Epad

epad is a virtual controller design to work together with Linux User input devices.

This project was based on two other similar projects:

• https://github.com/jehervy/node-virtual-gamepads
• https://github.com/sbidolach/mobile-gamepad

Both projects implement the same approach that epad does. But instead of nodejs, epad uses Elixir and Phoenix Framework.

retropie

The main use case is to be able to run epad as virtual controller to play video game emulation using retropie.

Installing and configuring epad on retropie

To install epad in retropie, there are basic Linux commands:

• First we need to install Erlang on raspberrypi (retropie):

sudo apt-get update
sudo apt-get install libssl-dev
sudo apt-get install ncurses-dev
curl -o otp_src_23.0.tar.gz http://www.erlang.org/download/otp_src_23.0.tar.gz
tar -xzvf otp_src_23.0.tar.gz
cd otp_src_23.0/
./configure
make
sudo make install
cd ..
rm otp_src_23.0.tar.gz
sudo rm -R otp_src_23.0/

• The second step is to download the epad release for raspberrypie4:

curl -Lo /tmp/epad-0.0.1-raspberrypi4.tar.gz https://github.com/joaohf/epad/releases/download/0.0.1/epad-0.0.1-raspberrypi4.tar.gz
sudo mkdir /opt/epad
sudo tar zxf /opt/epad-0.0.1-raspberrypi4.tar.gz -C /opt/epad

• After that, copy the epad config for retropie:

sudo cp /opt/epad/priv/retropie/MobileGamePad.cfg /opt/retropie/configs/all/retroarch-joypads/

• Install the systemd service file and run epad using systemd

sudo cp /opt/epad/priv/systemd/epad.service /etc/systemd/system
sudo systemctl daemon-reload
sudo systemctl enable epad.service
sudo systemctl start epad.service

• Get your phone and access http://retropie-IP:4000. You should be able to select the controller and interact with the retropie user interface.

Debugging uinput events

• Installing input-utils tool

sudo apt-get install input-utils

• Dump out all the input devices

sudo lsinput

• Display events

sudo input-events [number]

Development

This project follows the standard mix commands. The attention point is when testing and creating releases. If you are targeting a specific platform (like raspberrypi4) then make sure you source and configure your toolchain before calling mix release.

To release and cross compile:

mix phx.digest
MIX_PROD=prod mix release

To start your local development environment:

• Install dependencies with mix deps.get
• Install Node.js dependencies with npm install inside the assets directory
• Start Phoenix endpoint with iex -S mix phx.server

TODO

• Finish keyboard and touchpad implementations
• Add metrics layer
• Phoenix Framework cleanup

Contributing

Feel free to submit any PR. I will be happy to review and accept.

License

MIT

Parts of javascript frontend files and priv/retropi/MobileGamePad.cfg has borrowed from mobile-gamepad.