The answer is going to be that while android works fine on that board and the ubuntu build works at room temp but not after a -20 cold soak on THAT board, neither one might work on a different board after a -20 cold soak.
This is my personal experience with cold temperature testing on hardware and I did a whole lot of that back around the early 1990s. The problem is very likely with the 3.3v power. The Ubuntu build might touch a feature or enable a component that the android build doesn't and you might be right on the very hairy edge of having enough 3.3v current available at -20C to make the thing operate with android but not with the ubuntu build until it warms up a little bit. The fact that one works and the other doesn't at -20C might just be a fluke of the tolerance build up of all the components of that board. On another board neither one might work. On yet another board maybe both will work, BUT (and this is very important) neither one of them is guaranteed to work because the components on that board are not rated for -20C. In fact, it might work this week but might stop working at -20C next month. Seriously. You are probably chasing your tail looking for a correctable problem when you are using the hardware outside of its design spec. Yeah, it might work -- sometimes -- under just the right conditions -- maybe. Cold does funny things to semiconductors, particularly voltage regulators. In fact, getting power supplies to start was the number one issue in getting gear to turn on after a cold soak at maximum rated cold temperature. Operating at 20 degrees below minimum rated low temp is no different than trying to operate at 20 degrees above maximum rated high temperature. It might work -- for a while -- maybe -- and the results will not be repeatable from one board to the next. Your best bet if you want reliable service is to get someone to build you a board with components rated for that environment. On Thursday, October 10, 2013 4:50:20 AM UTC-7, Kets wrote: > > Hi George, > > Point noted about industrial grade of the beagle board components. But I > have not understood why Android build works fine. Any pointers towards this? > > Regards, > Ketan > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
