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USB "hard drive" 
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LQFP112 - Up with the play

Joined: Thu May 01, 2008 6:30 pm
Posts: 135
Location: Ann Arbor, MI
I was thinking about the all the memory and programming requirements and such - so instead of having everything in the microcontroller - why not have a boot loader (or an OS - like embedded linux) in the micro controller and use a usb stick or CF to store the code and tables? First it will make the code kinda independent from the architecture and second the tables can be much bigger......

Even data logging can be done without a computer....

Tue Jul 22, 2008 9:31 pm
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Joined: Tue Jan 15, 2008 2:31 pm
Posts: 15204
Location: Home sweet home!
Speed and space.

If RAM was large enough to fit such tables, you could do that I guess, but our flash is 15x our RAM, and the tables need to reside in RAM for real time tuning. Secondly, if they were external then you'd have some significant delays getting the data in. It *could* be possible to implement some hard core intelligent caching of a subsection of the table required in ram and use non critical cpu time to try to keep the current load point centred in the cached subset by discarding one edge and loading into another, but the complexity would surely kill you. The tables are already huge really, and we could double their size and still fit them into ram OK. The chances of us running out of flash are slim to none I think. MS2E with ALLLLLL those features still weighs in at about 80k of flash from the 128 they have, we are only at 23k right now because of the huge tables really. The code is only about half at the moment.

Interesting idea though.

I really wanna use such a USB disk for data logging though, if we can figure out a way to get the data onto it efficiently and usably, it would mean 100% full time full logging. I think that would be just awesome!


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Wed Jul 23, 2008 12:24 am
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