Force feedback wheel support – status 3

As explained in status 1, GIMX has to convert the FFB report stream so that it can be transmitted to a wheel that cannot handle reports as fast as a G29 (my Momo racing wheel can handle one report each 8ms, and the G29 one report each 4ms). I wrote some code that handles this task the following way:

  1. on reception, decode the report according to the protocol specification (published by Logitech here), and only handle “download and play” and “stop” commands
  2. store the status of the effect into a slot (there are up to 4 effects), and push the effect id into a fifo
  3. if no write is pending:
    1. if multiple effects have to be stopped, build a report to stop them, and remove the effects from the fifo
    2. otherwise, get the next effect to update from the fifo (if any), and build a report
    3. finally, if a report has to be written, write it (this is non-blocking)
  4. when writing is complete (this is notified asynchronously), execute step 3

And that’s it, I made my Momo Racing wheel work with my PS4, including force-feedback!

My last task will be to make the code more generic so that other Logitech wheels can be used.

12 Replies to “Force feedback wheel support – status 3”

  1. can you make a video? wow
    i have a g27 and i’m crazy with no compatibility with ps4!
    any plan for sale this build or help some layman?

    1. My plan is to make it work for most of the Logitech wheels, including the G27.
      It requires to build a DIY USB adapter from cheap (less than 30$) hardware parts (no soldering required).
      You can learn how to make one on the wiki (linked in the menu of this blog).
      FFB support will be added in GIMX version 5.

  2. Wow, impresive what you’ve achieved.
    I’m looking forward to make my own adapter to use it with my Dirving Force GT, but I must learn to make the adapter firstly.

    Thank you for what you’re doing. Keep the hard work.

    1. Hi,
      1. I can’t buy a G920, so I either need more donations, or someone to buy it and to give me information about it.
      2. I’m working on making this possible. I’m planning this for GIMX 5.0.

        1. The Hori racing wheel has no force feedback.
          The whole point of getting a G920 is that it’s a Logitech wheel. The FFB protocol used by Logitech is known as they published it, and almost any Logitech wheel uses this protocol.

  3. Just wanted to say … what a great job!

    I’ve put the usb adapter together in less than a day and got my G27 emulated to G29.

    Currently playing Drive Club, and while I don’t have any big issues, the steering feels very very slightly less direct, so I get a lot of under-steering… perhaps is the game; will try with Project Cars in the next couple of days.

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