FPGA beginner

[gonnafail]

The molex connectors are meant to be used with ribbon cable and are not soldered directly to the board. You could solder the ribbon to the board or use two of these molex connectors to make a small patch cable and then use one of the receptacles soldered on your board. The samtec would be nice if it will mount onto standard thickness boards.

[joelby]

I'm puzzled by the Molex plug. How's it supposed to mount to a board? Maybe if you were able to drill and plate rectangular holes...

Yeah.. it's not supposed to be mounted to a board at all

The Samtec is designed for PCB mount, so I was going to just mount it on the edge of my board as their pcb layout recommendation says. I'm getting a sample to see if it'll work on standard 0.063" thick boards. Their document recommends 0.040" thick boards.

Ah! Now I remember. The pins on the top and bottom will probably be flush with the PCB, so if your board is too thick it might not fit on the edge at all. You can usually get away with using a thinner board, but this is usually a bit ugly too and probably not acceptable for this sort of connector (I've done it with SMA end launch connectors and plenty of solder)

[allanw]

Unfortunately it probably won't fit.



I'll try to kludge it anyway. Seems like the easiest and cheapest choice.


Also, these cables aren't too expensive: http://cgi.ebay.com/1FT-ULTRA-VHDCI-SCSI-5-V-MINI-CENTRONICS-68-LVD-CABLE-/380283561946?pt=LH_DefaultDomain_0&hash=item588aaaa7da#ht_1332wt_905

[joelby]

Do you make the boards yourself or get someone to do them? 0.8 mm isn't too much more expensive than 1.6 mm from PCBCART, and the PulsarProFX system comes with 0.8 mm boards.

I've almost convinced myself that I should just get a bunch of connectors from All Best. I'll theoretically need about 5, so this *nearly* works out cheaper than using the Samtec edge mount connector ($33 from element14). Would either of you, or anyone else, be interested in buying some? They'd probably work out to about $15 each + postage. The only annoying thing is that they have a 4-6 week lead time and I'd rather have something a little quicker than that. Given six weeks of thumb twiddling waiting for them (during which I'd miss my project deadline) I could probably get a good way toward designing my own FPGA board with the peripherals I want and wouldn't need any connectors at all.

Using an eBay cable and a through-hole female connector works out to about $65 :-/

[allanw]

I believe you can buy the Samtec connectors directly from their website for $10 each. I ordered one as a sample.

I didn't want to use 0.8mm boards because they're structurally pretty weak, but I guess that doesn't matter too much for something that''ll only be 2" by 2"

[joelby]

Yeah, I'll see if they'll send me some samples as well - hopefully sooner than 4-6 weeks

[joelby]

Good news - the Samtec connectors fit.

The bad news - the data sheet is not so great! Pin alignment isn't described clearly. I thought that the pins were offset by half a pin spacing, but then I looked at the STEP model and they were paired vertically. As I'm in a bit of a rush, I foolishly ordered PCBs yesterday afternoon and the sample connectors arrived today. It looks like they're offset by an entire pin width.

Hopefully it's not too late to get the PCB design changed without incurring the tooling cost again!

Once the boards arrive and I've verified that it's okay, I'd be happy to share the library if anyone wants it. I've also made patterns for the Hirose FX2 and All Best male connectors, though these haven't been verified.

[allanw]

Yeah I got the Samtec sample too. It definitely will not fit on a 63mil thick board. Also, the board must be less than 30mm wide to fit into the connector. Also I may be wrong about the location of the signal pairs. It's probably side-by-side, not on different layers.

[joelby]

Also I may be wrong about the location of the signal pairs. It's probably side-by-side, not on different layers.

I've just checked again with an ohmmeter and they're definitely on different layers.

I also decided that they were offset by half a pin width rather than a full width. I'll be pretty gutted if it doesn't fit my PCB when it arrives!

[fvnktion]

Just FYI, in regard to the VHDCI-CONNECTOR (mates to VHDCI connectors on Digilent boards). 

Now available at digilent store: http://digilentinc.com/Products/Catalog.cfm?NavPath=2,393&Cat=3  search down the list for VHDCI-CONNECTOR.

Also, the datasheet is here:
http://www.digilentinc.com/Data/Documents/Product%20Documentation/R-HS-008068-2C_receptacle.pdf

[mrflibble]

And for those of us in Europe: http://shop.trenz-electronic.de/catalog/product_info.php?manufacturers_id=16&products_id=924

[DavidDLC]

Take a look to the Zedboard.

http://zedboard.org/

It is about the same price and it is newer.

David.