Wii under port accessible??

Is it possible to connect a microcontroller or external device to the port that is under the wii.
I want to make an homebrew application that will drive the external device that I will make.
What are the protocols? What are the pinouts?

Thanks for your anwser in advance.

What port are you talking about?

Ohh... My bad! I thought that it was a serial port like every console nintendo had but as I opened it, it was the coin battery holder.

Anyway I will change my question.
How to communicate with external devices.
Maybe I'll have to resign to use the USB connectors and make an homebrew application that use it.

It really depends what you want to do. The USB functions in libogc basically match libusb, but if you want a low level interface there's also the gamecube memory card slots (known as EXI).

I am making a multi console modding project, which is every major nintendo consoles from the NES to the Wii combined into one "box".
What I want is simply translate wiimote button presses into NES/SNES/N64 simulated controller button press.
So from my perspective, I want to play real NES games with my wiimote/gamecube controller.
I think I will go with Wiimote -> Wii (homebrew program) -> USB (libusb) -> Custom microcontroller -> NES control port -> NES.
The Gamecube memory card option is not good for me because I don't want to remove my memory cards when I play other consoles.

I am not familiar with the protocol of USB. Do you think I can send custom I/Os with the current version of libusb with the Wii?

Sure, you can talk to any USB device as long as you know how it operates. A Teensy USB dev board would probably cost less than $20 and provides 25 I/O signals (or pay a bit more and get 46 I/Os).

These boards seem to fit perfectly my project. I'll command one soon.
I can't find any wiibrew project that use libusb, and the devkit ppc don't contain any libusb in portlibs.

I found on the TeensyUsb site that you can send custom ios from/to usb with rawhid functions.
[www.pjrc.com]
And that's the kind of function that I want to call from the wii program.

Where can I download libusb ported for the wii?

You don't need libusb. libogc contains USB functions that are similar to the ones implemented by libusb: [devkitpro.svn.sourceforge.net]

For examples of how to use them, try the source code from libogc's usbmouse and usbkeyboard files:
[devkitpro.svn.sourceforge.net]
[devkitpro.svn.sourceforge.net]