http://www.got2getalife.com/DesktopCP/usbhack.html

http://forum.arcadecontrols.com/index.php?topic=64050.0

http://bubbasarcade.tripod.com/home/id1.html

That's the kind of stuff one can find in google.
I'll also send you some pictures of the inside of my foot controller, that might help.

As i said in another thread i recommend buying a relatively good gamepad, especially if one wants to use pots (as in an expression pedal for instance). What happens with cheap gamepads is that the data [hid] gets is not linear any more (it grows from 0 to say 90 as it should, then it gets stuck around 125 for a while, jumps to 150 and grows normally up to 255). This implies that your expression pedal will behave in a strange way. I thus strongly recommend testing the gamepad first with [hid] before hacking.

Pierre

2010/5/7 Aykut Caglayan <aykut_caglayan@yahoo.com>
Hey Pierre,

i write this mail via pd-digest.

I am interested in cheap usb foot controllers; if you can send me some links and whatever, i would be glad

Best
aykut