Questions about FireWire and Host Controllers


Hey, all I have on my laptop is a little 4-pin firewire port. I had planned on getting a USB 2.0 interface but it doesn't look like Linux support is all that great. My question is will the 4-pin do the trick?

I have an ASUS G50V laptop with a 4 pin connector and it worked for me. I did purchase a laptop ExpressCard which also worked good. I would be more concerned about the hardware working with ffado than anything.


In terms of firewire functionality your 4-pin plug will do just fine. The difference between the small 4-pin you have and the larger 6-pin is the addition of two additional wires which deliver "bus power" - 12V at 1A or there abouts (I forget the exact figures). For devices consuming less than around 12W it is possible to power the device from the computer, saving the need for an additional power source.

The 6-pin plugs are usually only found on desktop computers, both because the size of the socket is less important on those machines and they have no difficulty getting access to a suitable power source to use when providing bus power. Laptops almost always only come with 4-pin firewire (the manufacturers will tell you it's due to a lack of space). Similarly, CardBus firewire cards usually only have 4-pin sockets, although these do have another excuse: the CardBus standard doesn't provide enough electrical power to supply firewire bus power.

So to summarise: your 4-pin socket will work fine. The only "limit" (if you can call it that) is that you'll have to power your firewire device separately. As a later poster commented, probably the bigger concern is that your device works well with ffado.

Awesome thanks for the replies. I just bought a 4pin to 6pin cable for $5, and I'll use the included power adapter with whatever interface I end up getting (I agree figuring that out is the real challenge). There's some good news though.

Running lspci gives:

08:03.1 FireWire (IEEE 1394): Texas Instruments PCIxx12 OHCI Compliant IEEE 1394 Host Controller

So it looks like I at least have a TI chipset. Now just to find a FW interface that works with FFADO that I can afford...