Is it possible to make a custom controller that'll be detected as a steam deck?

Community DIY Corner
1

Howdy guys!

I don’t know if it’s only me, but I find the current market for PC (steam) controllers is … depressing.
Since using my steam deck and changing the sticks to hall effect ones, I’m pretty sure that I’ve been spoiled. There’s literally nothing on the market that has all of the following:

  • hall-effect thumb stick
  • steam input native back paddles (no need for another program/app)
  • wireless (ideally bluetooth)

Hardware wise, those already exist. But there wasn’t the software (especially drivers) for such a controller. Until I realized that the steam deck is just the above, minus wireless but with 2 track pads!

If only I could make a controller that “tricks” steam thinking it being a steam deck (controller), I can make my perfect controller for PC!

Now here’s the question: is this spoofing even possible?

By probing lsusb on the steam deck, I can find 28de:1205 that says Valve Software Steam Controller - with the following interfaces:

  • HID (keyboard)
  • HID (mouse)
  • HID (unknown, shows bInterfaceProtocol=0)
  • bInterfaceClass=2 (Comminications), bInterfaceSubClass=2 (Abstract (Modem)), bInterfaceProtocol=1 (AT-commands (v.25ter))
  • bInterfaceClass=10 (CDC Data) (this should appear in /dev/serial/by-id)

Anyone has any idea what’s going on? That looks like a whole lot more than what the steam deck has (especially HID keyboard)

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Ok, looks like the serial number of 28de:1205 matches the “Steam Deck Controller ID” in “Settings → System”. (MEDA/MHDA + numbers)
So I guess this should be it …? Though that’s a bloody lot of interfaces to implement!

3

have you looked into “Steam Input” ? you can map basically any controller to any action using it when using steam

4

Basically, you want to use your Steamdeck as controller for your PC, right?

There exists the software VirtualHere which should make it possible
https://www.reddit.com/r/SteamDeck/comments/v22ddf/guide_how_to_use_your_deck_as_a_steam_input/

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5

The problem is, it looks like there aren’t any controllers with back paddles that can be used with steam input back paddles (I want that QoL). I haven’t tried yet (I can’t buy an elite2 just for testing), but that’s what my googke-fu said.

e.g. Elite2 back paddles are basically mapped to other buttons in the controller, so they show as a normal controller on steam input. Technically there’s a program that lets you remap it from your PC, but I’d like to avoid that. (again, QoL)

Not really, that’s too heavy for my liking. (Although That is interesting)
A controller that can accept the same inputs (to a certain degree) is what I want.

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Xbox elite controller and their clones have backpaddles and should be possible to get remapped

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7

A quick google search shows that they’re not really supported. Has this changed?
Tldr: older firmware works (to a certain degree), but the new production ones (since Jan 2023) might not be able to roll back.

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