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.
I am working with the production revision of the hardware. this one seems more stable, but still fails. if I learn something new, I will post it.
Maybe it is a solder problem.
I doubt it. it occurs on many systems, and the hardware has been verified.
"if I learn something new, I will post it."
Like when something is not related to Keil tools.
Egads.
I understand that you have serious problems in finding something that invokes your intellect. do yourself (and us all, unless you have something meaningful to say) a favor, then: be gone.
If you think that the DRAM is the problem, I would try:
- To do a small app where: write to the whole memory (at the highest bandwidth) and then verify. Make an infinite loop waiting for a fail or exception. - Write down info like time-temp. - Run the app for DRAM and then for IRAM or if you have many boards do it at the same time with 3-4 of them.
Hans-Bernhard,
you are right. I am now trying to determine the upper thermal limits of the entire system. it seems a lot more stable now with the production hardware in use - the previous one did use some components whose thermal limits were below 80 degree. so far, 79.3 degrees seem do no harm!
Try increasing the temperature to see if the problem gets any worse.
Leandro,
Despite "stunned Steve"'s doubt about me, I have already tried this (but thanks for the tip anyway) - all my test programs, including the one you described work well under the above conditions and worse. still searching for the smoking gun/component!
Despite "stunned Steve"'s doubt about me
Should of course read:
Despite "stunned Steve"'s doubts about me
I guess you (unlike me, unfortunately...) have found your smoking gun. _SNIFF_ !
Have you checked for dry joints?
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%.