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+# Contributing
+
+## Overview This file contains general contributing information.
+
+This project is seeking for help from people who can contribute. If you have a
+wheel that's not on the list, but suspect it might fit into the driver, please
+feel free to open up an issue about it.
+
+Other documents available are linked here:
+
++ [FFBEEFFECTS](./FFBEFFECTS.md):
+  Force feedback effects example for T300RS and compatible wheels
+
++ [STRUCTURE](./STRUCTURE.md):
+  Structure of Thrustmaster device stack
+
++ [DRIVER.md](./DRIVER.md):
+  Info on installing Thrustmaster drivers under Wine
+
++ [TODO](./TODO.md):
+  TODO list for maintainers
+
+## How to capture what effects a game sends to the driver?
+
+Use ffbwrap from ffbtools:
+[github:berarma/ffbtools](https://github.com/berarma/ffbtools)
+
+The documentation gives good examples, but tl;dr; For steam, insert the following
+into a game's launch options:
+
+```shell
+ffbwrap --logger=/home/$USER/game.log /dev/input/by-id/usb-Thrustmaster_Thrustmaster_T300RS_Racing_wheel-event-joystick -- %command%
+```
+
+This will create a file called `game.log` (with additional timestamp) in your
+home directory. Preferably change the name to suit the game, but you do you.
+
+> **NOTE:** Most fixes presented in the documentation are more or less obsolete
+> by now, but the tool is still very useful for logging purposes.
+
+## How to capture what USB packets the driver sends to the device?
+
+I'd recommend
+[wireshark](https://www.wireshark.org/)
+
+Usb capture setup is fairly straightforward:
+[wireshark/CaptureSetup](https://wiki.wireshark.org/CaptureSetup/USB#linux)
+
+Here's what I typically do when starting a capture:
+
++ Run `sudo modprobe usbmon`. This will load a kernel module that allows
+  Wireshark to read the USB packets.
+
++ Open wireshark with root privileges. There are some ways to allow wireshark to
+  access the packets with regular user privileges, I just haven't bothered with
+  it.
+
++ Select `usbmon0` from the view that opens up by default.
+
++ The screen will quickly fill up with noise from other devices connected to the
+  computer, so you will have to filter out the noise.
+
++ Run `lsusb` in a terminal. Look for the T300 in the list, you should see
+  something like `Bus 001 Device 006: ID 044f:b66e ThrustMaster, Inc.
+  Thrustmaster T300RS Racing wheel`
+
++ From the previous command, the Bus and Device fields can be used to filter
+  out only packets from/to the device. To see all packets coming from the
+  wheel, add in a filter `usb.src ~ "1\.6\..*"`, where `1` is in this case
+  from the `Bus` field and `6` from the `Device` field. To see all packets
+  being sent to the device, use `usb.dst`.
+
++ This data is probably also filled with a lot of cruft. Data to/from
+  endpoint 2 is button state info, which is probably unnecessary. To see FFB
+  data being sent to the device, use endpoint 1, i.e. `usb.dst == "1.6.1"`.
+  `~` is a Perl-compliant regex operator, whereas `==` just matches the string
+  directly. To see both data coming from the device and going to it, use
+  `usb.dst == "..." || usb.src == "..."`.
+
++ There is also endpoint 0, `usb.src == "1.6.0"` but it doesn't seem to be
+  used for much.
+
++ Use the three buttons in the top left of the screen to start, stop and restart
+  captures.
+
++ Do whatever you want with the device, packets should automatically be
+  captured. When you want to save your capture to a file, stop the recording and
+  go to `File > Export Specified Packets` and make sure `Displayed` is selected.
+  This will apply the filter you've been using, and will only include the packets
+  that are visible in Wireshark, i.e. it applies the filter you've specified.
+
+> **NOTE:** Every time you unplug and replug your wheel, its `Device` field will
+> probably change.
+
+## How to add in support for a new T-series wheel?
+
+Should probably not be too often that you need this info, but essentially use
+wireshark like in the previous example, but spin up a Windows virtual machine
+and install the Thrustmaster drivers on to it, and pass the device to the
+virtual machine. I prefer to use `qemu` with `virt-manager` as a frontend.
+
+With the wheel working under Windows, install
+[fedit.exe](https://gimx.fr/download/b882e209a0ac023d03abbf560dfc3f25fe6367ca/fedit.zip)
+and methodically go through all effects the device supports and compare the USB
+packets the driver sends out. You should be able to build up a table of what
+each value in the USB packet means, see [FFBEFFECTS.md](./FFBEFFECTS.md)
+for an example of what I found out about the T300.