From: Alexandre P. N. <al...@om...> - 2005-09-27 15:27:43
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Holly Gates escreveu: >I think for our applications, the main improvements would be: > >- Switching power supplies so input voltage can go down to ~2.5. The >voltage requirements for the current board make it a bit annoying to >power with certain types of batteries or battery arrangements. For >instance, you can't really run off of a one cell lithium ion, or two >alkalines in series. > > I maybe wrong, but to my understanding, pull-up switching power supplies to work with gumstix's power requirements would take quite a space on the board. You could easily mount one on a expansion board, though. Besides, they must oscilate, which generate Low-freq noise which is in most case harmless, but for some data acquisition applications, that could generate some sorts of interference and clock slavery which isn't good. That's true for step-down switchers too, but i've seem quite interesting, small and shielded self-contained controllers, yet haven't seem pull-up ones. I guess it's easy to build an external pull-up, I don't know which sort of efficiency is atainable with it, though (I guess the best pull-up supplies i've seem stay on the 70% range, i.e. it implies an average 30% increase on power consume). But them again, I'm not an expert. >- Thinner overall (not sure if this is really possible, but maybe if you >put all the components on one side). I'm probably the only one who wants >that though so I doubt if it makes sense for you to do. > > I'm satisfied with current gumstix's dimensions, but anything higher than that would be disgusted :-) >I think putting two connectors on the bottom side would be nice since it >would mechanically stabilize the board and provide for more interfacing >without building a stack of boards. Frankly though I haven't had much >problem with mechanical stability using the 60 pin connector and some >double sided tape under the other side of the board. I would probably >utilize the bus interface if it came off on the same side as the 60 pin. >Having the MMC pins come out on that side would be great too since then >I could mount the MMC connector on my daughterboard to keep thickness down. > > Personally, I'm developing a commercial-grade line of products which operates at the "edge" temperature limits and must remains mechanically stable on a high index of impact and vibration environment, for ages like three years or so, thus using tape or otherwise soft material isn't a option for me. I don't need stacking, so two connectors apart of each other on the same side would be "the must". But for stacking-freak ppl, I guess a gender-opposed connectors mirror on the other side of the board would suffice. But that's just me :-) Alexandre |