I have a custom nRF9160 design with Zephyr based firmware having sporadic modem connection issues (ie. waiting to connect forever). When the modem hasn't connected for a while I have a watchdog reset to reset the entire platform. This fixes it most of the time but every once in a while the modem will still not connect after multiple WDT resets. If I physically remove power and re-apply power it comes up and works normally.
There is some failure mechanism that a WTD reset won't fix but a power cycle does. Has anyone else seen this or have any ideas what it is?
Is there some additional\deeper reset that can be done on the modem hardware?
Are there any registers I could try to set\clear after a WDT reset? (Zephyr library calls appreciated)
It' rare so it's hard to isolate but I have seen it several times in the lab and it's been seen in the field.