Hello,
I was hoping to hear your opinion about a serious problem I have - it is either I solve it or reduce my LPC2478 CPU speed from 72[MHz] to 64[MHz] (11% loss. The problem does not seem to be occurring at lower MHz settings). I posted about this in the past but it was a long time ago. When I place a controller in an environmental chamber and increase the temperature to 80+ Celsius degrees, I often see data abort exceptions, and sometimes I get the impression that the PC takes a hike (even the firmware LED that blinks every 1 second becomes irregular for a while before it stops). The program is launched by a boot loader and has a lower level supporting firmware layer that handles some interrupts (not all). I also see that if RTX is not started at all (but the application hangs in a "for (;;)" loop instead, hence the bootloader and firmware layer were/are involved, but the application is idle) - the system never crashes! I have excluded, as far as I could tell, the roll of external memory or RTX in this situation. However, I still suspect RTX a little (even though my test programs never crashed). My question: did you ever encounter such a situation? Where do I look best? can this be the result of a misbehaving peripheral? NXP have confirmed the LPC2478 is not the reason.
Nevill,
Yes, but not me personally. It seems that until 80 degrees (and perhaps slightly more) everything is fine, but them there is a rapid failure as the temperature increases. can it be that the coating in the print disturbs heat dissipation?
What is the humidity of your test chamber?
humidity: 0%.
can it be that the coating in the print disturbs heat dissipation?<p>
Hm, the whole print is coated (including the components)?
yes.
"humidity: 0%."
Whew, dry heat man. Doesn't sound likely to use.
Are you absolutely sure about that?
well, the control panel of the chamber says: "current value: 0". my girlfriend could use the air inside to feed her hair dryer...do you think I should test another setting (but I think that increased humidity will hurt heat dissipation, not...?) ?
It may say 0, but it's very unlikely that humidity in the test chamber is really 0%.
of course, I realize that.
In that case, a look at the thermal properties of the coating material might be in order. And maybe a test with an uncoated unit, if available.