On our Q2687 boards we’ve noticed they appear to periodically reset and then do not respond to any commands handled by the application (i.e. only responds to built-in commands). I’ve yet to take a log, however a CFUN=1 does manage to reset the processor so it can behave as normal.
What could cause the module to reset like that? Heat? Brownout? Memory leak? I’m sending/receiving UDP with the WIP.
It appears to happen more frequently in hotter conditions. Is there a thermal shutdown of some sort?
It seems (to be confirmed by Sierra Wireless) that AT+WTMR is only working on 3G modules.
We also have same problem with resets and trying to figure it out. When module resets, there is not traces in EEPROM. Startup condition is POWER_ON, not a reboot from exception.
Thinking it may be caused by the heat, we pulled board out of the case (FXT003) and heated it up with heat gun while running AT+WTMR command. Even when chip is very hot to touch, no temperature shutdown was observed.
We also tried to run off bench-top power supply to make sure we do not have brownouts. Same problem.
We are observing problem on Q2686G, FSU004, FXT001.
If you find a cause for the reset, I will be very interested to know.