I'm designing an external computer audio interface (192 kHz, 24 bit, stereo using the Cirrus CS5381 ADC) and, I'd like to connect it using firewire.
I'd thought of using an Oxford Semi OXFW... chip, but they got taken over by some outfit called PLX last year and all I can find is NAS/DAS storage chips (SATA) and PCI(e) bridges...
What I was looking for was the simplest sort of serial to FW bridge.
I suppose a TI TSB41AB1 transceiver and TSB12LV01B link layer controller (plus serdes used the wrong way round?) would do it, but (as an amateur) I'm wondering whether I'll be able to get this going without the IEEE standard since the datasheet for the TSB12LV01B does fairly warn
"This document is not intended to serve as a tutorial on 1394; users are referred to the IEEE 1394-1995 serial bus standard for detailed information regarding the 1394 high-speed serial bus."
I guess I'll end up using the FT2232H USB Hi-Speed UART ... :-(
I was on a team that implemented an infra red imager that talked on IEEE
1394, back before it was apparent that FireWire was going to go down in flames in the marketplace (of course, that was back when Microsoft was still pretending to support it -- I actually went to a FireWire user's conference in Redmond).
We got it working, and working quite well. It met every single dang one of our needs except for "works on a popular consumer-oriented bus".
If you want to go the FireWire route, get a copy of "FireWire System Architecture" by Don Anderson of MindShare. It is a near-perfect book for this -- we got copies for every developer, and each one of us was practically able to prop the book up next to our monitor to figure out what needed to get done.
But:
Why?!?!?
Why go with FireWire when USB* will do what you want, and far easier? FireWire is a peer-peer bus, which really, really, really made a lot of sense for the product I was working on (the other end of the digital link was a board that turned the video into RS-170 analog, with no PC in sight). But the fact that it's peer-peer means that -- with a few exceptions -- every node has to have all the capabilities of any other node, which makes the peripheral design much more complex than a master/slave bus like USB.
You, on the other hand, are talking about something that's well within the capabilities of even fairly slow USB hardware -- and you can hardly walk by a computer these days without tripping over a USB cable, while at the same time it's hard to find a computer equipped with FireWire.
For a lot less effort than equipping a peripheral with FireWire you can get a USB-capable microprocessor and do whatever you want.
I'd recommend that you find a chip that'll handle USB isochronous mode (to get you guaranteed bandwidth for that audio that you don't want to hiccup), and get to it. It'll be a _lot_ easier than messing with FireWire, and when you're done you'll be able to plug it into any new computer on earth.
Several of my colleagues from that period of time would be rolling on the floor, pointing at me and laughing, just for making that statement.
--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
Given that 1394 is becoming an interface that's not on new computers, avoid the agony of designing your product to use it. USB2.0 will get 'er done and work on non-vintage computers. I don't consider the loss of it a good thing, but the fact is it's not there...
Thanks (both of you). I suppose that backs up the difficulty in finding suitable chips.
The why is partly due to what I'd read about FW and USB. And because I'd like to get around to doing my own (DSO) oscilloscope interface (i.e. like the electric guitar interface, but running at 12bit / 500 Msps :-)
Maybe I'll get the book, and then do it with USB anyway...
That's pretty high sample rate for a 12 bit A/D converter - those should cost a few bucks. I just repaired a rather unusual scope that had 12 bit A/D converters - a Nicolet Integra 20. It had 4 channels of differential input. However it's sample rate was 1MS/s and it's bandwidth was rated at
True enough. Looks like around 180 USD. I actually just picked the number out of the air, rather than going for the 12bit 1 GSPS chip from TI -- that one costs around 800 USD 8-) Sensibly I might consider going down to 250 MSPS :-) Even more sensibly, I want to do the audio interface first.
Specially designed for those hard to catch slow events? :-) Or for high accuracy,more likely.
Same guy and same company, there's a USB book. I haven't actually _used_ the USB book, but if it's half as good as the FireWire book it's worth the bucks.
--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
And i think i may join them. USB 3.0 is out now and the connectors are=20 different and a lot of other things. See also eSATA. Must also mention=20 PCI-E(xpress) 3.0. Move over InfiniBand, there are new pigs at the = trough.
I once wrote a FireWire camera driver for QNX, to support stereo cameras. But that was 7 years ago.
FireWire is really a local area network, not a "bus". Linux supports IP over FireWire, and Windows XP did, but but Microsoft took that capability out of Vista.
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