: "RPI driver error: Unable to query the default screen on HDMI"
scenic_driver_local puts: "Failed to initilize the device"
scenic_driver_local error: "RPI driver error: Unable to query the default screen on HDMI"
scenic_driver_local puts: "Failed to initilize the device"
scenic_driver_local error: "RPI driver error: Unable to query the default screen on HDMI"
scenic_driver_local puts: "Failed to initilize the device"
scenic_driver_local error: "RPI driver error: Unable to query the default screen on HDMI"
scenic_driver_local puts: "Failed to initilize the device"
scenic_driver_local error: "RPI driver error: Unable to query the default screen on HDMI"
scenic_driver_local puts: "Failed to initilize the device"
scenic_driver_local error: "RPI driver error: Unable to query the default screen on HDMI"
scenic_driver_local puts: "Failed to initilize the device"

Which totally makes sense, since I’m not using the default screen on HDMI. Any suggestions?

Post #5

03juan

The error comes from the default bcm.c driver.

If the display is available on /dev/dri/card0 then it looks like you can use the drm.c driver.

Have you tried manually setting a custom target?

export SCENIC_LOCAL_TARGET=drm
export SCENIC_LOCAL_GL=gles3

Post #6

jimsynz

Ash Core Team

Thanks for the update. Yeah, this is the direction I went down to finally get it working.

I wound up pulling scenic_driver_local from main and setting SCENIC_LOCAL_TARGET=cairo-fb. The only catch being that it expects to address the framebuffer on /dev/fb0 but my display is listed as /dev/fb1. In the mean time I have symlinked it, but I’ve also raised an issue asking for it to be made configurable. I think this means that this method will also work for any of the dozens of displays that are supported by fbtft without the need for custom scenic driver packages. Great news!