beagleBone clone, scaling down features to decrease cost

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I'm developing a line of scientific instrumentation that I want to be
21st century compatible (option for dongle ethernet, wifi, bluetooth,
sd card, USB thumbstick)... but its hard to just throw linux at these
devices because I'm concerned about precise timing for sensor control
lines, as well as having around 30Mhz SPI functionality (fast ADC).

Would an 500-700Mhz running Angstrom be able to function as a
real-time OS (or even predictably real, if under-utilized i.e.
processor has lots of idle time)? I'll probably run a web server to
take simple AJAX commands and then stream data out 0.6-1.0 MB/s

What options do I have for scaling down cost (I don't need graphics
acceleration, for instance, and I don't need lots of RAM)

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Hi Nathan,
I can't answer your question directly since I really don't have any real experience with near real-time Linux on the Beagleboard. You might be OK, but I am guessing that you would be pushing if you need precise timing for sensors and especially high speed SPI. What I have done in the past is to use a second smaller processor such as TI MSP/ARM family and ST's ARM offering to offload the real time grunt work and let Linux do what it does best, handling all of the associated peripherals that are supported, servers and so on. Granted that you end up with two development projects, but it may be actually less expensive in the long run if you don't have to tinker with performance issues.

Just my 2 cents.

Mark

P.S. Please start a new thread the next time you post.

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Thanks Mark, I'm actually developing now with a C2000 Picollo
controlStick, and have a Stellaris EKS-LM4F232 dev kit too.

I had considered your option of offloading, but how would I pipe my ~1
Megabyte/second of data over from one chip to linux?

That leads to then, what is the cheapest and smallest linux solution?

www.youtube.com/watch?v=ut9LfQmaYkU

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Actually the Beaglebone is pretty attractive for a low cost Linux solution. Just went and looked closer at the AM3359 processor and the PRU's would make a nice communications interface as well as perhaps offloading some of the your sensor data handling functions.