Hey, I'm looking at making a carputer which is going to start out as an mp3 box, but will eventually expand to movies, n64 emu (only in the back seat of course ), gps, and some other stuff if i hv time. The basic setup is going to be an LCD touchscreen connected to a stowed PC. THe audio output of the PC is gonna be connected to the head unit, a Sony.

My problem is this: Sony requires a proprietary interface to activate the RCA jacks on the back, which is called Unilink. I've found a great site which has reverse-engineered the Unilink protocol and even made a PIC-based hardware interface solution, which is so phat it's unbelievable. It's called Gnunilink, and the link is http://gnunilink.sourceforge.net/ . Now the cool part is that this exists, the bad part is that there's a bunch of gaps in the implementation. Does anyone have any expereince making/designing one of these?? If so, here's a few questions for ya:

Name
Part
QTY

PIC processor
PIC16F627-20
1

10k Resistor
2

47k Resistor
1

BJT
1

Xtal ? MHz
1

100 nF Cap
6

12 pF Cap
2

10 uF Cap
1

TL 7805
1

MAX 202
1

PIC mounting carriage
1

On schematic:

What does SK1/x mean?
Is x the pin number of the rs232 connector?
What does the prefix SK1 mean?

On components:

Will any type of PIC16F627 work? Or does it have to be the one above?
Which type of the above component did you use? There’s a number of PIC16F627-20 types.
What type of BJT is used?
What type of Xtal is used? (speed?)
What does the TL do?
What does the MAX 202 do? Is it an rs232 converter?
Did I leave any parts out or mess up any quantities?
What are the part numbers for the above components?

What a list!

Yes, this project is somewhat lacking in the documentation area. I do not have any actual experience with this project but I might be able to answer most of your questions.

The MAX202 is a RS232 transceiver. However if you look at the photos the device is a MAX3232.

The crystal appears to be 10MHZ from the photographs.

I can not tell what type of transistor the project is using. It probably isn't critical. The PIC documentation might help.

The TL7805 is a 5 VDC voltage regulator IC.

The X in SK1/X appears to be the pin number on the UNILINK connecter. However this does not appear to be consistant in the schematic.

The PIC is a PDIP - Plastic Dual Inline Package. You would want the automotive or industrial temp if possible. Its mounting carriage is called an IC socket. (i.e. in the states ) It probably does not have to be the exact device.

Wow, thanks a lot michaelk! I've been trying to connect the dots for a few weeks now, this gives a me huge jump in the right direction.

Appreciate it!

does anyone know where i can get a hold of the max202 or tl7805 chips? searching on digikey and mouser turned up nothing. also, im thinking about using my laptop since it has mandrake 10 working (finally). anyone have ideas on how to hook the laptop up to the car's power? it's quite a complicated mess, since the laptop has all this power management stuff etc etc