From: Arlen R. <ar...@gm...> - 2012-01-21 20:23:16
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Here are a few things to consider when evaluating an embedded processor for space application. 1: Radiation causing soft failures.. 2. Heat management, as convection cooling does not work in a vacuum. 3. Potential issues with insufficient physical separation between conductors on the PCB when used in a vacuum, which can cause leakage from one trace to another which would not happen in typical ground based applications. (Air is a much better insulator than a vacuum) You can test 2&3 in a vacuum chamber, 1 is a bit tougher to test, and can be worked around in some applications by the use of an external watchdog timer to reset the system. Note that you would want to actually remove power from the COM, then re-apply it after a delay since the Overo processor may be in a latched up state that the typical reset may not clear. I say that the watchdog timer works in some applications, if the processor controls critical functions, having it unavailable while rebooting will likely be unacceptable. For instace, you could have a watchdog timer set for ten seconds, the processor goes out to lunch after one second, nine seconds later a reset occurs with normal operation resuming after 30 seconds. The issue is that totally incorrect system outputs may exist for up to 39 seconds, which could be detrimental to the mission. One space vehicle went out to lunch,. Eventually, communications with mission control were restored, but when the control team checked the systems onboard, they discovered that almost the entire supply of fuel for a reaction motor was expended. The cause was attributed to the processor being unavailable during a reaction motor burn. I.E. the burn started, then continued well past the intended burn duration which wasted almost all of the available fuel. Anyway, good luck to you on a fun project! -Arlen On Fri, Jan 20, 2012 at 1:23 PM, UPCSAT2 <hug...@gm...> wrote: > Thanks > > 2012/1/20 dtran11 [via Gumstix] <[hidden email]> >> >> If you look at the link I provided >> (http://www.sakoman.com/OMAP/an-overiew-of-omap3-power-management-with-2639-pm.html ) >> you will see several tables of power measurements. Here is a snip from the >> page: >> >> Clock (Mhz) Current (mA) Power (mW) >> 720 142 710 >> 600 131 655 >> 550 126 630 >> 500 120 600 >> 250 99 495 >> 125 86 430 >> >> ________________________________ >> If you reply to this email, your message will be added to the discussion >> below: >> >> http://gumstix.8.n6.nabble.com/CUBESAT-LINUX-OVERO-COMPUTER-tp3881829p3883780.html >> To start a new topic under Gumstix, email [hidden email] >> To unsubscribe from Gumstix, click here. >> NAML > > > > ________________________________ > View this message in context: Re: CUBESAT& LINUX OVERO COMPUTER > Sent from the Gumstix mailing list archive at Nabble.com. > > ------------------------------------------------------------------------------ > Keep Your Developer Skills Current with LearnDevNow! > The most comprehensive online learning library for Microsoft developers > is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, > Metro Style Apps, more. Free future releases when you subscribe now! > http://p.sf.net/sfu/learndevnow-d2d > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > |