My observations on the CF28 option board connector

Several of you have been making great strides in figuring out the pinout of the cable(s) that connects the option card to the motherboard. This port shows great promise, like having an internal port replicator connection. Here's what I think we should do to take full advantage of this. We should make a prototyping perfboard about the same size as the option board, with standoffs at the stock screw locations. It should have the mating connector for the ribbon cable to connect to. (unfortunately that is SMD so the project is a little harder to pull off) Each pin of the connector should be brought out to a plated through-hole for attachment.. Maybe each one should go to a row of 4 or 5 through-holes since it is likely that multiple components would connect to some of them. We should take each power pin and ground to convenient locations along the length of the board for easy attachment.

Anyway just daring to dream a little If we had something like this, it would make any project we want to do that much easier. I don't know what it would cost, we surely would be looking at a small quantity of these.. 100-500 boards max i would think? I don't have any PC board design experience so I'm not sure what all it would involve, but maybe this is a good excuse to learn.

 

I dabbled with etching circuit boards a _long_ time ago, with pretty crude methods (hand-drawing with a resist pen). Since this would not be high-density layout by any means (I don't think, I'm not familar with the board in discussion), a good way perhaps to start might be to get a fairly large, fairly high-quality photo or scan of the original board? This way, you can get the original basic size, and locations of mounts pretty perfect.

Then using Photoshop, er, I mean Paint you can draw new traces as needed. On a small-volume run, you need to be able to be able to be (mostly) accurate on cutting out the board, and fairly accurate on drilling holes if you need to put a header strip on.

Doing a quick search, I see there's people that do small runs of PCBs. Disclaimer: I know nothing about these guys, just found it on google. This would do away with the messy/chemical etching part. Some more digging around, and I found that there are standard file formats (Gerber) for PCB. I then found a Perl script to convert PDF to Gerber.

This may all be more complex than this board needs. Some of these guys are talking about multi-layer boards. How many connections on it does it have?

 

It would have a maximum of 50 connections.

 

If you're going to the trouble to make a board like this, why not add a second set of connections for CN40 - another 13 pins in?

 

Looking around quickly, it looks like this guy has a pretty good home-brew process down, using laser printer. He says it's good for traces to 0.01 inches, so that sounds like plenty accurate enough for this.

 

Wow. That's pretty impressive. I might have to start shopping around for a laser printer now...

Just out of curiosity though, what other items could we add on with a board, or would we want to put on?

 

It looks like getting better hah! I think any serial, usb name it wireless lan, etc.

 

Picoshark... That was the method I used when I built my own Porsche diagnostic tool. A guy on the Porsche forum drew out the board and I used my laser printer and ironed it on to the pcb. Then I just put it in a etch bath and it came out perfectly. The only problem would be drilling the holes for the connectors. I have all the drill bits for that. If someone could design the pcb I'd bemore than happy to give it a shot just to see if it works.

 

I'm not familiar with the options board, what all does it have on it? For anything using RF (cell, EVDO, wifi) the connections can only make very short runs without being shielded. It would be too bad to make a board that lost 90% of the power on a wifi connection, for example.

 

Pico.... The pcb we're talking about hosts the stock GPS or the various cellular options that were available. It is screwed to the case/frame just below the battery. Not all have them but all have the stand-offs that they are screwed to.

 

I think that problem could be dealt with by sticking to modules with built-in antenna jacks. I don't think any RF signals would be getting sent back to the motherboard, which is what the proto board I'm envisioning would mainly handle.

 

An add-on that I (and surely others) would find helpful, is a second external USB port. I haven't researched jacks, but would there be room below the battery tray without encroaching into the option board space?

EDIT: looking around quickly, this appears to be one of the smallest female jacks I could find on short notice. I found some that snap in, but this one screws down for mounting. Their volume discount starts at 10 pieces. We wouldn't need the male connector, of course.

 

Hmmmm... That looks like it could be mounted on the cover opposite the LAN & Modem. You'd have a little cutting to do on the inside case though.

You could tie into the USB connections for the port connector in the back.