Contents:

Unilink AUX Enabler

Teardown

Parts inside

Teardown

Reverse engineering

Related: Sony Unilink and Inside Unilink on Mictronics | Michaels Electronic Projects, GNUnilink, Sony Unilink pinout.

Unilink AUX Enabler

Sony Unilink is a proprietary protocol used by several Sony car audio devices. Some of them have AUX input available (Sony calls it AUX Lite), some of them have AUX input, but it is available only for devices that identify itself as a Sony peripheral. For this identification and for purpose of control Sony uses Unilink bus.

To make impossible use of third party peripherals, Sony disabled AUX input in the device menu. So if you want to connect third party player (in my case Sharp Zaurus SL-C3200), you need to identify it on the Unilink bus. Hopefully smart people reverse engineered this protocol and made small bazmeg Sony Unilink Headunit AUX Enabler that performs this task.

Also the headunit I got with my car (Sony XR-CA440) uses Unilink to enable AUX. That is why I ordered this enabler.

Teardown

device in partsMy one came somehow defective (weak contact, cold joint or so), so I decided to look inside.

Opening he PCB case: Use violence in the seam to break the glue.

Opening the connector: The top cover has two click latches. Lift the plastic a bit, and you can remove the top cover. Then lift second and third part of the cover. I did not try to open the inner metal case of the connector.

Well, after complete defacing it, it magically started to work, without any fixes. I suspect that the failure was caused by a poor manufacturing of pins of the connector or of the headunit. Contact cleaner spray may help as well. My adapter still fails sometimes, but moving the connector backward and forward always helps to fix it.

Parts inside

Manufacturer tried to hide the hardware inside. But they were not sufficiently thorough. You can see Atmel logo over the scratches, and the first three letters ATM of part number. You can also see several soldering holes that apparently present the standard AVR ISP programming interface. It's sufficient to identify the part as one of ATMEGA processors.

The rest of the enabler consists of 5V power supply and few not so interesting parts.

Teardown

top view bottom view
upper view lower view

Reverse engineering

The device looks pretty well hackable. Here is a schematic created by reverse engineering of the PCB. Note that there may be mistakes and part numbers may differ. You can also download schematic source in the gEDA gschem format. You need to download ATmega8 symbol and set gafrc properly.

Unilink AUX Enabler schematic