damastas:
I have a Z4 with DSP that the OEM radio stopped working. I was able to put an aftermarket radio in the front, but in order for the DSP to activate and play music over speakers the broken radio still needs to be wired into the IBUS system in the trunk. I want to replace the OEM radio back there with a small board to emulate the OEM radio so that it activates the DSP and my aftermarket radio can use it without the OEM one sitting in the trunk.
I am surprised that the Z4 is still using Ibus. However, my circuit and software is going to be right up your street. I am happy to share it with you if you are interested? I have written the software to use on my K1200LT so will need a tweak as the car steering wheel controls have different Ibus addresses.
I use an Alpine CDE-193BT now and it is controlled by Infra red. It all works perfectly and I have also been able to write to the display.
Next stage is to play with a Microchip MC4017 Digipot to see if I can give compatibility to other head units that use resistive control input.
Some details are on my Farcebook pages: AJL Electronics | Gloucester