I'm designing the Bone into a fairly expensive piece of equipment.
The price difference between the two boards isn't that much of an
issue. I would like your thoughts on three things.
1) Is the white going to stay in production?
The full set of design files can be gotten. You can get the boards
manufactured anywhere you like even if CircuitCo stops. I wouldn't
worry about it.
am335x is going to be around for a long time. Don't worry about that,
2) Are there enough leads brought out on the black to do 3 SPI ports?
If you mean 3 chip selects, yes. There's only 2 SPI ports on the
am335x, 3 of the chip selects are in the big headers. If the locations
of the SPI pins conflicts, that's dependent on your application of the
board and peripheral usage.
3) Will code that runs on the white drop into the black? I've had a
custom kernel module written to get the SPI to do what I want. Should
it work on the black without modification? Being the same chip, I
would think so.
If you can port your module to Koen's 3.8 (or newer) kernel, yes, it'll
work fine. Might even work better
The silicon changes do impact some kernel code. The 3.2 PSP kernel
tree shouldn't be relied upon for the black or any board running rev
2.0 silicon. Use Koen's tree till everything gets mainlined.
3) If you were in my shoes, which board would you use? All I need are
the ethernet port, some GPIO pins and 3 SPI ports.
Do you need to run at any extreme temperatures? If so, avoid XAM
parts, they're preproduction and not temperature rated. Get CircuitCo
or your favorite board house to build blacks with rev 1.0 silicon (it's
possible, just ask and pay) which can be had with temperature ratings.
If you want to run mainline Linux, give the am335x a little more time.
It's going to happen real soon now. AM180x would be a decent chip,
though (and has a lot more SPI) if you don't need Cortex-A8 features /
speed and you want to stick with TI parts. If you don't want to stick
with TI parts, there's a whole lot of choice out there.
If cost isn't an issue, why not use a SoM from a vendor? You can get
good stuff that's supported in mainline Linux / u-boot for $100 per
unit and that will stay in production for a long time. The carrier
board would be slightly more complex than a cape, but not by much.