In this technical document you will find more detailed info on the CD-i controller port. Philips used an intelligent serial controller interface for the CD-i players, you can connect many useful things like a Keyboard, a mouse, a light gun, a trackerball, a joystick, a remote controller, a modem and you can even connect a CD-i player to a PC with a Null-Modem cable using the CD-i Link & CD-i Stub software developped by CD-i Fan. You can use the controller port as a serial RS232 interface to connect to a modem, with a crosslink cable to a pc or you can use it to connect a pointing device. If you connect a pointing device to the controller port, the Microcontroller installed on it will send a signal to identify himself with a code to the CD-i, this way the player knows what kind of device is connected into the controller port.This identify code is programmed in the microcontroller.
As an exemple, the CDI RV 8701 controller (22ER9019) is based upon the 8 bit PCA84C122 Microcontroller from Philips. The PCA84C122 is not available anymore. So if you want to design a controller interface for the CD-i you must look for alternatives. Paul Hackmann found an alternative and designed a controller interface to use PC Joysticks on a CD-i player. He used a PIC-Controller instead of the PCA84C122. A PIC controller is a programmable Microcontroller chip who is simple to program with a PC and a PIC programmer.
Paul Hackmann developed a tool in the past to get PC controllers to work on CD-i."The CD-i Gamepad Adapter is a cable designed to connect an analog PC joystick or
gamepad to a CD-Interactive (CD-i) player. The cable handles the necessary calibration
of the PC joystick or gamepad, and converts the data from the joystick or gamepad to a
format understood by the CD-i player. With the CD-i Gamepad Adapter, you can enjoy
CD-i gaming with the controller of your choice."
With the converter, you will have a cable like this:
Finally, the controller scheme of the converter:
[Thanks, Paul Hackmann, Terratron]