Hi,
this is my really first post, but i've been following the community for long! 
So, I need help. I've got a friend handicapped one of his arms, and I would like to give him the possibility to play with a Sony PSP with a regular PS2 Controller (the one with a cable and two thumbsticks - he loves it).
This is what I would like to do: PSX controller -> arduino pro mini -> PSP
I do not want to chop up the controller, i want to convert the signal with an arduino that has a female PSX port adapter, then I'd like to solder to the correct pads the signals on the PSP (i already figured out all contact points).
My big issue is this: I already "converted" the signal to trigger all buttons from the PSX controller to the PSP, but i cannot find a way to replicate the thumbstick (joystick) functionality.
I've got no ideas.
Hope that I was sufficiently clear fellas, I could post an image to represent my idea better.
Thanks for your help.