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Old 06-18-2013, 08:42 AM   #47
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Join Date: Oct 2011
Location: Melbourne
Posts: 541
My Ride: 330i
Originally Posted by bgennette View Post
Hi again ppmz,

I'm very interested in this project and will probably start building a version of the interface board this weekend. But first I need to check a few things (and I'm sure other watchers will need to know these too).
Good to hear, will be curious to see how you go. Sure you don't want a blank PCB? I think Auspost will do it with a 60c stamp. Or are you planning to improve it?

Originally Posted by bgennette View Post
I worked out that you took pin 16 from the ATtiny to pin 5 (on/off) on the LM25765 voltage regulator module (orange jumper wire in picture from your www.classiccomputing.info web site). I'll be using a dual power module (5V @ 2A & 3.3V @ 0.5A) which will constitute a 3rd board in my setup.
Yep that's right re pin 16. Why do you need 3.3V? I used the LP2950-3.0 for good reason, so standby power loss is very low. If you plan to use the dual module to power the ATtiny, you might find it wastes a fair bit of juice when your car is switched off.

Originally Posted by bgennette View Post
...so to get video with stereo sound the CD Changer inputs need to be commandeered. This also requires running the CD and the Aux Video at the same time, but the infotainment program in the Instrument Cluster is able to be told to do just that.
Not 100% right, it actually uses the RV camera Video input (pin 13), not aux. Aux video-in is a different pin isn't it?

Originally Posted by bgennette View Post
Please, please correct any misconceptions or errors I have made in this summary.

thanx again for a great project .
Looks right to me. The board/schematic/software has a few errors and omissions:

1) D7 shouldn't be there, it ruins the regulation.

2) F1 is meant to be a poly-fuse, but I didn't have one and just linked it.

3) Some of the transistors look like BJTs on the schematic, but MUST be FETs: T4, T5, T6, T7, T8.

4) When I was first wiring/soldering it I had trouble getting the video trigger to work (pin 17) and changed the FET to a BJT (and added a base resistor). Later I found I had a loose wire, so this change may or may not be necessary (probably isn't).

5) The ATtiny firmware has 'power off' disabled because I was still tweaking it. There is one line in the source-code you can comment back in.

6) Make sure you get a ATtiny2313A and not a ATtiny2313.

7) I bought nearly every part from futurlec.com. The relays are: "JRC-23F-03 SPDT 3V 1A PCB Relay".

8) The crystal is a 4.9152 MHz.

9) Most important thing of all - don't forget to adjust your powersupply to 5.0V before plugging it into the Pi.

Last edited by PeteAU; 06-18-2013 at 08:43 AM.
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