i built my own board for a gps-tracking device, using the SAMD G18A from the Zero board.
basically everything is working fine, except stability.
i have multiple boards running, BUT from time to time a board hangs up.
It just hangs up and does not do anything - then i restart the controller, and it is working fine!
it is hard to reproduce the problem. Even when i stress the board, it is working stable, and then out of nothing a few days later it stopps working. Not on all boards, and sometimes stable for weeks.
i implemented a little testing backdoor, i toggle a hardware-pin on a button interupt, so i can check, if the code got stuck in an infinite loop.
When the board hangs up, the pin does not toggle anymore! So, that is a little indicator, but for what?
I know, it will be hard for you to give me hints, but i do not know where/how to find that issue.
I tried to connect everyting similar to the zero schematic to avoid hardware issues like reset-component values, crystal, and so on.
SAMD fuses are stock (eg. BOD off)
i already monitored the free memory, that was an issue at the beginning, and so i implemented an auto-softreset on low memory. That is working fine, but does not solve the problem mentioned above. There must be something else.
It is a pretty huge project, i use an ESP8266 for wifi (Serial2), GSM + GPS with a Sim868 with AT-commands (Serial1), an OLED-Display via I2C, a button, a vibra, Led, and so on ...
The controller is sleeping most of the time and woke up via interrupts (like RTC).
Maybe some power-issue? I use a lipo-cell and various capacitors.
i would expect a reset from the controller, if there is a power retracement?? Or might this cause a HANG?
I would be thankful for every hint or idea! thanks!