Posts for 2024 July

Homeboard P0: Stonebaked Margherita Picture frame

Post by Nico Brailovsky @ 2024-07-18 | Permalink | Leave a comment

With my homeboard booting up, it's time to make it show something. Some day I'll build a net-boot capable system, but until then I'd like to have it do something, even if it's by installing a few services by hand.

OS

Starting with a base Raspbian Bookworm for Rpi Zero (32 bit), with no GUI:

Prepare Wayland

Raspbian Bookworm 32bit doesn't have support for Wayland out of the box. To enable:

dtoverlay=vc4-kms-v3d
gpu_mem=128

Screen rotation

Because of the way the flex cable is fed to the HDMI-to-eDP board, the screen may end up rotated 180 degrees. You may also want a portrait picture frame, instead of a landscape one. To rotate Wayland:

  1. Do kmsprint or kmsprint -m
  2. Look for the name of the screen, eg HDMI-A-1
  3. Look for the mode, eg 1920x1080@60.00
  4. Create this in ~/.config/wayfire.ini, replacing the values found above for your setup
[output:HDMI-A-1]
mode = 1920X1080@60.00
position = 0,0
transform = 90

No need to reboot Wayfire, it should pick up the changes and fix itself immediately. I think.

swayimg

With a GUI, it's time to show a picture. I hacked swayimg to load pictures from a local server, plus a few other useful features to make it more usable in a RpiW, like consuming less memory than default, and porting to 32 bits. To install dependencies:

sudo apt-get install libcurl git ninja-build meson
sudo apt-get install libcurl4-openssl-dev
sudo apt-get install libwayland-dev wayland-protocols
sudo apt-get install libjson-c-dev libxkbcommon-dev libfontconfig-dev libjpeg-dev

To build: [Yes, this is building swayimg in our target. This is horrible and will take a long time, so be prepared for a long coffee break. Some day I'll setup a crosscompiler].

git clone https://github.com/nicolasbrailo/swayimg.git
meson setup [build|--wipe build]
ninja -C build

To start:

Check that nothing crashes too much.

P0 picture frame

With everything "working", we can make Wayfire and swayimg a system service, so they'll start at boot:

Add this to /etc/systemd/system/wayfire.service (change the user name):

[Unit]
Description=wayfire
After=multi-user.target
[Service]
Environment=XDG_RUNTIME_DIR=/run/user/1000
ExecStart=wayfire
StandardOutput=inherit
StandardError=inherit
Restart=always
RestartSec=10s
User=batman
[Install]
WantedBy=multi-user.target

Also this to /etc/systemd/system/ambience.service (also change the user name. Or make a new user):

[Unit]
Description=ambience
After=multi-user.target
[Service]
Environment=XDG_RUNTIME_DIR=/run/user/1000 WAYLAND_DISPLAY="wayland-1" DISPLAY=""
ExecStart=/home/batman/swayimg/build/swayimg
StandardOutput=inherit
StandardError=inherit
Restart=always
RestartSec=3s
User=batman
[Install]
WantedBy=multi-user.target

Then:

sudo systemctl enable wayfire
sudo systemctl enable ambiene
sudo systemctl restart wayfire
sudo systemctl restart ambience

Next time you boot up, the Stonebaked Margherita P0 frame should behave like a picture frame.

Homeboard P0: Stonebaked Margherita

Post by Nico Brailovsky @ 2024-07-14 | Permalink | Leave a comment

Homeboard P0 has been built!!1

After figuring out how to run my own LCD panel, it was just a question of buying the right cables. I wanted to build a homeboard, and I thought I'd spend a ton of time writing cool software. Turns out 90% of the project is a game of "did I buy the right cable". Eventually I did end up with enough cables to build this monstrosity:

You are admiring a:

(Full list of materials further down, so you don't need to hunt all of these)

Here the glorious moment everything is connected together, and actually boots an OS:

Of course at this point I realized the weak point of my design is on the mechanical linkage between the different boards. To tame this quite literally unwieldy hodgepodge of cables, I ate a pizza:

Using the cardboard box of a pizza, some ducktape and a few M2 screws, I built a beautiful hack mount for all my boards, which let me move the assembly around for tests. This was enough for quick power checks, but pizza box cardboard isn't a very durable material. I upgraded to a full frame:

This is an Ikea picture frame, with an LCD screen tapped to the front and a hole in the back for the eDP connector. Everything mounted together:

And the glorious, glorious first boot of the Stonebaked Margherita Homeboard P0:

Of course at this stage the only thing the Houseboard P0 does is boot. An achievement, but not too useful. Next up, I'll make it do something. Possibly crash.

BoM

Optionals:

Useful references

Houseboard P0: HDMI to eDP

Post by Nico Brailovsky @ 2024-07-07 | Permalink | Leave a comment

Minor victory in my quest to build a houseboard based on a Linux-PoE-netboot-RaspberryPi-etc: I figured out how to run my own LCD panel.

The first step was verifying my panel worked. For this, I used a display port to eDP converter. Turns out eDP is basically DP, but over a ribbon cable. There are some cheap boards, for example, that do this - searching for "DP to eDP" or "display port to eDP" will yield a high number of vendors. The key part is matching the ribbon type of the panel you need to drive (30 or 40 pins).

Unfortunatelly, single-board-computers (like the RaspberryPi) don't have DP, despite DP being better than HDMI in every way. The cost of adding a DP connector seems to be high and mosty in licenses, not necessarily in components, so SBCs don't do it. This meant that getting my expensive GPU to use my cheap panel wasn't good for much beyond knowing the panel works.

Fortunatelly, I managed to find a board that liked my panel:

I got a "PCB-800807V6-1HDMI-EDP 30PIN LCD driver board", which comes at about £10 and supports multiple resolutions. This was a nice lucky find, and it unblocked the build of HouseboardP0, which I'll document in some other entry.

Make sure the meson step finds curl and libjpeg, otherwise it won't be a very useful LAN picture frame.