Hi - I'd like to attach two pci (well actually mini-pci - but they're pretty much identical) cards to one mini-pci slot. I understand that to do this I need to use a PCI bridge between the two cards. Is that correct? And also - I was looking through opencores.org and stumbled upon this: http://www.opencores.org/projects.cgi/web/pci/home - an open source pci bridge Would this work for my application? Thanks! Edit: oops it says it's a bridge between a wishbone SoC and 32 bit pci - so I'm going to guess that that isn't what I want as I don't even have the slightest idea what a wishbone SoC is. So does anyone know of a chip that would work for this? It will be used to connect a mini-pci ethernet/56k card and a 802.11b card to the same mini-pci slot. another edit: I found that TI offers a number of nice looking chips: http://www.intel.com/design/bridge/ - the one that specifically looks of interest to me is the PCI2250: http://focus.ti.com/docs/prod/folders/print/pci2250.html - 176 pins - that is going to be WAY too much fun to solder. Good lord. Intel makes some as well: http://www.intel.com/design/bridge/ but I'm finding much better prices on the TI chips. So - any thoughts? And does anyone know what exactly the difference is between PCI and mini-PCI? Thanks!
I think what you are suggesting is pretty much impossible to achieve. Those chips are really for use by motherboard designers, not general computer modders - unless you're an expert in sirface - mount chip soldering and pcb design, look somewhere else! Having said that, there is a possible solution. You can use two laptop mini pci cards (PCMCIA) in a single normal PC PCI slot. For a suitable pre - built adapter, try here: Dual PCMCIA to PCI adapter I reckon that this is the closest you will get to using two PCI cards in the same slot. Hope this helps! Just noticed that you needed the card to fit into a 'mini PCI' slot. If this is in a small form factor PC, (eg. ITX format) then mini PCI cards are the same as normal ones, but there is less space for the cards to go into. (The cards are not as 'tall' as normal PCI ones. Whilst my suggestion would fit into the slot, you wouldn't be able to get the lid back on... Any chance of some pics of the computer you want to modify (with the lid off)?
Don't worry about the soldering - I can handle that. Here's a picture of a SBC with a mini-pci slot: http://www.webplayer.0catch.com/html/pictures/motherboard2.htm - mini-pci cards were designed for laptops - most built in wireless cards on laptops are mini pci. Here's the official FAQ about them: http://www.pcisig.com/news_room/faqs#mini_pci - one important bit of info there "The Mini PCI card maintains the essential electricals, protocols, PC signals and software drivers as standard PCI v2.2 expansion cards." Looking through the datasheet for that TI chip I linked to - it actually didn't look like it would be too hard to make (very minimal part count for one - which is nice since I have almost no space to work with) - but the only thing I'm worried about is I hear there are capicitance issues to work with when working with PCI - and that's something I have no experience with.
Sorry, I got the card formats mixed up. Is Mini PCI effectivley the same as PCMCIA? (or is it very different?) If it has the same electrical inputs as normal PCI, you could always get one of those cards I mentioned in the last post, solder its connections to the mini PCI, and then use a laptop's Modem and Wireless LAN cards to get what you want.
It's fairly different from PMCIA as far as I understand. For one thing I don't think it's hotswappable - but I could be mistaken (though I doubt that I am - as there would be no need for that function) In the FAQ I linked to it says it's electrically identical to PCI 2.2. I have seen PCI bridge cards - that allow you to attach multiple PCI cards to one PCI slot - but the problem here is space - I don't have any. That's why I'm fairly confident that everything will have to be custom.
what about something like this, if you can get a PCMCIA connection you can get 4 full length PCI slots with this. http://www.mobl.com/expansion/pci/cb4slot/index.html Or something like the 2 slot may me more suited to you. http://www.mobl.com/expansion/pci/13slot/index.html 13 extra PCI slots lets see, 4 HDD's/Controller, * 13 cards52 = HDDs 52 HDDs * 250 GB = 13000 GB = 13 Tb Thats a lot of movies there. Or you could go for SCSI with 7 or 15 hdds per card
OK so I've figured out most of what I need to know so far. Only one thing that still bothers me: Will a PCI bridge be invisible to the computer? Or will it need special drivers and such for it to work?
A PCI bridge *should* be invisible, however, the devices on the bridge won't - obviously. Bridges themselves are nothing but electrical buffers for the PCI protocol. Due to the signaling rate, and electrical characteristics, too keep noise down, the PCI spec requires 'bridges' which act like little PCI repeaters to buffer the electrical signals across the bus. However, note, that PCI bridges do add some latency. This shouldn't be an issue, but if you are using some really time sensitive device, you will see some additional lag over the additional bridge. This is because of the layers of repeaters that the data needs to go through before reaching the CPU. What previous comments were referring to was the fact that these chips require a circuit board to etched and managed. Not for the skills of the 'backyard' modder. However, since you managed to understand what PCI is in the first place, you are probably well beyond that skill level. Good luck! BTW, ProCad is your friend....
Procad? I'm an eagle man myself... But yeah I understand this isn't a small undertaking. Right now I'm praying that I can figure out a way to keep this board on two layers - because otherwise I'll have to outsource the PCB to some company which I'm sure will charge me like $60 or whatever. Right now I'm just sifting through the PCI 2.2 specs (all 322 pages of it! ) so that I can learn how to design PCBs for PCI (as apparently signal degredation is a huge problem) So will it be a problem to not have ground and vcc planes and just replace them with jumpers? Because otherwise it's impossible to make it with only two layers.
I belive plains are recomeneded as a noise reduciton thing, but i've seen prototyping boards for PCI that only have tracks rather than layers, just add a few more tantilum bead caps (the words i design by!)
Between vcc and gnd I'm assuming? And what's a bead cap? Is that just the standard sort of teardrop tantalum?
