Aux-input for the VW Beta

Using the CD-changer input it is possible to connect MP3-players like the iPod to the VW radio.

Intention

Looking for a way to connect external audio sources to the VW Beta, I found the website of Ed Schlunder's (http://k9spud.com/vwcdpic/). The website is down since some time, but he offered the schematics and software for a circuit using a PIC-microcontroller. Here is a mirror of Ed Schlunder's site: http://www.dashwerks.com/misc.orig/websites/www.k9spud.com/vwcdpic/ (thanks to Simone from Italy for the link). This circuit simulates a CD-changer. This way the radio activates its audio-inputs that are normally used by a stock CD-changer, allowing to feed any stereo-signal with line-level to the radio.

I reduced the circuit of Ed Schlunder (it had an onboard PIC-programmer, that I didn't need) to make it easier to build the circuit on a perf board.

Pictures

On the right you'll see the audio inputs. The pins at the middle of the board have to be connected to the radio.

The pinout differs from the one of k9spud:

1. POSITIVE-B+
2. LAUDIO
3. RAUDIO
4. AGND (this is the audio ground, it is not the same as GND)
5. GND
6. DATA-OUT
7. DATA-IN
8. CLOCK-IN
9. NC (not connected)

Parts list

Software

The file "vwcdpic-3.x-2.7d-pic12f629.hex" was working for me.